阅读说明：本技术 光子晶体面射型激光结构 (Photonic crystal surface emitting laser structure ) 是由 卢廷昌 洪国彬 陈立人 赵天行 于 2021-08-09 设计创作，主要内容包括：一种光子晶体面射型激光结构包含基板、N型披覆层、主动层、折射率匹配层以及光子晶体结构。N型披覆层设置在基板上。主动层设置在N型披覆层上。折射率匹配层设置在N型披覆层上,并环绕主动层。折射率匹配层电性绝缘,且折射率匹配层的等效折射率与主动层的等效折射率实质上相同。光子晶体结构设置在主动层以及折射率匹配层上。藉由上述结构配置,可减小激光的发散角以及阈值电流。(A photonic crystal surface-emitting laser structure includes a substrate, an N-type cladding layer, an active layer, a refractive index matching layer and a photonic crystal structure. The N-type cladding layer is arranged on the substrate. The active layer is disposed on the N-type cladding layer. The refractive index matching layer is arranged on the N-type cladding layer and surrounds the active layer. The refractive index matching layer is electrically insulated, and the equivalent refractive index of the refractive index matching layer is substantially the same as that of the active layer. The photonic crystal structure is disposed on the active layer and the index matching layer. By the above structural arrangement, the divergence angle of the laser light and the threshold current can be reduced.)

1. A photonic crystal surface-emitting laser structure, comprising:

a first substrate;

an N-type cladding layer disposed on the first substrate;

the active layer is arranged on the N-type cladding layer;

a refractive index matching layer disposed on the N-type cladding layer and surrounding the active layer, wherein the refractive index matching layer is electrically insulated and has an equivalent refractive index substantially the same as that of the active layer; and

a photonic crystal structure disposed on the active layer and the index matching layer.

2. The photonic crystal surface-emitting laser structure of claim 1, wherein the index matching layer is transparent to light emitted by the active layer.

3. The photonic crystal surface emitting laser structure of claim 1, wherein a lateral length of the active layer is less than a lateral length of the photonic crystal structure.

4. The photonic crystal surface emitting laser structure of claim 1, wherein a cross-sectional area of the active layer is smaller than a cross-sectional area of the photonic crystal structure.

5. The photonic crystal surface emitting laser structure of claim 1, wherein the active layer is located within a vertical projection region of the photonic crystal structure on the N-type cladding layer.

6. The photonic crystal surface emitting laser structure of claim 1, wherein the index matching layer is at least partially located within a perpendicular projection region of the photonic crystal structure on the N-type cladding layer.

7. The photonic crystal surface emitting laser structure of claim 1, wherein the lateral length of the active layer is 6 to 10 μm.

8. The photonic crystal surface emitting laser structure of claim 1, wherein the index matching layer contacts a side surface of the active layer.

9. The photonic crystal surface emitting laser structure of claim 1, wherein the active layer further has a top surface facing the photonic crystal structure and a bottom surface facing the N-type cladding layer, the side surface being connected between the top surface and the bottom surface, the index matching layer being separated from the top surface and the bottom surface of the active layer.

10. The photonic crystal surface emitting laser structure of claim 1, wherein the active layer is substantially cylindrical.

11. The photonic crystal surface emitting laser structure of claim 1, further comprising an electron confinement layer overlying the active layer and the index matching layer.

12. The photonic crystal surface emitting laser structure of claim 1, further comprising a P-type cladding layer disposed on the photonic crystal structure and a second substrate disposed on the P-type cladding layer.

13. The photonic crystal surface-emitting laser structure of claim 12, further comprising a metal electrode disposed on a side of the second substrate away from the P-type cladding layer and contacting a surface of the second substrate away from the P-type cladding layer.

14. The photonic crystal surface emitting laser structure of claim 1, further comprising a transparent conductive layer disposed on the photonic crystal structure.

15. The photonic crystal surface-emitting laser structure of claim 14, further comprising a metal electrode disposed on a side of the transparent conductive layer away from the photonic crystal structure and contacting a surface of the transparent conductive layer away from the photonic crystal structure.

16. The photonic crystal surface-emitting laser structure of claim 1, further comprising a metal electrode disposed on a side of the first substrate away from the N-type cladding layer and contacting a surface of the first substrate away from the N-type cladding layer.

17. The photonic crystal surface emitting laser structure of claim 1, wherein the photonic crystal structure comprises a plurality of periodic holes.

18. The photonic crystal surface-emitting laser structure of claim 17, wherein the first substrate, the N-type cladding layer and the active layer are aligned along a first direction, and the periodic holes are aligned along a plane perpendicular to the first direction.

19. The photonic crystal surface-emitting laser structure of claim 17, wherein the periodic holes have a cross-sectional shape of a circle, a quadrangle or a hexagon.

20. The photonic crystal surface emitting laser structure of claim 1, wherein the active layer comprises a quantum well.

Technical Field

The present disclosure relates to a photonic crystal surface emitting laser structure.

Background

Laser has wide application in medical treatment, optical communication, industrial processing and other fields. The problems of an existing laser structure that a divergence angle (divergence angle) is too large and a threshold current is too large are solved.

Disclosure of Invention

In view of the above, an object of the present disclosure is to provide a photonic crystal surface emitting laser structure with a small divergence angle and a small threshold current.

To achieve the above objects, according to some embodiments of the present disclosure, a photonic crystal surface emitting laser structure includes a first substrate, an N-type cladding layer, an active layer, an index matching layer, and a photonic crystal structure. The N-type cladding layer is arranged on the first substrate. The active layer is disposed on the N-type cladding layer. The refractive index matching layer is arranged on the N-type cladding layer and surrounds the active layer. The refractive index matching layer is electrically insulated, and the equivalent refractive index of the refractive index matching layer is substantially the same as that of the active layer. The photonic crystal structure is disposed on the active layer and the index matching layer.

In one or more embodiments of the present disclosure, the index matching layer is light transmissive for light emitted by the active layer.

In one or more embodiments of the present disclosure, the lateral length of the active layer is less than the lateral length of the photonic crystal structure.

In one or more embodiments of the present disclosure, the active layer has a cross-sectional area that is less than the cross-sectional area of the photonic crystal structure.

In one or more embodiments of the present disclosure, the active layer is located within a vertical projection area of the photonic crystal structure on the N-type cladding layer.

In one or more embodiments of the present disclosure, the refractive index matching layer is at least partially located within a perpendicular projection region of the photonic crystal structure on the N-type cladding layer.

In one or more embodiments of the present disclosure, the lateral length of the active layer is 6 to 10 microns.

In one or more embodiments of the present disclosure, the index matching layer contacts a side of the active layer.

In one or more embodiments of the present disclosure, the active layer further has a top surface facing the photonic crystal structure and a bottom surface facing the N-type cladding layer, and the side surface of the active layer is connected between the top surface and the bottom surface. The index matching layer is separated from the top and bottom surfaces of the active layer.

In one or more embodiments of the present disclosure, the active layer is substantially cylindrical.

In one or more embodiments of the present disclosure, the photonic crystal surface emitting laser structure further includes an electron confinement layer covering the active layer and the refractive index matching layer.

In one or more embodiments of the present disclosure, the photonic crystal surface emitting laser structure further includes a P-type cladding layer and a second substrate. The P-type cladding layer is disposed on the photonic crystal structure, and the second substrate is disposed on the P-type cladding layer.

In one or more embodiments of the present disclosure, the photonic crystal surface emitting laser structure further includes a metal electrode. The metal electrode is arranged on one side of the second substrate far away from the P-type cladding layer and contacts the surface of the second substrate far away from the P-type cladding layer.

In one or more embodiments of the present disclosure, the photonic crystal surface emitting laser structure further includes a transparent conductive layer disposed on the photonic crystal structure.

In one or more embodiments of the present disclosure, the photonic crystal surface emitting laser structure further includes a metal electrode. The metal electrode is arranged on one side of the transparent conducting layer, which is far away from the photonic crystal structure, and contacts the surface of the transparent conducting layer, which is far away from the photonic crystal structure.

In one or more embodiments of the present disclosure, the photonic crystal surface emitting laser structure further includes a metal electrode. The metal electrode is arranged on one side of the first substrate far away from the N-type cladding layer and contacts the surface of the first substrate far away from the N-type cladding layer.

In one or more embodiments of the present disclosure, the photonic crystal structure includes a plurality of periodic holes.

In one or more embodiments of the present disclosure, the periodic holes are arranged along a plane perpendicular to a direction in which the first substrate, the N-type cladding layer, and the active layer are arranged.

In one or more embodiments of the present disclosure, the cross-sectional shape of the periodic holes is circular, quadrilateral or hexagonal.

In one or more embodiments of the present disclosure, the active layer includes a quantum well.

In summary, the photonic crystal surface-emitting laser structure of the present disclosure includes an index matching layer disposed around the active layer, the index matching layer is electrically insulated, and the equivalent refractive index of the index matching layer is substantially the same as the equivalent refractive index of the active layer. By the above structural arrangement, the divergence angle of the laser light and the threshold current can be reduced.

Drawings

In order to make the aforementioned and other objects, features, advantages and embodiments of the present disclosure more comprehensible, the following description is to be read in conjunction with the accompanying drawings:

fig. 1 is a top view of a photonic crystal surface-emitting laser structure according to an embodiment of the present disclosure.

Fig. 2 is an enlarged perspective view of the photonic crystal surface-emitting laser structure shown in fig. 1 in a region M.

FIG. 3 is a cross-sectional view of the photonic crystal surface-emitting laser structure shown in FIG. 1 along line 1-1'.

Fig. 4 to 8 are cross-sectional views of the photonic crystal surface-emitting laser structure shown in fig. 3 at various stages of manufacturing.

FIG. 9 is a cross-sectional view of a photonic crystal surface emitting laser structure according to another embodiment of the present disclosure.

Reference numerals:

100,200 photonic crystal surface-emitting laser structure 101 first electrode

102 second electrode 110 first substrate

120N-type cladding layer 130 active layer

140 index matching layer 150 photonic crystal structure

150A semiconductor layer 151 base

152 periodic holes 160P-type cladding layer

170, a second substrate 180, an electron confining layer

290 transparent conductive layer LB laser beam

M area W1, W2 transverse length

X is a second direction and Y is a first direction

Detailed Description

In order to make the disclosure more complete and complete, reference is made to the accompanying drawings and the following description of various embodiments. The elements in the drawings are not to scale and are provided merely to illustrate the present disclosure. Numerous specific details are set forth in order to provide a thorough understanding of the present disclosure, however, it will be apparent to one of ordinary skill in the relevant art that the present disclosure may be practiced without one or more of these specific details and that, therefore, these specific details should not be used to limit the present disclosure.

Please refer to fig. 1 to 3. Fig. 1 is a top view illustrating a photonic crystal surface-emitting laser structure 100 according to an embodiment of the present disclosure, fig. 2 is an enlarged perspective view illustrating the photonic crystal surface-emitting laser structure 100 shown in fig. 1 in a region M, and fig. 3 is a cross-sectional view illustrating the photonic crystal surface-emitting laser structure 100 shown in fig. 1 along a line 1-1'. The photonic crystal surface-emitting laser structure 100 includes a first substrate 110, an N-type cladding layer 120, an active layer 130, an index matching layer 140, a photonic crystal structure 150, a P-type cladding layer 160, and a second substrate 170 stacked along a first direction Y. The first substrate 110 is, for example, a semiconductor substrate, and may include gallium arsenide (GaAs) or other suitable semiconductor materials. The N-type cladding layer 120 is disposed on the first substrate 110. The active layer 130 and the index matching layer 140 are disposed on the N-type cladding layer 120. In some embodiments, the active layer 130 includes quantum wells configured to emit light when the photonic crystal surface-emitting laser structure 100 is powered on.

In some embodiments, the N-type cladding layer 120 includes gallium arsenide (GaAs), indium gallium arsenide (InGaAs), indium gallium arsenide phosphide (InGaAsP), aluminum arsenide (AlAs), aluminum gallium indium arsenide (AlGaInAs), aluminum gallium indium phosphide (AlGaInP), aluminum gallium arsenide (AlGaAs), indium gallium arsenide nitride (InGaNAs), gallium antimonide (GaAsSb), gallium antimonide (GaSb), indium phosphide (InP), indium arsenide (InAs), gallium phosphide (GaP), aluminum phosphide (AlP), gallium nitride (GaN), aluminum gallium nitride (AlGaN), indium gallium nitride (InGaN), aluminum indium gallium nitride (AlInGaN), other suitable semiconductor materials, or any combination thereof.

As shown in fig. 1 to 3, the photonic crystal structure 150 is disposed on the active layer 130 and the index matching layer 140. The light emitted from the active layer 130 resonates in the photonic crystal structure 150 to generate a laser beam LB, and the laser beam LB exits from the top of the photonic crystal surface-emitting laser structure 100 along the first direction Y.

As shown in fig. 1-3, in some embodiments, photonic crystal structure 150 includes a base 151 and a plurality of periodic voids 152. The base 151 may comprise gallium arsenide (GaAs) or other suitable semiconductor material, the periodic holes 152 are formed on a side of the base 151 away from the active layer 130 and the index matching layer 140, and the periodic holes 152 are aligned in a second direction X substantially perpendicular to the first direction Y. In some embodiments, the periodic holes 152 are arranged along a plane perpendicular to the first direction Y. In some embodiments, the cross-sectional shape of the periodic holes 152 may be circular, quadrilateral, or hexagonal.

As shown in fig. 1 to 3, a P-type cladding layer 160 is disposed on the photonic crystal structure 150, and a second substrate 170 is disposed on the P-type cladding layer 160. The second substrate 170 may comprise a P-type semiconductor material, such as P-GaAs.

In some embodiments, the P-type cladding layer 160 includes gallium arsenide (GaAs), indium gallium arsenide (InGaAs), indium gallium arsenide phosphide (InGaAsP), aluminum arsenide (AlAs), aluminum gallium indium arsenide (AlGaInAs), aluminum gallium indium phosphide (AlGaInP), aluminum gallium arsenide (AlGaAs), indium gallium arsenide nitride (InGaNAs), gallium antimonide (GaAsSb), gallium antimonide (GaSb), indium phosphide (InP), indium arsenide (InAs), gallium phosphide (GaP), aluminum phosphide (AlP), gallium nitride (GaN), aluminum gallium nitride (AlGaN), indium gallium nitride (InGaN), aluminum indium gallium nitride (AlInGaN), other suitable semiconductor materials, or any combination thereof.

As shown in fig. 1 to 3, the index matching layer 140 is disposed around the active layer 130. The active layer 130 is, for example, a cylinder, and the active layer 130 is circular in a top view. The index matching layer 140 is separated from the bottom surface (i.e., the surface of the active layer 130 facing the N-type cladding layer 120) and the top surface (i.e., the surface of the active layer 130 facing the photonic crystal structure 150) of the active layer 130, and contacts the side surface (i.e., the surface of the active layer 130 connected between the top surface and the bottom surface) of the active layer 130. The index matching layer 140 is electrically insulating so that when the photonic crystal surface emitting laser structure 100 is energized, current passes only through the active layer 130. The index matching layer 140 does not actively emit light nor absorb light. In addition, the equivalent refractive index of the index matching layer 140 is substantially the same as the equivalent refractive index of the active layer 130. By the above structural arrangement, the divergence angle of the laser light and the threshold current can be reduced.

In some embodiments, the index matching layer 140 comprises a dielectric material or a non-conductive or high-impedance semiconductor material (e.g., undoped semiconductor material, or doped semiconductor material such as GaN doped with Fe). In some embodiments, the index matching layer 140 is light transmissive for light emitted by the active layer 130.

As shown in fig. 1 to 3, in some embodiments, the area of the cross section of the active layer 130 (i.e., the section of the active layer 130 perpendicular to the first direction Y) is smaller than the area of the cross section of the photonic crystal structure 150 (i.e., the section of the photonic crystal structure 150 perpendicular to the first direction Y). When the photonic crystal surface emitting laser structure 100 is powered on, current is injected into the active layer 130 with a smaller range, but the light emitting region can be extended to the photonic crystal structure 150 with a larger range. In some embodiments, the ratio of the cross-sectional area of the index matching layer 140 to the cross-sectional area of the active layer 130 falls within the range of 1.5 to 100.

As shown in fig. 1 to 3, in some embodiments, the lateral length W1 of the active layer 130 is smaller than the lateral length W2 of the photonic crystal structure 150, wherein the lateral length refers to the length in the second direction X. In some embodiments, the lateral length W1 of the active layer 130 is 6 to 10 microns. In embodiments where the active layer 130 is cylindrical, the lateral length W1 corresponds to the diameter of the active layer 130.

As shown in fig. 1 to 3, in some embodiments, the active layer 130 is located within a vertical projection area of the photonic crystal structure 150 on the N-type cladding layer 120, wherein the vertical projection area is an area projected along a direction opposite to the first direction Y. In some embodiments, the index matching layer 140 disposed around the active layer 130 is at least partially located within a perpendicular projection area of the photonic crystal structure 150 on the N-type cladding layer 120.

As shown in fig. 1 to 3, in some embodiments, the photonic crystal surface-emitting laser structure 100 further includes an electron confinement layer 180, and the electron confinement layer 180 covers the active layer 130 and the refractive index matching layer 140 and is located between the photonic crystal structure 150 and the active layer 130 and the refractive index matching layer 140.

As shown in fig. 1 to 3, in some embodiments, the photonic crystal surface-emitting laser structure 100 further includes a first electrode 101 and a second electrode 102. The first electrode 101 is disposed on a side of the first substrate 110 away from the N-type cladding layer 120, and contacts a surface of the first substrate 110 away from the N-type cladding layer 120. The second electrode 102 is disposed on a side of the second substrate 170 away from the P-type cladding layer 160 and contacts a surface of the second substrate 170 away from the P-type cladding layer 160. In some embodiments, the first electrode 101 and the second electrode 102 are metal electrodes. In some embodiments, the second electrode 102 comprises a ring structure having an opening at the center for the laser beam LB to pass through.

In some embodiments, the first electrode 101 and the second electrode 102 comprise indium (In), tin (Sn), aluminum (Al), gold (Au), platinum (Pt), zinc (Zn), germanium (Ge), silver (Ag), lead (Pb), palladium (Pd), copper (Cu), gold beryllium (AuBe), germanium beryllium (BeGe), nickel (Ni), lead tin (PbSn), chromium (Cr), gold zinc (AuZn), titanium (Ti), tungsten (W), titanium Tungsten (TiW), other suitable conductive materials, or any combination thereof.

The following describes a method for manufacturing the photonic crystal surface-emitting laser structure 100.

Fig. 4 to 8 are cross-sectional views of the photonic crystal surface-emitting laser structure 100 shown in fig. 3 at various stages of manufacturing. The method for manufacturing the photonic crystal surface-emitting laser structure 100 includes steps S1 to S11.

As shown in fig. 4, first, in step S1, the first substrate 110, the N-type cladding layer 120 and the active layer 130 are stacked. The first substrate 110, the N-type cladding layer 120 and the active layer 130 are arranged along the first direction Y, and the active layer 130 covers the upper surface of the N-type cladding layer 120. In some embodiments, the step S1 includes forming the first substrate 110, the N-type cladding layer 120, and the active layer 130 stacked in an epitaxial growth manner.

As shown in fig. 5, next, in step S3, an index matching layer 140 disposed around the active layer 130 is formed. In some embodiments, the step S3 includes etching the outer edge of the active layer 130 formed in the step S2, and forming the index matching layer 140 around the active layer 130 by epitaxial growth. In some embodiments, step S3 includes performing quantum well intermixing (quantum well intermixing) on the active layer 130 to form the index matching layer 140.

As shown in FIG. 6, next, in step S5, an electron confinement layer 180 and a semiconductor layer 150A (e.g., P-GaAs) are formed on the active layer 130 and the index matching layer 140 in a stacked manner. The electron confining layer 180 and the semiconductor layer 150A are arranged along the first direction Y, and the semiconductor layer 150A covers the top surface of the electron confining layer 180. In some embodiments, step S5 includes forming the electron confinement layer 180 and the semiconductor layer 150A stacked on the active layer 130 and the index matching layer 140 by epitaxial growth.

As shown in fig. 7, next, in step S7, a photonic crystal structure 150 is formed in the semiconductor layer 150A. In some embodiments, step S7 includes removing a portion of the semiconductor layer 150A to form the periodic voids 152 of the photonic crystal structure 150. The remaining semiconductor layer 150A serves as a base 151 of the photonic crystal structure 150. In some embodiments, step S7 includes forming the periodic holes 152 of the photonic crystal structure 150 by etching or photolithography to remove portions of the semiconductor layer 150A.

As shown in FIG. 8, next, in step S9, a P-type cladding layer 160 and a second substrate 170 (e.g., P-GaAs) are formed on the photonic crystal structure 150 in a stacked manner. The P-type cladding layer 160 and the second substrate 170 are arranged along the first direction Y, and the second substrate 170 covers the upper surface of the P-type cladding layer 160. In some embodiments, the step S9 includes forming the P-type cladding layer 160 and the second substrate 170 stacked on the photonic crystal structure 150 by epitaxial growth.

Referring back to fig. 3, finally, in step S11, a first electrode 101 and a second electrode 102 are formed, wherein the first electrode 101 is disposed on a side of the first substrate 110 away from the N-type cladding layer 120 and contacts a surface of the first substrate 110 away from the N-type cladding layer 120. The second electrode 102 is disposed on a side of the second substrate 170 away from the P-type cladding layer 160 and contacts a surface of the second substrate 170 away from the P-type cladding layer 160. In some embodiments, step S11 includes forming the first electrode 101 on the surface of the first substrate 110 away from the N-type cladding layer 120 and forming the second electrode 102 on the surface of the second substrate 170 away from the P-type cladding layer 160 by deposition.

Referring to fig. 9, a cross-sectional view of a photonic crystal surface-emitting laser structure 200 according to another embodiment of the present disclosure is shown. The difference between this embodiment and the embodiment shown in fig. 3 is that the photonic crystal surface-emitting laser structure 200 includes a transparent conductive layer 290 instead of the P-type cladding layer 160 and the second substrate 170. The transparent conductive layer 290 covers the side of the photonic crystal structure 150 away from the active layer 130, and the second electrode 102 is disposed on the transparent conductive layer 290 and contacts the surface of the transparent conductive layer 290 away from the photonic crystal structure 150.

In some embodiments, the method for manufacturing the photonic crystal surface emitting laser structure 200 includes: after the photonic crystal structure 150 is formed, a transparent conductive layer 290 is deposited on the side of the photonic crystal structure 150 away from the active layer 130.

In some embodiments, the transparent conductive layer 290 includes Indium Tin Oxide (ITO), zinc oxide (ZnO), aluminum gallium indium tin oxide (AlGaInSnO), Aluminum Zinc Oxide (AZO), tin oxide (SnO)₂) Indium oxide (In)₂O₃) Zinc tin oxide (SnZnO), Graphene (Graphene), other suitable transparent conductive materials, or any combination thereof. The material has good penetration rate in visible light wave band and infrared light wave band, so that laser beams LB can be emitted conveniently.

In summary, the photonic crystal surface-emitting laser structure of the present disclosure includes an index matching layer disposed around the active layer, the index matching layer is electrically insulated, and the equivalent refractive index of the index matching layer is substantially the same as the equivalent refractive index of the active layer. By the above structural arrangement, the divergence angle of the laser light and the threshold current can be reduced.

Although the present disclosure has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the disclosure, and therefore, the scope of the disclosure should be determined by that which is defined in the appended claims.