阅读说明：本技术 一种垂直腔面发射激光器及其制备方法 (Vertical cavity surface emitting laser and preparation method thereof ) 是由 杨健 曾评伟 范纲维 于 2021-06-16 设计创作，主要内容包括：本发明提供一种垂直腔面发射激光器及其制备方法,涉及半导体器件技术领域,包括：衬底,在衬底上依次设置N型分布式布拉格反射镜、量子阱、P型分布式布拉格反射镜和接触层,在P型分布式布拉格反射镜靠近量子阱的一侧设置氧化图案层,氧化图案层用于定义出射光束的窗口区域,在接触层上形成环形凹槽,环形凹槽自接触层延伸至P型分布式布拉格反射镜内,且环形凹槽在氧化图案层上的正投影至少部分位于窗口区域内,并且在环形凹槽内填充导电材料,可以通过导电材料的设置限制P型分布式布拉格反射镜的反射光范围,从而达到进一步缩小窗口区域出射光束的范围,改善出射光束在目标区域的光斑模态。(The invention provides a vertical cavity surface emitting laser and a preparation method thereof, relating to the technical field of semiconductor devices and comprising the following steps: the light-emitting diode comprises a substrate, wherein an N-type distributed Bragg reflector, a quantum well, a P-type distributed Bragg reflector and a contact layer are sequentially arranged on the substrate, an oxidation pattern layer is arranged on one side, close to the quantum well, of the P-type distributed Bragg reflector and used for defining a window area of an emergent light beam, an annular groove is formed in the contact layer and extends into the P-type distributed Bragg reflector from the contact layer, at least part of the orthographic projection of the annular groove on the oxidation pattern layer is located in the window area, and a conductive material is filled in the annular groove, so that the range of the reflected light of the P-type distributed Bragg reflector can be limited through the arrangement of the conductive material, the range of the emergent light beam in the window area is further reduced, and the light spot mode of the emergent light beam in a target area is improved.)

1. A vertical cavity surface emitting laser, comprising: the light source comprises a substrate, wherein an N-type distributed Bragg reflector, a quantum well, a P-type distributed Bragg reflector and a contact layer are sequentially arranged on the substrate, an oxidation pattern layer is arranged on one side, close to the quantum well, of the P-type distributed Bragg reflector and used for defining a window area of an emergent light beam, an annular groove is formed on one side, far away from the quantum well, of the contact layer, the annular groove extends into the P-type distributed Bragg reflector from the contact layer, a conductive material is filled in the annular groove, and an orthographic projection area of the annular groove on the substrate is at least partially located in an orthographic projection area of the window area on the substrate.

2. A vertical cavity surface emitting laser according to claim 1, wherein an orthographic projection area of said annular groove on said substrate covers an orthographic projection area of said oxide pattern layer on said substrate.

3. A vertical cavity surface emitting laser according to claim 1, wherein a first electrode layer is provided on said contact layer.

4. A vertical cavity surface emitting laser according to any one of claims 1 to 3, wherein said electrically conductive material is a metal material.

5. A vertical cavity surface emitting laser according to any one of claims 1 to 3, wherein a second electrode layer is provided on the back surface of said substrate.

6. A vertical cavity surface emitting laser according to any one of claims 1 to 3, wherein said annular groove has a thickness of 0.1 μm to 4 μm.

7. A method for fabricating a vertical cavity surface emitting laser, the method comprising:

sequentially forming an N-type distributed Bragg reflector, a quantum well, a P-type distributed Bragg reflector and a contact layer on a substrate;

sequentially etching the contact layer and the P-type distributed Bragg reflector to form an annular groove, wherein the annular groove extends from the contact layer into the P-type distributed Bragg reflector;

filling a conductive material in the annular groove;

and forming an oxidation pattern layer on one side of the P-type distributed Bragg reflector close to the quantum well through oxidation, wherein the oxidation pattern layer is used for defining a window area of an emergent light beam, and the orthographic projection area of the annular groove on the substrate is at least partially positioned in the orthographic projection area of the window area on the substrate.

8. A method for manufacturing a vertical cavity surface emitting laser according to claim 7, wherein an orthographic projection area of said annular groove on said substrate covers an orthographic projection area of said oxide pattern layer on said substrate.

9. A method for fabricating a vertical cavity surface emitting laser according to claim 7, wherein after filling said annular groove with a conductive material, said method further comprises:

and forming a first electrode layer on the contact layer.

10. A method for fabricating a vertical cavity surface emitting laser according to claim 7, further comprising: and forming a second electrode layer on the back surface of the substrate.

Technical Field

The invention relates to the technical field of semiconductor devices, in particular to a vertical cavity surface emitting laser and a preparation method thereof.

Background

Semiconductor lasers are used in many imaging applications requiring high power illumination, and Vertical Cavity Surface Emitting Lasers (VCSELs) are widely used in many semiconductor lasers due to their advantages in low power, high frequency, etc., and manufacturing advantages.

The existing VCSEL structure is generally provided with an oxidation layer, and an oxidation hole is formed in the oxidation layer to achieve the effect of current limitation, but the current density in the oxidation hole is uneven, so that the light spot mode is poor, and in order to improve the light spot mode, the oxidation hole is usually reduced to improve, so that the current density is increased, and the heating is increased.

Disclosure of Invention

The present invention is directed to a vertical cavity surface emitting laser and a method for fabricating the same, which can improve a mode of a light spot by destroying a portion of a DBR mirror, and avoid an increase in heat generation.

In order to achieve the above purpose, the embodiment of the present invention adopts the following technical solutions:

in one aspect of the embodiments of the present invention, a vertical cavity surface emitting laser is provided, including: the light source comprises a substrate, wherein an N-type distributed Bragg reflector, a quantum well, a P-type distributed Bragg reflector and a contact layer are sequentially arranged on the substrate, an oxidation pattern layer is arranged on one side, close to the quantum well, of the P-type distributed Bragg reflector, the oxidation pattern layer is used for defining a window area of an emergent light beam, an annular groove is formed in one side, far away from the quantum well, of the contact layer, the annular groove extends into the P-type distributed Bragg reflector from the contact layer, a conductive material is filled in the annular groove, and an orthographic projection area of the annular groove on the substrate is at least partially located in an orthographic projection area of the window area on the substrate.

Optionally, an orthographic projection area of the annular groove on the substrate covers an orthographic projection area of the oxidation pattern layer on the substrate.

Optionally, a first electrode layer is disposed on the contact layer.

Optionally, the conductive material is a metal material.

Optionally, a second electrode layer is disposed on the back side of the substrate.

Optionally, the thickness of the annular groove is 0.1 μm to 4 μm.

In another aspect of the embodiments of the present invention, a method for manufacturing a vertical cavity surface emitting laser is provided, where the method includes: sequentially forming an N-type distributed Bragg reflector, a quantum well, a P-type distributed Bragg reflector and a contact layer on a substrate; sequentially etching the contact layer and the P-type distributed Bragg reflector to form an annular groove, wherein the annular groove extends from the contact layer into the P-type distributed Bragg reflector; filling a conductive material in the annular groove; and forming an oxidation pattern layer on one side of the P-type distributed Bragg reflector close to the quantum well through oxidation, wherein the oxidation pattern layer is used for defining a window area of the emergent light beam, and the orthographic projection area of the annular groove on the substrate is at least partially positioned in the orthographic projection area of the window area on the substrate.

Optionally, an orthographic projection area of the annular groove on the substrate covers an orthographic projection area of the oxidation pattern layer on the substrate.

Optionally, after the conductive material is filled in the annular groove, the method further includes: a first electrode layer is formed on the contact layer.

Optionally, the method further comprises: and forming a second electrode layer on the back surface of the substrate.

The beneficial effects of the invention include:

the invention provides a vertical cavity surface emitting laser and a preparation method thereof, wherein the preparation method comprises the following steps: the light source comprises a substrate, wherein an N-type distributed Bragg reflector, a quantum well, a P-type distributed Bragg reflector and a contact layer are sequentially arranged on the substrate, an oxidation pattern layer is arranged on one side, close to the quantum well, of the P-type distributed Bragg reflector, the oxidation pattern layer comprises a window area used for defining an emergent light beam, an annular groove is formed on one side, far away from the quantum well, of the contact layer, the annular groove extends into the P-type distributed Bragg reflector from the contact layer and is not in contact with the oxidation pattern layer, the orthographic projection area of the annular groove on the substrate is at least partially located in the orthographic projection area of the window area on the substrate, and a conductive material is filled in the annular groove, so that the reflected light range of the P-type distributed Bragg reflector can be limited through the arrangement of the conductive material, the range of the emergent light beam of the window area is further reduced, and the range of the emergent light beam of the device is more concentrated, and improving the spot mode of the emergent light beam in the target area to be closer to the ideal Gaussian mode. Because the filling material in the annular groove is the conductive material, the conductive property of the conductive material is utilized while the light spot mode is improved, the current density is prevented from being increased, the heat productivity is reduced, and the good heat dispersion performance of the device is convenient to realize.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

Fig. 1 is a schematic flow chart of a method for manufacturing a vertical cavity surface emitting laser according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a VCSEL according to an embodiment of the invention;

FIG. 3 is a second schematic structural diagram of a VCSEL according to an embodiment of the invention;

FIG. 4 is a third schematic structural diagram of a VCSEL according to an embodiment of the invention;

FIG. 5 is a fourth schematic structural diagram of a VCSEL according to an embodiment of the present invention;

FIG. 6 is a fifth schematic structural diagram of a VCSEL according to an embodiment of the present invention;

FIG. 7 is a sixth schematic structural view of a VCSEL provided in an embodiment of the present invention;

fig. 8 is a seventh schematic structural diagram of a vertical cavity surface emitting laser according to an embodiment of the present invention.

Icon: 100-a substrate; 110-N type distributed bragg reflector; 120-quantum well; 130-P type distributed bragg reflector; 131-an annular groove; 140-a contact layer; 150-a metal material; 160-a first electrode layer; 170-a second electrode layer; 180-oxidizing the patterned layer; 200-photoresist.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. It should be noted that, in the case of no conflict, various features in the embodiments of the present invention may be combined with each other, and the combined embodiments are still within the scope of the present invention.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

In the description of the present invention, the terms "first", "second", "third", and the like are used only for distinguishing the description, and are not intended to indicate or imply relative importance.

In an aspect of the embodiments of the present invention, there is provided a vertical cavity surface emitting laser, as shown in fig. 7, including: the light source comprises a substrate 100, wherein an N-type distributed Bragg reflector 110, a quantum well 120, a P-type distributed Bragg reflector 130 and a contact layer 140 are sequentially arranged on the substrate 100, an oxidation pattern layer 180 is arranged on one side, close to the quantum well 120, of the P-type distributed Bragg reflector 130, the oxidation pattern layer 180 defines a window region of an outgoing light beam on the P-type distributed Bragg reflector 130, an annular groove 131 is formed on one side, far away from the quantum well 120, of the contact layer 140, the annular groove 131 extends into the P-type distributed Bragg reflector 130 from the contact layer 140, a conductive material is filled in the annular groove 131, and an orthographic projection region, on the substrate 100, of the annular groove 131 is at least partially located in an orthographic projection region, on the substrate 100, of the window region.

For example, as shown in fig. 7, an N-type dbr 110, a quantum well 120, a P-type dbr 130, and a contact layer are sequentially disposed on a substrate 100, wherein the N-type dbr 110 may be a periodic structure formed by alternately arranging two materials with different refractive indexes in an ABAB manner, and an optical thickness of each material is 1/4 of a central reflection wavelength. Similarly, the P-type dbr 130 may be appropriately configured with reference to the N-type dbr 110. Therefore, the brightness of the emergent light beam can be effectively improved.

The quantum well 120 disposed between the N-type dbr 110 and the P-type dbr 130 may be used for stimulated radiation to generate a light beam, and then the light beam with high brightness is formed by the high reflectivity of the dbr and is emitted outward, so as to form a light spot in a target region. The quantum well 120 may be a single quantum well 120 or a multiple quantum well 120, which enables a device having a lower threshold, higher quantum efficiency, excellent temperature characteristics, and an extremely narrow line width.

In order to improve the quality of the light beam emitted by the device, the oxidation pattern layer 180 may be disposed on one side of the P-type dbr 130 close to the quantum well 120, and the oxidation pattern layer 180 may be formed by disposing a transition layer on one side of the P-type dbr 130 close to the quantum well 120 and then oxidizing the side surface of the transition layer; the structure of the P-type dbr 130 itself may be used to form the oxide-containing high-resistance confinement region-oxide pattern layer 180 on the side of the P-type dbr 130 close to the quantum well 120 by side oxidation. In order to enable the P-type dbr 130 to form the oxide pattern layer 180 at a side close to the quantum well 120 by oxidation, the P-type dbr 130 may include a plurality of layers in which a layer closest to the quantum well 120 has a high al content so as to form the corresponding oxide pattern layer 180 during the oxidation. The distribution area of the current is limited through the oxidation pattern layer 180, so that the current can be conducted in a concentrated mode through the window area, light beams are emitted from the window area conveniently, and therefore threshold current of the device can be effectively reduced, and electro-optic conversion efficiency of the device can be effectively improved.

The annular grooves 131 are formed on the side of the contact layer 140 away from the quantum well 120, and the number of the annular grooves 131 is not limited, and may be, for example, two annular grooves 131 of an inner ring and an outer ring in fig. 3. The annular groove 131 can extend from the contact layer 140 into the P-type dbr 130 by etching, that is, the bottom wall of the annular groove 131 is located in the P-type dbr 130, and the bottom wall of the annular groove 131 is not in contact with the oxide pattern layer 180 (the conductive material or the space between the annular groove 131 and the oxide pattern layer 180 is also isolated by the P-type dbr 130 layer), and the annular groove 131 is at least partially located in the orthographic projection area of the substrate 100 in the window area in the orthographic projection area of the substrate 100, and then the annular groove 131 is filled with the conductive material to form an annular conductive layer in the annular groove 131, so that the reflective light range of the P-type dbr 130 can be limited by the arrangement of the conductive material, thereby further reducing the range of the outgoing light beam in the window area and further concentrating the range of the final outgoing light beam of the device, and improving the spot mode of the emergent light beam in the target area to be closer to the ideal Gaussian mode. Because the filling material in the annular groove 131 is a conductive material, the conductive property of the conductive material is utilized to avoid increasing the current density while improving the light spot mode, so that the increase of the heat productivity can be avoided, and the good heat dissipation performance of the device can be realized.

The substrate 100 may be a gallium arsenide substrate 100; the material of the N-type dbr 110 may be algan, and the element composition ratio thereof may be Al_xGa_(1-x)As; the material of the quantum well 120 may be a heterojunction structure formed of AlGaAs and InGaAs, e.g., In_xGa_(1-x)As/Al_xGa_(1-x)As; the material of the P-type DBR 130 may be AlGaAs, such as Al_xGa_(1-x)As。When the oxidized pattern layer 180 is formed directly on the side of the P-type dbr 130 close to the quantum well 120, a portion of the aluminum-containing component in the P-type dbr 130 may be oxidized to form an aluminum oxide layer through a side oxidation process, that is, the material of the oxidized pattern layer 180 is aluminum oxide, for example: al (Al)₂O₃。

The window region formed by oxidizing the pattern layer 180 may be various forms of a ring region, a circular region, a square region, and the like. By arranging the annular groove 131 and filling the conductive material in the annular groove 131 in a matching manner, and the orthographic projection part of the annular groove 131 on the substrate 100 is located in the window region, the light-shielding property of the conductive material can be matched to further reduce the actual light-emitting region of the device from the original window region to a reduced region, and the area of the reduced region is equal to the area of the window region minus the projection area in the window region occupied by the annular groove 131. Meanwhile, the conductive material in the annular groove 131 can conduct current, so that the problem of increased heat generation caused by increased current density can be avoided.

The orthographic projection part of the annular groove 131 formed on the substrate 100 is located in the window area, the shape located in the window area can be annular, and the center of the annular can coincide with the center of the window area, so that the light emitting range can be uniformly reduced, and a better light spot mode can be obtained.

As shown in fig. 7, the number of the annular grooves 131 may be multiple, and the inner diameters of the plurality of annular grooves 131 are different, so as to form a layout manner of a large sleeve and a small sleeve, and two adjacent annular grooves are distributed in a spaced manner. Of course, in another embodiment, as shown in fig. 8, the annular groove 131 may also be one, that is, an orthogonal projection area of the annular groove 131 on the substrate 100 covers an orthogonal projection area of the oxide pattern layer 180 on the substrate 100, that is, the annular groove 131 includes two parts, and an orthogonal projection of a first part on the substrate 100 is located in an orthogonal projection of a window area on the substrate 100, so that the window area can be further reduced by the conductive material filled in the first part of the annular groove 131, and the light extraction quality of the device is improved, and at the same time, an orthogonal projection of a second part on the substrate 100 completely covers an orthogonal projection of the oxide pattern layer 180 on the substrate 100, so that the second part completely covers all areas except the window area, and the device has better light extraction quality.

Optionally, as shown in fig. 7, a first electrode layer 160 may be further disposed on the contact layer 140, in order to enable the device to effectively emit light beams, a notch may be formed on the first electrode layer 160 at a position corresponding to the window region, and an edge position of the notch of the first electrode layer 160 may vertically correspond to an inner edge of the annular groove 131, so as to form a light exit channel with a reduced range. In addition, the first electrode layer 160 can be in contact connection with the conductive material in the annular groove 131, so that a better heat dissipation effect can be formed by using the first electrode layer 160, and the performance of the device is improved. The second electrode layer 170 may be provided on the back surface of the substrate 100, and the first electrode layer 160 and the second electrode layer 170 may be used as positive and negative electrodes of the device, for example, the first electrode layer 160 may be used as a P-type metal layer, the P-type metal layer may be used as a positive electrode, the second electrode layer 170 may be used as an N-type metal layer, and the N-type metal layer may be used as a negative electrode.

Alternatively, the conductive material may be a metal material 150, such as copper, aluminum, gold, or the like. The filling process of the conductive material may be formed by evaporation or electroplating.

Optionally, the thickness of the annular groove is 0.1 μm to 4 μm, so that the light emitting quality of the device can be further improved.

In another aspect of the embodiments of the present invention, as shown in fig. 1, a method for manufacturing a vertical cavity surface emitting laser is provided, the method including:

s010: and sequentially forming an N-type distributed Bragg reflector, a quantum well, a P-type distributed Bragg reflector and a contact layer on the substrate.

As shown in fig. 2, the N-type dbr 110, the quantum well 120, the P-type dbr 130, and the contact layer 140 are sequentially formed on the substrate 100 by epitaxial growth, thereby forming a basic structure of the device.

S020: and sequentially etching the contact layer and the P-type distributed Bragg reflector to form an annular groove, wherein the annular groove extends from the contact layer into the P-type distributed Bragg reflector.

After S010, as shown in fig. 3, a first prefabricated device structure is formed by photolithography, for example, photolithography, that is, first coating a photoresist 200 on a surface of the contact layer 140 away from the quantum well 120, opening an annular opening on the photoresist 200 by exposure and development, etching the contact layer 140 in the opening through photolithography to expose the P-type dbr 130 under the contact layer 140, and then continuing to etch the P-type dbr 130 in the opening and controlling an etching depth to make the P-type dbr 130 not to be etched through, so as to form an annular groove 131 penetrating through the contact layer 140 and extending into the P-type dbr 130 in the opening, as shown in fig. 3.

S030: and filling the annular groove with a conductive material.

As shown in fig. 4, the annular groove 131 is filled with a conductive material by electroplating or evaporation on the basis of the first prefabricated device structure to form an annular conductive layer, and the photoresist 200 is removed to form the device structure shown in fig. 5.

S040: and forming an oxidation pattern layer on one side of the P-type distributed Bragg reflector pattern layer close to the quantum well through oxidation, wherein the oxidation pattern layer is used for defining a window area of the emergent light beam, and the orthographic projection area of the annular groove on the substrate is at least partially positioned in the orthographic projection area of the window area on the substrate.

As shown in fig. 7, an oxidation pattern layer 180 is formed on a side of the P-type dbr 130 pattern layer close to the quantum well 120 through an oxidation process, for example: the peripheral region of the device is first subjected to photolithography, such as photolithography, so that the portion to be oxidized is exposed, and then, through side oxidation, the high-content aluminum layer on the side of the P-type dbr 130 close to the quantum well 120 is oxidized to form the oxidized pattern layer 180.

The distribution area of the current is limited through the oxidation pattern layer 180, so that the current can be conducted in a concentrated mode through the window area, light beams are emitted from the window area conveniently, and therefore threshold current of the device can be effectively reduced, and electro-optic conversion efficiency of the device can be effectively improved.

As shown in fig. 7 or fig. 8, an annular groove 131 and an oxide pattern layer 180 are respectively formed on two opposite side surfaces of the P-type dbr 130, and the annular groove 131 and the oxide pattern layer 180 are not in direct contact, that is, the P-type dbr 130 with a certain thickness is further provided between the annular groove 131 and the oxide pattern layer 180, and it is further required to make an orthographic projection area of the annular groove 131 at least partially located in an orthographic projection area of the window area, and fill a conductive material in the annular groove 131, so that a reflected light range of the P-type dbr 130 can be limited by the arrangement of the conductive material, thereby further reducing a range of an emitted light beam in the window area, making a range of a final emitted light beam of the device more concentrated, improving a spot mode of the emitted light beam in a target area, and making the spot mode of the emitted light beam closer to an ideal gaussian mode. Because the filling material in the annular groove 131 is a conductive material, the conductive property of the conductive material is utilized to avoid increasing the current density while improving the light spot mode, so that the increase of the heat productivity can be avoided, and the good heat dissipation performance of the device can be realized.

As shown in fig. 7, the annular groove 131 may be a plurality of annular grooves 131, that is, a plurality of annular grooves 131 have different inner diameters, are nested with each other centering on the window region, and are distributed in a spaced manner. Of course, in another embodiment, as shown in fig. 8, the annular groove 131 may also be one, that is, an orthogonal projection area of the annular groove 131 on the substrate 100 covers an orthogonal projection area of the oxide pattern layer 180 on the substrate 100, that is, the annular groove 131 includes two parts, and an orthogonal projection of a first part on the substrate 100 is located in an orthogonal projection on the window area substrate 100, so that the window area can be further reduced by the conductive material filled in the first part of the annular groove 131, and the light extraction quality of the device is improved, meanwhile, an orthogonal projection of a second part on the substrate 100 completely covers an orthogonal projection of the oxide pattern layer 180 on the substrate 100, so that the second part completely covers all areas except the window area, and thus the device has better light extraction quality.

Optionally, as shown in fig. 5, after the annular groove 131 is filled with the conductive material, the method further includes: as shown in fig. 6, the first electrode layer 160 is formed on the contact layer 140, so that the first electrode layer 160 is connected to the metal material 150 in the annular groove 131, and thus, a better heat dissipation effect can be achieved by using the first electrode layer 160, thereby improving the performance of the device. The second electrode layer 170 may be provided on the back surface of the substrate 100, and the first electrode layer 160 and the second electrode layer 170 may be used as positive and negative electrodes of the device, for example, the first electrode layer 160 may be used as a P-type metal layer, the P-type metal layer may be used as a positive electrode, the second electrode layer 170 may be used as an n-type metal layer, and the n-type metal layer may be used as a negative electrode.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.