阅读说明：本技术 基于二氧化钛光子晶体的氮化镓基面激光器及制备方法 (Gallium nitride substrate laser based on titanium dioxide photonic crystal and preparation method thereof ) 是由 刘启发 刘美玉 许涵蕾 徐嘉琪 皇甫甜 于 2020-05-29 设计创作，主要内容包括：本发明公开了一种基于二氧化钛光子晶体的面发射型氮化镓基激光器及制备方法,包括蓝宝石衬底层、n-GaN层、n-AlGaN层、波导n-GaN层、n-电极、InGaN/GaN成对组成的多层量子阱有源层、p-GaN层、p-电极、TiO<Sub>2</Sub>光子晶体层。本发明采用了TiO<Sub>2</Sub>作为光子晶体层的材料,实现了对光场模式分布的有益调控,能实现在光子晶体内的高效耦合,更有利于激光器低阈值的实现。采用了在晶片表面生长制备光子晶体层,相比传统的在晶片材料内部引入光子晶体的方法更为简单方便,降低了制备加工的难度。(The invention discloses a surface emitting gallium nitride-based laser based on titanium dioxide photonic crystals and a preparation method thereof 2 A photonic crystal layer. The invention adopts TiO 2 As the material of the photonic crystal layer, the photonic crystal realizes the beneficial regulation and control of the light field mode distribution, can realize the high-efficiency coupling in the photonic crystal, and is more beneficial to the realization of the low threshold value of the laser. Compared with the traditional method of introducing the photonic crystal into the wafer material, the method has the advantages that the photonic crystal layer is grown and prepared on the surface of the wafer, and the difficulty of preparation and processing is reduced.)

1. The gallium nitride-based surface emitting laser based on titanium dioxide photonic crystal is characterized by comprising

A sapphire substrate layer;

the n-GaN layer is positioned on the sapphire substrate layer;

an n-AlGaN layer located on the n-GaN layer;

the waveguide n-GaN layer is positioned on the n-AlGaN layer;

an MQWs layer located on the waveguide n-GaN layer;

a p-GaN layer located over the waveguide MQWs layer;

TiO₂a photonic crystal layer located over the p-GaN layer;

the n-electrode is arranged on the surface of the waveguide n-GaN layer;

and the p-electrode is arranged on the surface of the p-GaN layer.

2. The gallium nitride-based surface emitting laser based on titanium dioxide photonic crystals according to claim 1, wherein the TiO is₂The photonic crystal layer is formed by mixing TiO₂The layer is etched through to form a periodic hole structure, the lattice type of the photonic crystal is a square lattice or a triangular lattice or a honeycomb type lattice, the period is 150-250 nm, and the hole radius is 10-100 nm.

3. The titanium dioxide photonic crystal-based gallium nitride-based surface emitting laser according to claim 1, wherein the n-electrode and the p-electrode are designed by a peripheral ring electrode structure, a central solid electrode structure, a corner electrode structure and an optical pumping structure.

4. The gallium nitride-based surface emitting laser based on the titanium dioxide photonic crystal according to claim 1, wherein the n-AlGaN layer has a thickness of 300 to 1000 nm and an Al content of 10 to 20%.

5. The titanium dioxide photonic crystal-based gallium nitride-based surface emitting laser according to claim 1, wherein the thickness of the n-GaN layer is 1-8 μm, the thickness of the waveguide n-GaN layer is 20-250 nm, and the thickness of the p-GaN layer is 20-250 nm.

6. The method for manufacturing a titanium dioxide photonic crystal based gallium nitride basal plane emission type laser according to claims 1 to 5, wherein the starting material is a sapphire-based GaN active wafer, comprising the steps of:

step (1): growing TiO with a certain thickness on the surface of a sapphire-based GaN active wafer₂;

Step (2): in TiO₂Surface advancingPerforming electron beam lithography to form a photonic crystal mask structure;

and (3): etching TiO by dry method or wet method₂Forming a hole structure and removing electron beam resist of electron beam lithography;

and (4): by photolithography and TiO₂Etching process to leave TiO in the set area₂A photonic crystal layer;

and (5): preparing a p electrode in a set area on the surface of the p-GaN by adopting photoetching and lift off processes;

and (6): etching the set region to the n-GaN layer from top to bottom by adopting photoetching and III-V etching processes;

and (7): and preparing the n electrode in the set region on the surface of the n-GaN by adopting photoetching and lift off processes.

Technical Field

The invention discloses a titanium dioxide photonic crystal-based gallium nitride substrate laser and a preparation method thereof, and relates to the field of active photonic devices.

Background

The Photonic Crystal Surface Emitting Laser (PCSEL) has the advantages of large emitting area, high energy, small divergence angle, good single mode, etc., and the short wavelength/blue laser based on gallium nitride (GaN) material has wide application and can realize excellent performance and application prospect in the fields of high-speed communication, display systems, high-density memories, etc.

However, the current reports of gallium nitride-based photonic crystal surface emitting lasers are based on burying air holes in GaN to form Photonic Crystals (PCs), or etching active quantum well layers from surface GaN to obtain photonic crystals. The first method has complex process and higher difficulty, and cannot obtain better coupling strength of the light field and the PC area; the second method causes damage to the GaN system and the active layer, and typically only optically pumped lasers can be realized.

Disclosure of Invention

Aiming at the defects in the background technology, the invention provides the gallium nitride based laser based on the titanium dioxide photonic crystal and the preparation method thereof, and the gallium nitride based laser based on the titanium dioxide photonic crystal has the advantages of simple structure, excellent performance and simple preparation.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows: a GaN basal plane emitting laser based on titanium dioxide photonic crystal comprises

A sapphire substrate layer;

the n-GaN layer is positioned on the sapphire substrate layer;

an n-AlGaN layer located on the n-GaN layer;

the waveguide n-GaN layer is positioned on the n-AlGaN layer;

the MQWs layer is positioned on the waveguide n-GaN layer and is a multilayer quantum well active layer formed by InGaN/GaN in pairs;

a p-GaN layer located over the waveguide MQWs layer;

TiO₂a photonic crystal layer located over the p-GaN layer;

the n-electrode is arranged on the surface of the waveguide n-GaN layer;

and the p-electrode is arranged on the surface of the p-GaN layer.

Further, TiO₂The photonic crystal layer is formed by mixing TiO₂The layers being etched through to form periodic voidsThe structure, the lattice is a tetragonal lattice, a triangular lattice or a honeycomb type lattice, the period is 150-250 nm, and the hole radius is 10-100 nm.

Furthermore, the n-electrode and the p-electrode are designed by adopting a peripheral annular electrode structure, a central solid electrode structure, a corner electrode structure and an optical pumping structure;

the structure of the peripheral annular electrode is as follows: the TiO is₂The photonic crystal layer, the p-GaN layer, the MQWs layer and the waveguide n-GaN layer are designed in a circular structure, and the TiO layer₂The diameters of the photonic crystal layer, the p-GaN layer and the waveguide n-GaN layer are sequentially increased, the diameters of the p-GaN layer and the MQWs layer are the same, and the p-electrode is arranged on the TiO₂Around the photonic crystal layer, an n-electrode is around the p-GaN layer and the MQWs layer.

The central solid electrode structure is as follows: the TiO is₂The photonic crystal layer, the p-GaN layer, the MQWs layer and the waveguide n-GaN layer are designed in a circular structure, and the TiO layer₂The diameters of the photonic crystal layer, the p-GaN layer and the waveguide n-GaN layer are sequentially increased, the diameters of the p-GaN layer and the MQWs layer are the same, and the p-electrode is arranged on the TiO₂The photonic crystal layer is centered, and the n-electrode is around the p-GaN layer and the MQWs layer.

The corner electrode structure is as follows: the TiO is₂The photonic crystal layer, the p-GaN layer, the MQWS layer and the waveguide n-GaN layer are of square structures, the p-electrode is arranged at the corner position of the p-GaN layer and is of a solid structure with a certain size, and the n-electrode is arranged on the n-GaN layer and is positioned at the position diagonally opposite to the p-electrode and is of a solid structure with a certain size.

Furthermore, the thickness of the n-AlGaN layer is 300-1000 nm, and the Al content is 10% -20%.

Further, the thickness of the n-GaN layer is 1-8 mu m, the thickness of the waveguide n-GaN layer is 20-250 nm, and the thickness of the p-GaN layer is 20-250 nm.

The preparation method of the gallium nitride basal plane emission type laser based on the titanium dioxide photonic crystal comprises the following steps:

step (1): growing GaN active wafer, and depositing TiO with certain thickness on the surface₂Then, preparing GaN-PCSEL by micro-nano processing technology from top to bottom on TiO₂Surface-assisted electron beamPhotoetching to form a photonic crystal mask structure;

step (2): etching TiO by dry method or wet method₂Forming a hole structure and removing electron beam resist of electron beam lithography;

and (3): by photolithography and TiO₂Etching process to leave TiO in the set area₂A photonic crystal layer;

and (4): preparing a p electrode in a set area on the surface of the p-GaN by adopting photoetching and lift off processes;

and (5): etching the set region to the n-GaN layer from top to bottom by adopting photoetching and III-V etching processes;

and (6): and preparing the n electrode in the set region on the surface of the n-GaN by adopting photoetching and lift off processes.

The working principle is as follows: when the light frequency emitted by the active layer (MQWs layer) meets the edge band gap condition of the photonic crystal, the wavelength resonates in the plane of the photonic crystal to generate standing waves, the resonance of the standing waves in the plane can interact with the active layer, so that gain is formed, the number of particles is inverted, laser is generated, and meanwhile, the out-of-plane vertical emission of the laser is realized due to the first-order Bragg diffraction of the photonic crystal.

Advantageous effects

1. The AlGaN layer and the photonic crystal layer are used as the cladding layers to form a waveguide-like structure taking the active layer as the center, so that the basic mode can be well limited, and a foundation is laid for the high coupling strength of the optical field in the photonic crystal and the active layer.

2. The invention adopts TiO₂As the material of the photonic crystal layer, the photonic crystal realizes the beneficial regulation and control of the light field mode distribution, can realize the high-efficiency coupling in the photonic crystal, and is more beneficial to the realization of the low threshold value of the laser.

3. Compared with the traditional method of introducing the photonic crystal into the wafer material, the method for preparing the photonic crystal layer by growing the photonic crystal layer on the surface of the wafer is simpler and more convenient, and the difficulty of preparation and processing is reduced.

Drawings

FIG. 1 is a side view of the structure of the present invention;

FIG. 2 is a top view of the first embodiment of the present invention;

FIG. 3 is a top view of a second embodiment of the present invention;

fig. 4 is a top view of a third embodiment of the present invention.

Detailed Description

The following describes the embodiments in further detail with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.

As shown in FIG. 1, a GaN basal plane emission laser based on titanium dioxide photonic crystal comprises

A sapphire substrate layer;

the n-GaN layer is positioned on the sapphire substrate layer;

an n-AlGaN layer located on the n-GaN layer;

the waveguide n-GaN layer is positioned on the n-AlGaN layer;

an MQWs layer located on the waveguide n-GaN layer;

a p-GaN layer located over the waveguide MQWs layer;

TiO₂a photonic crystal layer located over the p-GaN layer;

the n-electrode is arranged on the surface of the waveguide n-GaN layer;

and the p-electrode is arranged on the surface of the p-GaN layer.

TiO₂The photonic crystal layer is formed by mixing TiO₂The layer is etched through to form a periodic hole structure, the lattice is a square lattice, a triangular lattice or a honeycomb type lattice, the period is 150-250 nm, and the hole radius is 10-100 nm.

The thickness of the n-AlGaN layer is 300-1000 nm, and the Al content is 10% -20%.

The thickness of the n-GaN layer is 1-8 mu m, the thickness of the waveguide n-GaN layer is 20-250 nm, and the thickness of the p-GaN layer is 20-250 nm.

The n-electrode and the p-electrode are designed by adopting a peripheral annular electrode structure, a central solid electrode structure, a corner electrode structure and an optical pumping structure;

as shown in fig. 2, said fourThe peripheral ring-shaped electrode structure is as follows: the TiO is₂The photonic crystal layer, the p-GaN layer, the MQWs layer and the waveguide n-GaN layer are designed in a circular structure, and the TiO layer₂The diameters of the photonic crystal layer, the p-GaN layer and the waveguide n-GaN layer are sequentially increased, the diameters of the p-GaN layer and the MQWs layer are the same, and the p-electrode is arranged on the TiO₂Around the photonic crystal layer, an n-electrode is around the p-GaN layer and the MQWs layer.

As shown in fig. 3, the central solid electrode structure is: the TiO is₂The photonic crystal layer, the p-GaN layer, the MQWs layer and the waveguide n-GaN layer are designed in a circular structure, and the TiO layer₂The diameters of the photonic crystal layer, the p-GaN layer and the waveguide n-GaN layer are sequentially increased, the diameters of the p-GaN layer and the MQWs layer are the same, and the p-electrode is arranged on the TiO₂The photonic crystal layer is centered, and the n-electrode is around the p-GaN layer and the MQWs layer.

As shown in fig. 4, the corner electrode structure is: the TiO is₂The photonic crystal layer, the p-GaN layer, the MQWS layer and the waveguide n-GaN layer are of square structures, the p-electrode is arranged at the corner position of the p-GaN layer and is of a solid structure with a certain size, and the n-electrode is arranged on the n-GaN layer and is positioned at the position diagonally opposite to the p-electrode and is of a solid structure with a certain size.

The preparation method of the gallium nitride basal plane emission type laser based on the titanium dioxide photonic crystal comprises the following steps:

step (1): in TiO₂Carrying out electron beam lithography on the surface to form a photonic crystal mask structure;

step (2): etching TiO by dry method or wet method₂Forming a hole structure and removing electron beam resist of electron beam lithography;

and (3): by photolithography and TiO₂Etching process to leave TiO in the set area₂A photonic crystal layer;

and (4): preparing a p electrode in a set area on the surface of the p-GaN by adopting photoetching and lift off processes;

and (5): etching the set region to the n-GaN layer from top to bottom by adopting photoetching and III-V etching processes to form a p-type island;

and (6): and preparing the n electrode in the set region on the surface of the n-GaN by adopting photoetching and lift off processes.

When the light frequency emitted by the active layer meets the edge band gap condition of the photonic crystal, the wavelength resonates in the photonic crystal plane to generate standing waves, the resonance of a light field in the plane can interact with the active layer, so that gain is formed, the number of particles is inverted, laser is generated, and meanwhile, the out-of-plane vertical emission of the laser is realized due to the first-order Bragg diffraction of the photonic crystal.

The AlGaN layer and the photonic crystal layer are used as the cladding layers to form a waveguide-like structure taking the active layer as the center, so that the basic mode can be well limited, and a foundation is laid for the high coupling strength of the optical field in the photonic crystal and the active layer.

The invention adopts TiO₂As the material of the photonic crystal layer, the photonic crystal realizes the beneficial regulation and control of the light field mode distribution, can realize the high-efficiency coupling in the photonic crystal, and is more beneficial to the realization of the low threshold value of the laser.

Compared with the traditional method of introducing the photonic crystal into the wafer material, the method for preparing the photonic crystal layer by growing the photonic crystal layer on the surface of the wafer is simpler and more convenient, and the difficulty of preparation and processing is reduced.

The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.