阅读说明：本技术 Iii族氮化物多波长发光二极管 (Group III nitride multi-wavelength light emitting diode ) 是由 I·H·维尔德森 P·P·德布 R·阿米塔奇 于 2018-12-21 设计创作，主要内容包括：一种发光二极管(LED)阵列可以包括基板上的第一像素和第二像素。第一像素和第二像素可以包括一个或多个LED上的一个或多个隧道结。LED阵列可以包括第一像素和第二像素之间的第一沟槽。沟槽可以延伸到基板。(A Light Emitting Diode (LED) array may include a first pixel and a second pixel on a substrate. The first pixel and the second pixel may include one or more tunnel junctions over one or more LEDs. The LED array may include a first trench between the first pixel and the second pixel. The trench may extend to the substrate.)

1. A Light Emitting Diode (LED) array comprising:

a first pixel having a first pair of contacts, a second pixel having a second pair of contacts, and a third pixel having a third pair of contacts;

a first trench separating the first pixel and the second pixel, the first trench extending to a substrate; and

a second trench separating the first pixel and the second pixel, the first trench extending to a substrate.

2. The LED array of claim 1, wherein the first pair of contacts is configured to receive a first voltage independent of the second pixel and the third pixel.

3. The LED array of claim 1, wherein the second pair of contacts is configured to receive a second voltage independent of the first pixel and the third pixel.

4. The LED array of claim 1, wherein the third pair of contacts is configured to receive a third voltage independent of the first and second pixels.

5. The LED array of claim 1, wherein the first pixel is configured to emit light at a first wavelength, the second pixel is configured to emit light at a second wavelength, and the third pixel is configured to emit light at a third wavelength.

6. The LED array of claim 1, wherein the first pixel comprises:

a first LED on the substrate;

a first tunnel junction over the first LED; and

a first semiconductor layer over the tunnel junction.

7. The LED array of claim 1, wherein the second pixel comprises:

a first LED on the substrate;

a first tunnel junction over the first LED;

a second LED on the first tunnel junction;

a second tunnel junction of the second LED; and

a second semiconductor layer over the second tunnel junction.

8. The LED array of claim 1, wherein the third pixel comprises:

a first LED on the substrate;

a first tunnel junction over the first LED;

a second LED on the first tunnel junction;

a second tunnel junction over the second LED; and

a third LED on the second tunnel junction.

9. A system, comprising:

a Light Emitting Diode (LED) array comprising first, second, and third pixels separated by one or more trenches extending to a substrate;

an LED device attachment region having a first pair of electrodes coupled to a first pair of contacts on the first pixel, a second pair of electrodes coupled to a second pair of contacts on the second pixel, and a third pair of electrodes coupled to a third pair of contacts on the third pixel; and

a driver circuit configured to provide independent voltages to one or more of the first, second, and third pairs of electrodes.

10. The system of claim 9, wherein the first pixel comprises:

a first LED on the substrate;

a first tunnel junction over the first LED; and

a first semiconductor layer over the tunnel junction.

11. The system of claim 9, wherein the second pixel comprises:

a first LED on the substrate;

a first tunnel junction over the first LED;

a second LED on the first tunnel junction;

a second tunnel junction of the second LED; and

a second semiconductor layer over the second tunnel junction.

12. The system of claim 9, wherein the third pixel comprises:

a first LED on the substrate;

a first tunnel junction over the first LED;

a second LED on the first tunnel junction;

a second tunnel junction over the second LED; and

a third LED on the second tunnel junction.

13. The system of claim 9, wherein the first pixel is configured to emit light having a first wavelength, the second pixel is configured to emit light having a second wavelength, and the third pixel is configured to emit light having a third wavelength.

14. The system of claim 9, further comprising:

a VLC receiver configured to convert received light into a data signal, the VLC receiver including an amplifying circuit, a filter and an aggregator, a photodiode, and a Clock and Data Recovery (CDR) unit.

15. The system of claim 14, wherein the photodiode comprises one or more of the first pixel, the second pixel, and the third pixel.

16. A method, comprising:

providing a first voltage to a first pixel of a Light Emitting Diode (LED) array;

providing a second voltage to a second pixel of the LED array, the first pixel and the second pixel separated by a first trench extending to a substrate; and

providing a third voltage to a third pixel of the LED array, the second pixel and the third pixel separated by a second trench extending to the substrate.

17. The method of claim 16, wherein the first voltage, the second voltage, and the third voltage are independent of each other.

18. The method of claim 16, wherein the first voltage causes the first pixel to emit light at a first wavelength, the second voltage causes the second pixel to emit light at a second wavelength, and the third voltage causes the third pixel to emit light at a third wavelength.

19. The method of claim 18, wherein one or more of the light of the first wavelength, the light of the second wavelength, and the light of the third wavelength travels through the substrate.

20. The method of claim 16, wherein the LED array is coupled to an LED device attachment region by one or more contacts.

21. An apparatus, comprising:

a first Light Emitting Diode (LED) on a first surface of the substrate;

a first tunnel junction over the first LED;

a first semiconductor layer on the first tunnel junction; and

a conformal dielectric layer on at least sidewalls of the LED and on the first surface of the substrate.

22. The apparatus of claim 21, further comprising:

a first contact on a layer of the first LED; and

a second contact on the first semiconductor layer.

23. The apparatus of claim 21, further comprising:

a second LED on the first tunnel junction, the second LED comprising the first semiconductor layer;

a second tunnel junction over the second LED; and

a second semiconductor layer over the second tunnel junction.

24. The apparatus of claim 23, further comprising:

a third contact on a layer of the second LED; and

a fourth contact on the second semiconductor layer.

25. The apparatus of claim 23, further comprising:

a third LED on the second tunnel junction, the third LED comprising the second semiconductor layer.

26. The apparatus of claim 25, further comprising:

a fifth contact on the first layer of the third LED; and

a sixth contact on the second layer of the third LED.

27. The apparatus of claim 25, further comprising the conformal dielectric layer over the first tunnel junction, the second LED, the second tunnel junction, and the third LED.

28. A Light Emitting Diode (LED) array comprising:

a first pixel and a second pixel on a substrate, the first pixel and the second pixel comprising one or more tunnel junctions over one or more LEDs; and

a first trench between the first pixel and the second pixel, the trench extending to the substrate.

29. The LED array of claim 28, wherein said first pixel comprises:

a first LED on the substrate;

a first tunnel junction over the first LED; and

a first semiconductor layer over the tunnel junction.

30. The LED array of claim 29, further comprising:

a first contact on a layer of the first LED; and

a second contact on the first semiconductor layer.

31. The LED array of claim 28, wherein said second pixel comprises:

a first LED on the substrate;

a first tunnel junction over the first LED;

a second LED on the first tunnel junction;

a second tunnel junction of the second LED; and

a second semiconductor layer over the second tunnel junction.

32. The LED array of claim 31, further comprising:

a second contact on a layer of the second LED; and

a second contact on the second semiconductor layer.

33. The LED array of claim 28, further comprising:

a third pixel on the substrate, the third pixel comprising one or more tunnel junctions formed over one or more LEDs; and

a second trench between the second pixel and the third pixel, the trench extending to the substrate.

34. The LED array of claim 33, wherein said third pixel comprises:

a first LED on the substrate;

a first tunnel junction over the first LED;

a second LED on the first tunnel junction;

a second tunnel junction over the second LED; and

a third LED on the second tunnel junction.

35. The LED array of claim 34, further comprising:

a fifth contact on the first layer of the third LED; and

a sixth contact on the second layer of the third LED.

36. A method, comprising:

forming one or more LEDs and one or more tunnel junctions on a substrate; and

forming a first trench through the one or more tunnel junctions and the one or more LEDs to define a first pixel and a second pixel, the first trench extending to the substrate.

37. The method of claim 36, wherein the first pixel comprises:

a first LED on the substrate;

a first tunnel junction over the first LED; and

a first semiconductor layer over the tunnel junction.

38. The method of claim 36, wherein the second pixel comprises:

a first LED on the substrate;

a first tunnel junction over the first LED;

a second LED on the first tunnel junction;

a second tunnel junction of the second LED; and

a second semiconductor layer over the second tunnel junction.

39. The method of claim 36, further comprising:

forming a second trench through the one or more tunnel junctions and the one or more LEDs to define the second and third pixels, the second trench extending to the substrate.

40. The method of claim 39, wherein the third pixel comprises:

a first LED on the substrate;

a first tunnel junction over the first LED;

a second LED on the first tunnel junction;

a second tunnel junction over the second LED; and

a third LED on the second tunnel junction.

Background

Micro LEDs (uuleds) can be small-sized LEDs (typically 50um in diameter or less) that can be used to create very high resolution color displays when the red, blue and green wavelength uuleds can be arranged in close proximity. The manufacture of a uu display typically involves picking individual uuleds from separate blue, green and red WL wafers and arranging them in alternating close proximity on the display. Due to the small size of each uLED, the pick, arrange, and attach assembly sequence is slow and prone to failure. Worse yet, since increasing resolution generally requires reducing the size of the uuds, the complexity and difficulty of pick and place operations required to fill high resolution uud displays can make them too expensive for widespread use.

Disclosure of Invention

A Light Emitting Diode (LED) array may include a first pixel and a second pixel on a substrate. The first pixel and the second pixel may include one or more tunnel junctions over one or more LEDs. The LED array may include a first trench between the first pixel and the second pixel. The trench may extend to the substrate.

Drawings

A more detailed understanding can be obtained from the following description, given by way of example, in conjunction with the accompanying drawings, in which:

FIG. 1A shows a multiple quantum well Light Emitting Diode (LED);

FIG. 1B illustrates etching the first LED, the second LED, the third LED, the first tunnel junction, and the second tunnel junction to form one or more channels;

FIG. 1C shows different portions of the first LED, the first tunnel junction, the second LED, the second tunnel junction, and the third LED removed;

FIG. 1D shows a third etching step that may further define the pixels;

FIG. 1E illustrates forming a blanket conformal dielectric layer;

FIG. 1F illustrates the formation of an opening in a conformal dielectric layer;

FIG. 1G illustrates forming a contact in an opening;

FIG. 1H shows another contact formed in the opening to form an LED array;

FIG. 1I illustrates the attachment of an LED array to an LED device attachment area;

FIG. 1J shows another example of an LED array;

FIG. 1K shows an LED array forming part of a Visible Light Communication (VLC) system;

fig. 1L shows a VLC receiver;

FIG. 1M is a flow chart illustrating a method of use;

FIG. 1N is a flow chart illustrating a method of forming a device;

fig. 2A is a diagram showing a Light Emitting Diode (LED) device;

fig. 2B is a diagram showing a plurality of LED devices;

FIG. 2C is a diagram showing an LED system with secondary optics;

FIG. 3 is a top view of an electronic board for an integrated LED lighting system according to one embodiment;

FIG. 4A is a top view of an electronic board with an array of LEDs attached to a substrate at an LED device attachment area in one embodiment;

FIG. 4B is a diagram of one embodiment of a two channel integrated LED lighting system with electronic components mounted on both surfaces of a circuit board; and

FIG. 5 is a diagram of an example application system.

Detailed Description

Examples of different light illumination system and/or light emitting diode embodiments will be described more fully below with reference to the accompanying drawings. These examples are not mutually exclusive and features found in one example may be combined with features found in one or more other examples to achieve additional implementations. Thus, it will be understood that the examples shown in the figures are provided for illustrative purposes only, and they are not intended to limit the present disclosure in any way. Like numbers refer to like elements throughout.

It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms may be used to distinguish one element from another. For example, a first element could be termed a second element, and a second element could be termed a first element, without departing from the scope of the present invention. As used herein, the term "and/or" may include any and all combinations of one or more of the associated listed items.

It will be understood that when an element such as a layer, region or substrate is referred to as being "on" or extending "onto" another element, it can be directly on or extend directly onto the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" or extending "directly onto" another element, there may be no intervening elements present. It will also be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element and/or be connected or coupled to the other element via one or more intermediate elements. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present between the element and the other element. It will be understood that these terms are intended to encompass different orientations of the element in addition to any orientation depicted in the figures.

As illustrated in the figures, relative terms such as "lower," "upper," "lower," "horizontal," or "vertical" may be used herein to describe one element, layer or region's relationship to another element, layer or region. It will be understood that these terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures.

Semiconductor light emitting devices or optical power emitting devices, such as devices that emit Ultraviolet (UV) or Infrared (IR) optical power, are among the most efficient light sources currently available. These devices may include light emitting diodes, resonant cavity light emitting diodes, vertical cavity laser diodes, edge emitting lasers, and the like (hereinafter "LEDs"). For example, LEDs may be attractive candidates for many different applications due to their compact size and lower power requirements. For example, they may be used as light sources (e.g., flash and camera flash) for handheld battery-powered devices, such as cameras and cellular telephones. For example, they may also be used for automotive lighting, head-up display (HUD) lighting, horticulture lighting, street lighting, video torch, general lighting (e.g., home, shop, office and studio lighting, theater/stage lighting, and architectural lighting), Augmented Reality (AR) lighting, Virtual Reality (VR) lighting, backlighting as a display, and IR spectroscopy. A single LED may provide light that is brighter than an incandescent light source, and thus, a multi-junction device or LED array (such as a monolithic LED array, a micro LED array, etc.) may be used in applications where more brightness is desired or needed.

The present disclosure relates generally to the fabrication of miniature light emitting diode (uLED) displays and multi-wavelength light emitters with large bandwidths for free-space visible light communications. Epitaxial tunnel junctions may be used to combine multiple emission wavelengths within a single LED device.

Manufacturing a uuled can be simplified if two or more active regions emitting different wavelengths can be integrated within a single wafer. Such an approach may be possible within an AlInGaN material system, as it has been demonstrated that blue, green and red LEDs can all be fabricated in this system. However, the use of multi-color chips in a uLED display requires not only the stacking of multiple layers capable of emitting at different wavelengths within a single epitaxial growth run, but also the ability to vary the respective emission intensity ratios between emitters of different wavelengths.

One possible way to fabricate multi-color uuled chips may be to form Multiple Quantum Wells (MQWs) capable of emitting red, green, and blue light within a single active region (i.e., between the p-layer and the n-layer of a p-n junction). By an optimized growth sequence of multiple quantum wells, the LED has one primary color that can be varied depending on the drive current, e.g., it may appear predominantly red at low currents, predominantly green at intermediate currents, and predominantly blue at high currents. However, this type of color control mechanism makes it difficult to adjust the surface radiation and dominant wavelength of the LED independently of each other, and as a result the color purity may be poor.

Alternatively, two or more pixels of different wavelengths may be formed in the same device footprint by growing several p-n junction LEDs within the same epitaxial wafer. A multi-level mesa etch process may be performed to make independent electrical contacts to each of the p-n junctions. One or more emitter layers of different wavelengths may be embedded in separate p-n junctions with separate current paths, so that wavelength and radiation may be independently controlled. Unfortunately, given current post-epitaxial device processing limitations, it may be difficult to fabricate such multi-wavelength uuds. Dry etching may be typically required to open the vias for contacting the buried layer. The dry etching process introduces atomic damage to the crystal, which changes its conductivity type from p-type to n-type. Due to this conductivity type conversion, it may not be possible to obtain a low-resistance ohmic contact with the buried p-type nitride surface that has been exposed by dry etching. In practice, creating a non-ohmic contact to the etched p-GaN surface may result in a one volt or more forward voltage loss for some active regions. Such large forward voltages may not be considered practical with respect to the power consumption requirements of the microdisplay.

According to other embodiments of the invention, a multi-quantum-well LED suitable for use in a wafer-scale uuled may include a first LED including a set of quantum wells capable of emitting light at a first wavelength. A second LED comprising a set of quantum wells may also be formed, wherein the second LED is capable of emitting light of a second wavelength different from the wavelength emitted by the first LED. A tunnel junction layer may be formed to separate the first and second LEDs. The quantum wells in the LEDs may be caused to emit light injection currents from separate electrical contacts extending to each of the first and second LEDs. In some embodiments, three or more LEDs may be defined to allow RGB uLED.

In another embodiment, a method of fabricating a multiple quantum well LED includes forming a first LED including a set of quantum wells on a substrate. A tunnel junction layer may be formed on the first LED, and a second LED may be formed on the tunnel junction layer. At least one trench having sidewalls may be etched through the first LED to define at least two light emitting regions in the multiple quantum well LED. Metal contacts may be applied to provide separate electrical contacts to each of the first and second sets of quantum wells. The p-GaN layer may be activated at least partially after annealing to promote diffusion of hydrogen through the sidewalls of the etched trench. In some embodiments, trenches having sidewalls may be etched through to the substrate, while in other embodiments, the etching is only to the n-GaN layer located on the substrate.

FIG. 1A illustrates a plurality of LEDs formed on a substrate that can be used to form the LEDs. The LEDs may have multiple quantum wells, multiple defined channels separating the LEDs into different pixels, and/or discrete wavelength emitter sites for Visual Light Communication (VLC). The uuled device may comprise a mesa structure and separate electrical contacts.

In the following description, it will be understood that the terms light emission, color, red/green/blue and RGB may include any light mostly consisting of, centered at or having primarily a specified wavelength. In some embodiments, the light emission may also include non-visible light, including near IR and UV light. In other embodiments, the multiple quantum wells may support closely matched but still different emission wavelengths (e.g., independently modulated dual blue emitters with respective 430nm and 460nm peak wavelengths).

Referring now to fig. 1A, a multiple quantum well LED may include a substrate 106, which substrate 106 may be formed of sapphire, patterned or unpatterned. In some embodiments, the substrate 106 may be polished and used to form at least a portion of a display. The substrate 106 may support a light emitting LED, which may include multiple p-layers and n-layers sandwiching one or more sets of quantum wells, wherein at least some of the quantum wells form an active region capable of light emission. For example, the substrate 106 may support a first set of quantum wells positioned between an n-GaN layer and a p-GaN layer to form a first LED101 capable of emitting light at a first wavelength (e.g., blue). A second set of quantum wells may be located between the n-GaN layer and the p-GaN layer to form a second LED 103 capable of emitting light at a second wavelength (e.g., green) different from the first wavelength, wherein the first tunnel junction 102 separates the first LED101 and the second LED 103. A second tunnel junction layer 104 may be formed on the second LED 103, and a third set of quantum wells may be located between the n-GaN layer and the p-GaN layer to form a third LED105 capable of emitting light of a third wavelength (e.g., red) different from the first and second wavelengths. As described below, individual electrical contacts may be formed as contact pairs to provide sufficient voltage and current to induce light emission from each of the first LED101, the second LED 103, and the third LED105 of a suitable printed circuit board. In some embodiments, each of the first LED101, the second LED 103, and the third LED105 may be independently voltage biased.

Advantageously, the number of epitaxial growth runs required to produce a source die for a uLED display can be reduced to one-third the number or run required by existing methods (or one-half if only two wavelengths are stacked) compared to a uLED display made from a conventional single wavelength uLED, thereby reducing cost and improving throughput at the epi fabrication stage. Furthermore, the number of pick and place operations required to fill the display can be halved or reduced to one third, since two or three pixels can be transferred in each pick and place operation.

For even more efficient manufacturing, in wafer scale embodiments that allow for efficient growth of all required wavelengths on one epi wafer, no pick and place may be required. The display uLED may remain on a continuously polished sapphire support/substrate that may form part of the packaging of the uLED display.

As another advantage, the disclosed structures and methods avoid the problems associated with making ohmic electrical contact to an etched p-GaN surface, enabling lower operating voltages and higher conversion efficiencies (wall-plug efficiencies), because all contacts to the buried layer can be made at the n-GaN surface. The number of etching steps to make all necessary electrical contacts can also be reduced and the limitations on the control of the etch rate can be relaxed, since all etched contacts in the tunnel junction invention can be made to a thick n-GaN layer (relative to a typically thinner p-GaN layer), even while maintaining high LED efficiency.

As seen in fig. 1A, a plurality of LEDs of quantum wells capable of light emission of various wavelengths may be formed on the substrate 106. Substrate 106 may be capable of supporting epitaxial ill-nitride film growth. The substrate 106 may be composed of, for example, sapphire, patterned sapphire, or silicon carbide. The first LED101 may be formed on the substrate 106. The first LED may be composed of any group III-V semiconductor including binary, ternary, and quaternary alloys of gallium, aluminum, indium, and nitrogen, also referred to as III-nitride materials. In an example, the first LED101 may be composed of GaN. The first LED101 may be formed using conventional deposition techniques, such as Metal Organic Chemical Vapor Deposition (MOCVD), Molecular Beam Epitaxy (MBE), or other epitaxial techniques. In an epitaxial deposition process, the chemical reactants provided by one or more source gases may be controlled and system parameters may be set such that the deposition atoms reach the deposition surface with sufficient energy to move around on the surface and direct themselves to the crystal arrangement of atoms of the deposition surface. Thus, the first LED101 may be grown on the substrate 106 using conventional epitaxial techniques.

The first LED101 may be formed of any suitable material to emit photons when excited. More particularly, the first LED101 may be formed from group III-V semiconductors (including, but not limited to, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb), group II-VI semiconductors (including, but not limited to, ZnS, ZnSe, CdSe, CdTe), group IV semiconductors (including, but not limited to, Ge, Si, SiC, and mixtures or alloys thereof).

The first LED101 may include a first semiconductor layer 107, an active region 108 on the first semiconductor layer 107, and a second semiconductor layer 109 on the active region 108. The first semiconductor layer 107 may be an n-type layer and one or more layers of semiconductor material (including, for example, a preparation layer, such as a buffer layer or nucleation layer) including different compositions and dopant concentrations, and/or a layer designed to facilitate removal of the growth substrate. These layers may be n-type or not intentionally doped, or may even be p-type device layers. These layers may be designed for specific optical, material, or electrical properties desired for the light emitting region to efficiently emit light. The active region 108 may be between the first semiconductor layer 107 and the second semiconductor layer 109, and may receive a current such that the active region 108 emits a light beam. The second semiconductor layer 109 may be a p-type layer and may include multiple layers of different composition, thickness, and dopant concentration, including layers that may not be intentionally doped, or n-type layers. A current may be caused to flow through the p-n junction in the active region 108 (e.g., via the contact), and the active region 108 may generate light at a first wavelength determined at least in part by the band gap energy of the material. The first LED101 may include one or more quantum wells.

A first tunnel junction 102 may be formed on the first LED 101. The first tunnel junction 102 may be a barrier layer, such as a thin insulating layer or an electrical potential. The first tunnel junction may be between two conductive materials. Electrons (or quasi-particles) may pass through the first tunnel junction 102 through the process of quantum tunneling. The first tunnel junction 102 may be formed using conventional deposition techniques, such as MOCVD), MBE, or other epitaxial techniques.

A second LED 103 may be formed on the first tunnel junction 102. The second LED 103 may be similar to the first LED101 and may be composed of similar layers. The second LED 103 may be formed using a technique similar to that described above with reference to the first LED 101.

A second tunnel junction 104 may be formed over the second LED 103. The second tunnel junction 104 may be similar to the first tunnel junction and may be composed of similar layers. The second tunnel junction 104 may be formed using techniques similar to those described above with reference to the first tunnel junction 102.

A third LED105 may be formed on the second tunnel junction 104. The third LED105 may be similar to the first LED101 and may be composed of similar layers. The third LED105 may be formed using techniques similar to those described above with reference to the first LED 101.

The first semiconductor layer 107, the active region 108, and the third semiconductor layer 109 of each LED may be composed of different materials such that one or more of the first LED101, the second LED 103, and the third LED105 emit light of different wavelengths. For example, the first LED101, the second LED 103, and the third LED105 may emit different red, green, and blue light. In another example, the first LED101, the second LED 103, and the third LED105 may emit light of different wavelengths (e.g., separated by approximately 10-30 nm) within a particular color range (e.g., 420-480 nm).

Although any order of arranging the different LEDs may be possible, in one embodiment, the LED having the active region that emits the shortest wavelength may be the first to grow in the sequence. This arrangement may avoid or minimize internal absorption of blue emission by longer wavelength active regions.

The epitaxial growth conditions may be similar to those required for conventional blue LED growth operation using patterned or unpatterned sapphire substrates. After the sequential growth of the n-GaN layer, the blue-emitting multiple quantum well, and the p-GaN layer collectively forming the LED101 capable of emitting blue light is completed, the growth conditions may be changed to grow the first tunnel junction 102.

After the first tunnel junction 102 is formed, a second LED 103 capable of emitting green light may be formed. The second LED 103 may also be grown in a similar manner to a conventional green LED. The thickness and/or growth conditions of the n-contact layer may be further modified. After completing the second semiconductor layer 109 of the second LED 103, the second tunnel junction 104 may be grown.

The third LED105 may be a red emitting InGaN LED. The growth of the third LED105 may be similar to the growth of a conventional red LED, but the thickness of the n-contact layer and/or the growth conditions may be further modified.

As will be appreciated, various designs of the first and second tunnel junctions 102, 104 or LED active regions may be used. The first and second tunnel junctions 102, 104 may facilitate lateral current propagation and may include any layers having different group III element compositions and/or different doping concentrations for the first and second semiconductor layers 107, 109. The first tunnel junction 102 and the second tunnel junction 104 may utilize polarized dipoles that naturally occur at the interface between nitride layers of different group III element compositions. The first tunnel junction 102 and the second tunnel junction 104 may be created by forming a low resistance p-type confinement layer in combination with various impurities that can create an intermediate gap state.

Referring now to fig. 1B, a first LED101, a second LED 103, and a third LED105, each having a multiple quantum well, and a first tunnel junction 102 and a second tunnel junction 104 may be etched. The etching may include conventional photolithographic and dry etching processes to define the one or more channels. The first channel 111 may define a first pixel 113 and a second pixel 114. The second channel 112 may define a second pixel 114 and a third pixel 115.

Conventional dry etching processes may be used, but various combinations of masks and etch depths may be required. Conventional photoresist exposure, development, stripping and cleaning steps are understood in the art and have been omitted from the drawings. A layer 116 of conventional photoresist may be formed over the first pixel 113, the second pixel 114, and the third pixel 115.

The first and second channels 111, 112 may be formed by leaving portions of the LED unmasked during etching. It may be desirable for these locations to etch back down to the substrate 106. Due to the very slow etch rate of sapphire relative to the epitaxial layers of the LED, the first etch process can effectively stop on sapphire.

The surface of the first semiconductor layer 107 in the first LED101 may be left during the etching process to serve as the n-contact 110 of the first pixel.

Referring now to fig. 1C, different portions of the first LED101, the first tunnel junction 102, the second LED 103, the second tunnel junction 104, and the third LED105 may be removed in a second etching process to further define different pixels.

Each of the first and second channels 111 and 112 may extend to expose the substrate 106. The first pixel 113 may be etched to expose the upper surface 117 of the first semiconductor layer 107 in the second LED 103. The surface 117 may serve as a p-type contact for the first pixel 113. The second pixel 114 may also be etched to expose the upper surface 117 of the first semiconductor layer 107 in the second LED 103. The surface 118 may serve as an n-type contact for the second pixel 114.

Referring now to fig. 1D, a third etching step may be performed to further define the pixels. The second pixel 114 may be etched to expose an upper surface 119 of the first semiconductor layer 107 in the third LED 105. The surface 119 may serve as a p-type contact for the second pixel 114.

The third pixel 115 may be etched to expose the upper surface 120 of the first semiconductor layer 107 in the third LED 105. The surface 120 may serve as an n-type contact for the third pixel 115. The unetched second semiconductor layer 109 in the third LED105 may serve as an n-contact 120 of the third pixel 115. In practice, etching of the p-contacts of the first pixel 113 and the second pixel 114 may remove the light absorbing layers of these pixels (e.g., green and red LEDs may absorb light emitted from blue LEDs).

It should be noted that the first pixel 113, the second pixel 114, and the third pixel 115 may be formed in any combination and in any configuration. For example, more than one of the first pixel 113, the second pixel 114, and the third pixel 115 may be adjacent to each other. Further, the first pixel 113, the second pixel 114, and the third pixel 115 may be arranged such that the first pixel 113 is adjacent to the third pixel 115. Further, a device including one type of pixels, two types of pixels, or all three types of pixels may be formed. Furthermore, the number of LEDs and tunnel junctions described above is not meant to be limiting.

In an example, p-GaN activation can be accomplished by facilitating lateral diffusion of hydrogen through the sidewalls of the etched trench, after photoresist stripping and cleaning (i.e., after completing the third dry etch shown in fig. 1D), an anneal can be performed. Annealing at this point rather than earlier in the process may be advantageous because the defined channel between pixels may provide an efficient path for lateral diffusion and escape of hydrogen from the p-GaN layer. Activation annealing process conditions that promote hydrogen diffusion may be similar to or different from those of conventional LEDs, and no special annealing conditions are required herein. Alternatively, an epitaxial process with minimal hydrogen (e.g., MBE or RPCVD) may be used to grow the tunnel junction, and an anneal to remove the hydrogen by lateral diffusion would not be required.

After the p-GaN activation anneal, various additional processing steps may be required to define the electrical connections to the pixels.

As seen in fig. 1E, a conformal dielectric layer 122 may be formed over the first pixel 113, the second pixel 114, and the third pixel 115. The conformal dielectric layer 122 may be formed using a conventional deposition process, such as plasma enhanced chemical vapor deposition. The conformal dielectric layer 122 may be comprised of a dielectric material such as silicon dioxide. A conformal dielectric layer 122 may be formed. The electrically insulating conformal dielectric layer 122 may passivate the mesa sidewalls and isolate metal contact pads deposited in subsequent process steps from each other.

Referring now to fig. 1F, an opening may be formed in the conformal dielectric layer 122. As illustrated above with reference to fig. 1D, portions of the conformal dielectric layer 122 may be masked with resist 116, and portions may remain exposed. The exposed portions may be removed using a conventional etching process such as a dry action. The first opening 123 may be formed on the first pixel 113 to expose the first semiconductor layer 107 of the first LED 101. A second opening 124 may be formed on the first pixel 113 to expose the first semiconductor layer 107 of the second LED 103. A third opening 125 may be formed on the second pixel 114 to expose the first semiconductor layer 107 of the second LED 103. A fourth opening 126 may be formed on the second pixel 114 to expose the first semiconductor layer 107 of the third LED 105. A fifth opening 127 may be formed on the third pixel 115 to expose the first semiconductor layer 107 of the third LED 105. A sixth opening 128 may be formed on the third pixel 115 to expose the second semiconductor layer 109 of the third LED 105.

Referring now to fig. 1G, a metal (e.g., an aluminum/gold bilayer) may be evaporated for metallization and patterned by lift-off to form one or more of the first contact 129a, the second contact 129b, the third contact 129c, the fourth contact 129c, and the fifth contact 129 d. As shown in fig. 1G, the lift-off mask opening may coincide with an opening in the dielectric. The first contact 129a may be formed in the first opening 123 and may be on the first semiconductor layer 107 of the first LED 101. The first contact 129a may be an n-type contact for the first pixel 113. The second contact portion 129b may be formed in the second opening 124 and may be on the first semiconductor layer 107 of the second LED 103 in the first pixel 113. The second contact 129b may be a p-type contact for the first pixel 113.

The third contact 129c may be formed in the third opening 125 and may be on the first semiconductor layer 107 of the second LED 103 in the second pixel 114. The third contact 129c may be an n-type contact for the second pixel 114. The fourth contact 129d may be formed in the fourth opening 126 and may be on the first semiconductor layer 107 of the third LED105 in the second pixel 114. The fourth contact 129d may be a p-type contact for the second pixel 114.

A fifth contact 129d may be formed in the fifth opening 127 and may be on the first semiconductor layer 107 of the third LED105 in the third pixel 115. The fifth contact 129d may be an n-type contact for the third pixel 115.

As shown in fig. 1H, a sixth contact 130 may be formed in the sixth opening 128 on the third pixel 115 using a metallization process. The sixth contact 130 may be composed of silver and may be similarly evaporated and patterned onto the second semiconductor layer 109 of the third LED105 to form the LED array 121 as shown in fig. 1H.

As seen with respect to fig. 1I, after singulation of the wafer, the LED array 121 may be attached to an LED device attachment region 318, as described in further detail below. In an example, the LED device attachment region 318 may be a Complementary Metal Oxide Semiconductor (CMOS) Integrated Circuit (IC) array having metal interconnect joints corresponding to contacts formed on the LED array 121. The first surface of the LED device attachment region 318 may have one or more interconnect bumps corresponding to contacts on the pixel. The interconnect bumps may have different heights defined to match the first pixel 113, the second pixel 114, and the third pixel 115, thereby allowing the use of substantially the same size interconnect bonding structures. In other variations, the first surface of the LED device attachment region 318 may be substantially flat and different heights of the insert or connecting post may be used. A driver circuit, as described below in connection with fig. 4B, may be coupled to the LED device attachment region 318 to allow each contact pair of the first pixel 113, the second pixel 114, and the third pixel 115 to be independently biased at a desired voltage. For example, the driver circuit may include a driver configured to provide a first drive current to a first pair of electrodes 152 coupled to the first pair of contacts (129 a and 129 b), a second pair of electrodes 154 coupled to the second pair of contacts (129 c and 129 d), and a third pair of electrodes 156 coupled to the third pair of contacts (129 e and 130).

For example, the LED device attachment region 318 may be configured to provide a voltage to only the first contact 129a and the second contact 129b (collectively referred to as a first pair of contacts) of the first pixel 113, to only the third contact 129c and the fourth contact 129d (collectively referred to as a second pair of contacts) of the second pixel 114, and to only the fifth contact 129e and the sixth contact 130 (collectively referred to as a third pair of contacts) of the third pixel 115. The LED device attachment region 318 can be configured to provide a voltage in any combination described above. The LED device attachment region 318 may be coupled to the LED device attachment region 318 described below with reference to fig. 3.

Light of a first wavelength may be emitted from the first pixel 113 through the substrate 106, light of a second wavelength may be emitted from the second pixel 114 through the substrate 106, and light of a third wavelength may be emitted from the third pixel through the substrate 106.

Referring now to FIG. 1J, another example of an LED array 138 is shown. The LED array 138 may be formed using the same or similar epitaxial growth processes and wafer processing steps as described above, but using different mask settings to etch different layers. The mask used in this embodiment may be modified to prevent etching of the trench down to the substrate 106.

Trenches 136, 137, and 139 may be masked for all etching steps, but may not be masked for the metal deposition steps described above. This may result in the LED array 138 having the first common electrode 132 and the second common electrode 133, the first common electrode 132 may be used for the p-contact of the first pixel 113 and the n-contact of the second pixel 114, and the second common electrode 133 may be used for the p-contact of the second pixel 114 and the n-contact of the third pixel 115. It may be possible to generate electroluminescence from any of the individual active areas or any combination thereof (including all three) by applying an appropriate bias to the drive electrode 132, 133 or 135 relative to the ground electrode 134. For example, the driving voltage may be a combination of 3/6/9V resulting in illumination of the first pixel 113, the second pixel 114, and the third pixel 115 together. The combination of 3/3/6V may result in illumination of the third pixel 115 and the first pixel 113 without passing any current through the second pixel 114.

While the first LED101, the second LED 103, and the third LED105 may emit light simultaneously, the LED array 138 may support higher pixel resolution (i.e., a single uuled may produce all wavelengths previously required to be produced by 3 uuleds), although potentially requiring higher voltages, due to the reduction in the total footprint of the LED array 138. The smaller footprint may be the result of the smaller required electrical contact area and the lack of isolation gaps between pixels of individual wavelengths. The complexity of the printed circuit board may also be reduced.

In order to support the ever-increasing amount of data traffic transmitted using wireless communications, it is necessary to develop a Gbit/sec-like communication system. However, there is currently insufficient available radio spectrum to develop radio frequency wireless systems with speeds in the Gbit/sec range. One alternative to radio frequency wireless is to provide Visible Light Communication (VLC), which uses wavelengths in the visible region of the spectrum. VLC is a data communication variant that uses visible light between 140 and 800 THz (780-375 nm). VLC is a subset of optical wireless communication technologies. VLC may use fluorescent lamps (e.g., ordinary lamps, rather than special communication devices) to transmit signals at 10 kbit/s, or may use LEDs up to 112 Mbit/s over short distances. The system may be capable of transmitting at full ethernet speed (10 Mbit/s) over a distance of 1-2 kilometers (0.6-1.2 miles).

Specially designed electronic devices that typically contain photodiodes may receive signals from a light source, although in some cases a conventional cell phone camera or digital camera may be sufficient. The image sensors used in these devices may be an array of photodiodes (i.e., pixels), and in some applications, the use of an array of LEDs may be preferred over a single photodiode. Such sensors may provide spatial perception of multiple channels (e.g., 1 pixel = 1 channel) or multiple light sources.

VLC can potentially provide unlicensed bandwidth on the order of THz/sec, support a high degree of spatial reuse, and allow for greater security due to the inherent difficulties of interception. In addition, VLC may use existing infrastructure designed for lighting, which may enable additional wireless transmission capacity with relatively small capital investment.

The data transfer rate of white LEDs that may have conventional phosphor conversion may be generally limited to below 100MBps due to, among other factors, the slow time response of the phosphor. On the other hand, a white light source mixing wavelengths emitted from two or more independently modulated LED sources has an increased bandwidth and is capable of data transmission rates up to 5 GBps.

A white light source consisting of three separate blue, green and red LED chips can meet the requirements for both illumination and high bandwidth VLC applications. Alternatively, multiple blue chips with peak Wavelengths (WL) that differ by 20nm or more, each chip having a phosphor to form white light, can be put into a single package to increase the bandwidth of the filters used on each detector to prevent cross-talk between different blue sources. Unfortunately, for both alternatives, the large amount of space required to assemble multiple individual chips prevents the design of compact, highly directional VLC systems.

The devices described above may support VLC applications. The first contact 129a, the second contact 129b, the third contact 129c, the fourth contact 129c, the fifth contact 129d, and the sixth contact 130 may be independently drivable to define light emission from each of the first pixel 113, the second pixel 114, and the third pixel 115 to support the VLC protocol.

Referring now to fig. 1K, a diagram illustrating a combined display and VLC system 140 is illustrated. A smart phone 402 with a display 141, a VLC transmitter 142, and a VLC receiver 143 (shown in a draft not to scale) may be used to interact with other devices, such as a ceiling mounted LED light 144 or another smart phone 145 that supports VLC protocols, such as Li-Fi.

The VLC transmitter 142 may also be capable of functioning as a display, although the display and VLC functions may be separate. The VLC emitter 142 may include the LED array 121 and the LED array 138 described above.

The VLC receiver 143 may comprise an avalanche photodiode or, when more sensitive operation is required, a Single Photon Avalanche Diode (SPAD). The smart phone 402 may include circuitry for converting the data that needs to be transmitted into a suitable drive modulation for the selected VLC transmitter. The smart phone 402 may also include circuitry for converting the light modulation received from the VLC receiver into usable data. The VLC receiver 143 may be the sensor module 314 described below with reference to fig. 3.

Referring now to fig. 1L, a diagram illustrating a VLC receiver 143 is shown. The VLC receiver 143 may include an amplification circuit 149 and a filter and condenser 146. Due to the illumination of a large area, beam divergence in the LED may occur, resulting in attenuation. The condenser 146 may be used to compensate for this type of attenuation. Furthermore, VLC may be susceptible to interference from other sources such as sunlight and other illumination. Accordingly, the filter 146 may be used to mitigate the DC noise component present in the received signal.

In the VLC receiver 143, the light may be detected using the photodiode 147, and may be converted into a photocurrent. The photodiode may include one or more of a silicon photodiode, a PIN diode, and an avalanche photodiode. The photodiode 451 may include one or more of the first pixel 113, the second pixel 114, and the third pixel 115. The photocurrent may be received by a Clock and Data Recovery (CDR) unit 148. The CDR unit 148 may provide an output to one or more circuits in the VLC system 140.

The light may pass through a filter and condenser 146 and be detected by a photodiode 147. Amplification circuit 149 may amplify the signal and provide it to CDR unit 148, which CDR unit 148 may decode and process the signal.

The first pixel 113, the second pixel 114, and the third pixel 115 may be independently electrically connected to allow high speed light intensity modulation and data transfer using IEEE 802.15.7 or other suitable wireless protocols. Since multiple wavelengths can be supported, improved protocols based on Optical Orthogonal Frequency Division Multiplexing (OOFDM) modulation can be used. The VLC signals may be directed to an LED array having stacked active regions that emit light at different wavelengths. Each pixel may emit a different wavelength or, alternatively, each pixel may emit more than one wavelength.

Using a multi-wavelength system such as LED array 121 and LED array 138 can deliver connections with data transfer rates up to about 5Gbps, which is advantageous compared to phosphor coated white LEDs, which can only deliver up to about 100 Mbps.

Color Shift Keying (CSK), outlined in IEEE 802.15.7, is an intensity modulation based modulation scheme for VLC. CSK is intensity based because the modulated signal exhibits an instantaneous color equal to the physical sum of the instantaneous intensities of the three RGB LEDs. The modulated signal jumps instantaneously, from symbol to symbol, across different visible colors. Thus, CSK may be interpreted as a form of frequency shift. However, due to the limited time sensitivity in human vision, such transient changes in the transmitted color may not be perceptible to humans. The critical flicker fusion threshold (CFF) and the critical color fusion threshold (CCF) may limit human resolution to temporal variations shorter than 0.01 seconds. The transmissions from LED array 121 and LED array 138 may be preset to be time averaged (by CFF and CCF) for a particular time constant color. A human may only perceive a preset color that appears to be constant over time, but not an instantaneous color that changes rapidly in time. In other words, CSK transmission can maintain a constant time-averaged luminous flux even when its symbol sequence varies rapidly in chromaticity.

Referring now to FIG. 1M, a flow chart illustrating a method of using an LED array is shown. In step 180, a first voltage may be provided to a first pixel of the LED array. In step 182, a second voltage may be provided to a second pixel of the LED array. The first pixel and the second pixel may be separated by a first trench extending to the substrate. In step 184, a third voltage may be provided to a third pixel of the LED array. The second pixel and the third pixel may be separated by a second trench extending to the substrate.

Referring now to fig. 1N, a flow diagram illustrating a method of forming a device is shown. In step 190, one or more LEDs and one or more tunnel junctions may be formed on the substrate. In step 192, a first trench may be formed through the one or more tunnel junctions and the one or more LEDs to define a first pixel and a second pixel. The first trench may extend to the substrate. In optional step 194, a second trench may be formed through the one or more tunnel junctions and the one or more LEDs to define a second pixel and a third pixel.

Fig. 2A is a diagram of an LED device 200 in an example embodiment. LED device 200 may include a substrate 202, an active layer 204, a wavelength converting layer 206, and a primary optic 208. In other embodiments, the LED device may not include a wavelength converter layer and/or primary optics.

As shown in fig. 2A, the active layer 204 may be adjacent to the substrate 202 and emit light when excited. Suitable materials for forming the substrate 202 and the active layer 204 include sapphire, SiC, GaN, silicone, and more particularly may be composed of group III-V semiconductors (including, but not limited to, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb), group II-VI semiconductors (including, but not limited to, ZnS, ZnSe, CdSe, CdTe), group IV semiconductors (including, but not limited to, Ge, Si, SiC, and mixtures or alloys thereof).

The wavelength conversion layer 206 may be remote from, proximate to, or directly above the active layer 204. Active layer 204 emits light into wavelength-converting layer 206. Wavelength conversion layer 206 is used to further modify the wavelength of light emitted by active layer 204. LED devices that include a wavelength conversion layer are commonly referred to as phosphor converted LEDs ("PCLEDs"). The wavelength conversion layer 206 may comprise any luminescent material, such as, for example, phosphor particles in a transparent or translucent binder or matrix, or ceramic phosphor elements that absorb light of one wavelength and emit light of a different wavelength.

Primary optic 208 may be on or over one or more layers of LED device 200 and allows light from active layer 204 and/or wavelength-converting layer 206 to pass through primary optic 208. The primary optic 208 may be a lens or package configured to protect one or more layers and at least partially shape the output of the LED device 200. The primary optic 208 may include a transparent and/or translucent material. In an example embodiment, light via the primary optic may be emitted based on a Lambertian distribution pattern. It will be appreciated that one or more properties of the primary optic 208 may be modified to produce a light distribution pattern that is different from a lambertian distribution pattern.

Fig. 2B shows a cross-sectional view of an illumination system 220 in an example embodiment, the illumination system 220 comprising an LED array 210 with pixels 201A, 201B, and 201C and a secondary optic 212. The LED array 210 includes pixels 201A, 201B, and 201C, each pixel including a respective wavelength converting layer 206B, active layer 204B, and substrate 202B. The LED array 210 may be a monolithic LED array fabricated using wafer-level processing techniques, a micro LED having a sub-500 micron size, or the like. Pixels 201A, 201B, and 201C in LED array 210 may be formed using array segmentation or alternatively using pick and place techniques.

The space 203 shown between one or more pixels 201A, 201B, and 201C of the LED device 200B may include an air gap or may be filled with a material, such as a metal material, which may be a contact (e.g., an n-contact).

Secondary optic 212 may include one or both of lens 209 and waveguide 207. It will be appreciated that although secondary optics are discussed in accordance with the illustrated example, in an example embodiment, secondary optics 212 may be used to propagate incident light (diverging optics) or to concentrate incident light into a collimated beam (collimating optics). In an example embodiment, the waveguide 207 may be a concentrator and may have any suitable shape to concentrate light, such as a parabolic shape, a conical shape, a beveled shape, and the like. Waveguide 207 may be coated with a dielectric material, a metallization layer, or the like for reflecting or redirecting incident light. In alternative embodiments, the lighting system may not include one or more of the following: wavelength-converting layer 206B, primary optics 208B, waveguide 207, and lens 209.

The lens 209 may be formed of any suitable transparent material, such as, but not limited to, SiC, alumina, diamond, and the like, or combinations thereof. The lens 209 may be used to modify the light beam input into the lens 209 so that the output beam from the lens 209 will efficiently meet desired photometric specifications. Further, the lens 209 may serve one or more aesthetic purposes, such as by determining the bright and/or non-bright appearance of the p 201A, 201B, and/or 201C of the LED array 210.

Fig. 3 is a top view of an electronic board 310 of an integrated LED lighting system according to an embodiment. In alternative embodiments, two or more electronic boards may be used for the LED lighting system. For example, the LED array may be on a separate electronic board, or the sensor module may be on a separate electronic board. In the illustrated example, the electronic board 310 includes a power module 312, a sensor module 314, a connection and control module 316, and an LED attachment area 318 reserved for attaching an LED array to a substrate 320.

Substrate 320 may be any board capable of mechanically supporting and providing electrical coupling to electrical components, electronic components, and/or electronic modules using electrically conductive connectors, such as traces, pads, vias, and/or wires. The power module 312 may include electrical and/or electronic components. In an example embodiment, the power module 312 includes an AC/DC conversion circuit, a DC/DC conversion circuit, a dimming circuit, and an LED driver circuit.

The sensor module 314 may include sensors as needed for the application in which the LED array is to be implemented.

The connection and control module 316 may include a system microcontroller and any type of wired or wireless module configured to receive control inputs from external devices.

As used herein, the term module may refer to electrical and/or electronic components disposed on a separate circuit board that may be soldered to one or more electronic boards 310. However, the term module may also refer to electrical and/or electronic components that provide similar functionality, but which may be individually soldered to one or more circuit boards in the same area or in different areas.

Fig. 4A is a top view of an electronic board 310 with an LED array 410, in one embodiment, the LED array 410 attached to a substrate 320 at an LED device attachment area 318. The electronic board 310 together with the LED array 410 represents the LED system 400A. In addition, the power module 312 receives a voltage input at Vin 497 and a control signal from the connection and control module 316 through trace 418B, and provides a drive signal to the LED array 410 through trace 418A. The LED array 410 is turned on and off via a drive signal from the power module 312. In the embodiment shown in fig. 4A, connection and control module 316 receives sensor signals from sensor module 314 over trace 418C.

Figure 4B illustrates one embodiment of a two channel integrated LED lighting system having electronic components mounted on both surfaces of circuit board 499. As shown in fig. 4B, the LED lighting system 400B includes a first surface 445A having inputs to receive the dimmer signal and the AC power signal and an AC/DC converter circuit 412 mounted thereon. The LED system 400B includes a second surface 445B having a dimmer interface circuit 415, DC- DC converter circuits 440A and 440B, a connection and control module 416 (a wireless module in this example) having a microcontroller 472, and an LED array 410 mounted thereon. The LED array 410 is driven by two independent channels 411A and 411B. In alternative embodiments, a single channel may be used to provide a drive signal to the LED array, or any number of multiple channels may be used to provide a drive signal to the LED array.

The LED array 410 may include two sets of LED devices. In an example embodiment, the LED devices of group a are electrically coupled to the first channel 411A, and the LED devices of group B are electrically coupled to the second channel 411B. Each of the two DC- DC converters 440A and 440B may provide a respective drive current via a single channel 411A and 411B, respectively, for driving a respective set of LEDs a and B in the LED array 410. The LEDs in one of the groups of LEDs may be configured to emit light having a different color point than the LEDs in the second group of LEDs. By controlling the current and/or duty cycle applied by the individual DC/ DC converter circuits 440A and 440B via the single channels 411A and 411B, respectively, the control of the composite color point of the light emitted by the LED array 410 can be adjusted over a range. Although the embodiment shown in fig. 4B does not include a sensor module (as described in fig. 3 and 4A), alternative embodiments may include a sensor module.

The illustrated LED lighting system 400B is an integrated system in which the LED array 410 and circuitry for operating the LED array 410 are provided on a single electronic board. Connections between modules on the same surface of circuit board 499 may be electrically coupled by surface or sub-surface interconnects, such as traces 431, 432, 433, 434, and 435 or metallization (not shown), for exchanging, for example, voltage, current, and control signals between modules. Connections between modules on opposite surfaces of circuit board 499 may be electrically coupled by through-board interconnects, such as vias and metallization (not shown).

According to an embodiment, an LED system may be provided in which the LED array is on an electronic board separate from the driver and control circuitry. According to other embodiments, the LED system may have an array of LEDs together with some electronics on an electronic board separate from the driver circuit. For example, an LED system may include an LED module and a power conversion module located on an electronic board separate from the LED array.

According to an embodiment, the LED system may comprise a multi-channel LED driver circuit. For example, the LED module may include embedded LED calibration and setting data, and, for example, three sets of LEDs. One of ordinary skill in the art will recognize that any number of LED groups may be used consistent with one or more applications. The individual LEDs within each group may be arranged in series or in parallel and may provide light having different color points. For example, warm white light may be provided by a first set of LEDs, cool white light may be provided by a second set of LEDs, and neutral white light may be provided by a third set.

Fig. 5 shows an example system 550 that includes an application platform 560, LED systems 552 and 556, and secondary optics 554 and 558. The LED system 552 generates a light beam 561 shown between arrows 561a and 561 b. LED system 556 may produce a beam 562 between arrows 562a and 562 b. In the embodiment shown in fig. 5, light emitted from LED system 552 passes through secondary optic 554, and light emitted from LED system 556 passes through secondary optic 558. In an alternative embodiment, light beams 561 and 562 do not pass through any secondary optics. The secondary optic may be or may include one or more light guides. One or more of the light guides may be edge-lit or may have an interior opening defining an interior edge of the light guide. The LED systems 552 and/or 556 may be inserted into the interior opening of the one or more light guides such that they inject light into the interior edge (interior opening light guide) or the exterior edge (edge lit light guide) of the one or more light guides. The LEDs in LED systems 552 and/or 556 can be arranged around the circumference of a base that is part of the light guide. According to an embodiment, the base may be thermally conductive. According to an embodiment, the base may be coupled to a heat dissipation element disposed above the light guide. The heat dissipating element may be arranged to receive heat generated by the LED via the thermally conductive substrate and dissipate the received heat. The one or more light guides can allow the light emitted by the LED systems 552 and 556 to be shaped in a desired manner, such as, for example, with a gradient, a chamfered distribution, a narrow distribution, a wide distribution, an angular distribution, and so forth.

In an example embodiment, the system 550 may be a mobile phone with a camera flash system, indoor residential or commercial lighting, outdoor lights such as street lighting, automobiles, medical devices, AR/VR devices, and robotic devices. The integrated LED lighting system shown in fig. 3, LED system 400A shown in fig. 4A, illustrates LED systems 552 and 556 in an example embodiment.

In an example embodiment, the system 550 may be a mobile phone of a camera flash system, indoor residential or commercial lighting, outdoor lights such as street lighting, automobiles, medical devices, AR/VR devices, and robotic devices. The LED system 400A shown in fig. 4A and the LED system 400B shown in fig. 4B illustrate the LED systems 552 and 556 in an example embodiment.

As discussed herein, the application platform 560 may provide power to the LED systems 552 and/or 556 via the power bus via line 565 or other suitable input. Additionally, the application platform 560 may provide input signals via lines 565 for the operation of the LED system 552 and the LED system 556, which may be based on user input/preferences, sensed readings, preprogrammed or autonomously determined outputs, and the like. The one or more sensors may be internal or external to the housing of the application platform 560.

In various embodiments, the application platform 560 sensors and/or the LED systems 552 and/or 556 sensors may collect data, such as visual data (e.g., LIDAR data, IR data, data collected via a camera, etc.), audio data, distance-based data, movement data, environmental data, and the like, or combinations thereof. The data may relate to a physical item or entity, such as an object, a person, a vehicle, etc. For example, sensing equipment may collect object proximity data for ADAS/AV based applications, which may prioritize detection and follow-up actions based on detection of physical items or entities. Data may be collected based on, for example, emitting an optical signal (such as an IR signal) by LED systems 552 and/or 556 and collecting data based on the emitted optical signal. Data may be collected by a component different from the component that emits the optical signal used for data collection. Continuing with this example, the sensing equipment may be located on an automobile and may use a Vertical Cavity Surface Emitting Laser (VCSEL) to emit a light beam. One or more sensors may sense a response to the emitted light beam or any other suitable input.

In an example embodiment, application platform 560 may represent an automobile, and LED system 552 and LED system 556 may represent automobile headlights. In various embodiments, the system 550 may represent an automobile with a steerable light beam, where the LEDs may be selectively activated to provide steerable light. For example, an array of LEDs may be used to define or project a shape or pattern, or to illuminate only selected portions of a roadway. In an example embodiment, infrared camera or detector pixels within LED systems 552 and/or 556 may be sensors that identify portions of a scene (road, crosswalk, etc.) that need to be illuminated.

Having described embodiments in detail, those skilled in the art will appreciate that given the present description, modifications may be made to the embodiments described herein without departing from the spirit of the inventive concept. Therefore, it is not intended that the scope of the invention be limited to the specific embodiments illustrated and described.