CN111933763B

CN111933763B - Epitaxial structure and manufacturing method thereof

Info

Publication number: CN111933763B
Application number: CN202010718509.5A
Authority: CN
Inventors: 范伟宏; 李东昇; 邬元杰; 蒋敏; 张成军
Original assignee: Xiamen Silan Advanced Compound Semiconductor Co Ltd
Current assignee: Xiamen Silan Advanced Compound Semiconductor Co Ltd
Priority date: 2020-07-23
Filing date: 2020-07-23
Publication date: 2022-04-26
Anticipated expiration: 2040-07-23
Also published as: CN111933763A

Abstract

An epitaxial structure and a method of fabricating the same, the epitaxial structure including a GaN electron supply layer over a substrate; the multi-quantum well layer is positioned above the GaN electron supply layer and comprises a plurality of barrier layers and a plurality of well layers which are alternately stacked; and a GaN hole supply layer located above the multiple quantum well layer, wherein the thickness of each barrier layer in the multiple quantum well layer is not more than 60 angstroms. The epitaxial structure forms an ultrathin barrier structure by controlling the thickness of the barrier layer in the multiple quantum well below 60 angstroms, thereby reducing the lattice mismatch stress of the well barrier, reducing the quantum confinement Stark effect of the multiple quantum well and further improving the electron hole recombination efficiency of the multiple quantum well.

Description

Epitaxial structure and manufacturing method thereof

Technical Field

The present disclosure relates to the field of semiconductor device fabrication, and more particularly, to an epitaxial structure and a method for fabricating the same.

Background

The compound semiconductor light-emitting element has the advantages of energy conservation, environmental protection, high luminous efficiency, easy regulation and control of color wavelength, small volume, long service life and the like, has become a mainstream illumination light source in the market, and is widely applied to various illumination and display fields such as household illumination, outdoor street lamp illumination, stage lamp illumination, traffic signal lamps, television backlight, mobile phone computer backlight, indoor display screens, car lamps and the like. In the prior art, nitride semiconductor light emitting devices have high luminous efficiency, and thus are increasingly used in the field of illumination.

It is desirable to further improve the structure and formation process of the semiconductor light emitting element so as to improve the multiple quantum well electron hole recombination efficiency and to improve the radiative recombination efficiency.

Disclosure of Invention

In view of the above, the present invention provides an epitaxial structure and a method for manufacturing the same, in which the barrier layer thickness in a multiple quantum well is controlled to be less than 60 angstroms to form an ultra-thin barrier structure, thereby reducing the lattice mismatch stress of the well barrier, reducing the quantum confinement stark effect of the multiple quantum well, and further improving the electron-hole recombination efficiency of the multiple quantum well.

According to an aspect of the present invention, there is provided an epitaxial structure comprising: a GaN electron supply layer over the substrate; a multi-quantum well layer located above the GaN electron supply layer and including a plurality of barrier layers and a plurality of well layers stacked alternately; and a GaN hole supply layer located above the multiple quantum well layer.

Preferably, each barrier layer in the multiple quantum well layer has a thickness of no more than 60 angstroms.

Preferably, the method further comprises the following steps: the stress release layer is positioned between the GaN electron supply layer and the multi-quantum well layer and comprises a plurality of barrier layers and a plurality of well layers which are alternately stacked; and the V-shaped depressions extend from the surface of the multi-quantum well layer to the substrate direction, and the barrier layers in the stress release layer and the barrier layers in the multi-quantum well layer form a composite thin barrier structure.

Preferably, each barrier layer in the stress release layer has a thickness of no more than 100 angstroms.

Preferably, the composite thin barrier structure regulates a stress state of the multiple quantum well layer, a structure of the V-shaped recess, and distribution of electrons and holes.

Preferably, the MQW layer is (In)_aGa_1-aN/Al_bGa_1-bN)_mThe value range of the period m includes 5 to 15, wherein In_aGa_1-aN layer as well layer, the In_aGa_1-aThe thickness of the N layer ranges from 30 to 40 angstroms inclusive, In_aGa_1-aIn the N layer, the value range of the In component a comprises 10 to 30 percent; al (Al)_bGa_1-bN layer as barrier layer, the Al layer_bGa_1-bThe thickness of the N layer is in the range of 40 to 60 angstroms, in said Al_bGa_1-bIn the N layer, the value range of the Al component b comprises 0 to 20 percent, and the Al_bGa_1-bThe doping concentration range of silicon in the N layer comprises 1E 15-1E 17cm^-3。

Preferably, the stress release layer is (In)_cGa_1-cN/Al_dGa_1-dN)_nThe value range of the period n comprises 1 to 30, wherein In_cGa_1-cN layer as well layer, the In_cGa_1-cThe thickness of the N layer is In the range of 5 to 30 angstroms, and the In is_cGa_1-cThe value of the In component c In the N layer is 0-30%, and c is less than a; al (Al)_dGa_1-dN layer as barrier layer, the Al layer_dGa_1-dThe thickness of the N layer is in the range of 10 to 100 angstroms, and the Al layer_dGa_1-dThe value of the Al component d in the N layer is 0 to 20 percent, and the Al component d is_dGa_1-dThe doping concentration range of silicon in the N layer comprises 5E 16-5E 18cm^-3。

Preferably, the composite thin barrier structure further comprises a transition layer, wherein the transition layer is located between the multiple quantum well layer and the stress release layer and used for adjusting the opening size of the V-shaped recess together with the composite thin barrier structure.

Preferably, the transition layer comprises Al_eGa_1-eN/In_fGa_1-fN/Al_gGa_1-gN layer of Al_eGa_1-eIn the N layer, the value range of the Al component e is 0 to 1 In_fGa_1-fIn the N layer, the value of the In component f is In the range of 0 to 1 In Al_gGa_1-gIn the N layer, the value range of the Al component g comprises 0 to 1, and the Al_eGa_1-eN layer, said In_fGa_1-fN layer and the Al_gGa_1-gThe thickness of N layers is in the range of 20-80 angstroms, and the doping concentration of silicon in the transition layer is in the range of 1E 17-1E 19cm^-3。

Preferably, at a surface of the multiple quantum well layer, an opening size of the plurality of V-shaped recesses ranges from 100 to 500 nm.

Preferably, the method further comprises the following steps: a first GaN high-carbon doped layer located above the GaN electron supply layer; and the second GaN high-carbon doping layer is positioned between the stress release layer and the first GaN high-carbon doping layer, wherein the carbon doping concentrations in the GaN electron supply layer, the first GaN high-carbon doping layer and the second GaN high-carbon doping layer are sequentially changed in a gradient manner.

Preferably, the doping concentration range of carbon in the GaN electron supply layer includes 5E16 to 1E17cm^-3The doping concentration range of carbon in the first GaN high-carbon doping layer comprises 1E 17-7E 17cm^-3The doping concentration range of carbon in the second GaN high-carbon doping layer comprises 7E 17-5E 18cm^-3。

Preferably, the doping concentration ranges of silicon in the first GaN high-carbon doping layer and the second GaN high-carbon doping layer both include 1E 18-1E 19cm^-3。

Preferably, the plurality of V-shaped recesses extend from the surface of the multiple quantum well layer into the first GaN high-carbon doped layer and/or the second GaN high-carbon doped layer and/or the stress relief layer.

Preferably, the method further comprises the following steps: an AlN buffer layer on the substrate; a GaN buffer layer on the AlN buffer layer; and an undoped GaN layer located between the GaN electron supply layer and the GaN buffer layer, wherein the AlN buffer layer and the GaN buffer layer constitute a double buffer layer structure for releasing lattice mismatch stress between the substrate and the undoped GaN layer.

Preferably, the AlN buffer layer has a thickness ranging from 100 to 500 angstroms and the GaN buffer layer has a thickness ranging from 30 to 100 angstroms, wherein the AlN buffer layer is a single crystal thin film layer.

Preferably, the undoped GaN layer has a thickness ranging from 3 to 5 μm, and is formed using a three-dimensional growth and a two-dimensional growth method to control the dislocation density in the undoped GaN layer to be within a range of 10⁶To 10⁹cm^-2Within.

Preferably, the density distribution range of the plurality of V-shaped recesses on the surface of the multiple quantum well layerComprises 10⁷To 10⁹cm^-2。

Preferably, the GaN electron supply layer includes: a first GaN electron supply layer on the undoped GaN; and a second GaN electron supply layer over the first GaN electron supply layer, wherein the first GaN electron supply layer has a thickness ranging from 0.5 to 1.5 μm, and the first GaN electron supply layer has a silicon doping concentration ranging from 1E18 to 5E18cm^-3A thickness of the second GaN electron supply layer ranging from 2 to 3 μm, a doping concentration of silicon in the second GaN electron supply layer ranging from 1E19 to 8E19cm^-3。

Preferably, the GaN-based light-emitting diode further comprises a hole blocking layer located between the first GaN electron supply layer and the second GaN electron supply layer, wherein the material of the hole blocking layer comprises Al_hGa_1-hN, thickness ranging from 20 to 200 angstroms, and silicon doping concentration in the hole blocking layer ranging from 1E18 to 2E19cm^-3Wherein the value range of h comprises 0 to 1.

Preferably, the method further comprises the following steps: the electron barrier layer is positioned on the multi-quantum well layer; a hole injection layer on the electron blocking layer; a hole-expanding layer between the hole-injecting layer and the GaN hole-supplying layer; and a contact layer on the GaN hole supply layer.

Preferably, the electron blocking layer includes Al_iGa_1-iN/AlN layer of Al_iGa_1-iThe value range of the Al component i in the N layer comprises 0 to 1, wherein Al is_iGa_1-iThe N layer thickness range includes 40 to 80 angstroms and the AlN layer thickness range includes 10 to 30 angstroms.

Preferably, the doping concentration range of Mg in the hole injection layer comprises 1E 19-1E 21cm^-3In a thickness range of 100 to 300 angstroms, wherein the hole injection layer comprises Al_jIn_kGa_1-j-kA N layer of Al_jIn_kGa_1-j-kIn the N layer, the value range of the Al component j is 0-60%, and the value range of the In component k is 0-40%.

Preferably, said cavityThe thickness of the hole expansion layer is 200-600 angstrom meters, the hole expansion layer comprises a GaN layer, and the doping concentration range of Mg in the hole expansion layer after secondary ion mass spectrometry comprises 1E 19-5E 19cm^-3。

Preferably, the GaN hole supply layer has a thickness ranging from 50 to 400 angstroms, and the doping concentration of Mg in the GaN hole supply layer ranges from 1E19 to 5E20cm^-3。

Preferably, the thickness of the contact layer ranges from 10 to 50 angstroms, and the doping concentration of Mg in the contact layer ranges from 5E19 to 1E21cm^-3。

Preferably, the plurality of V-shaped recesses are sequentially filled with the electron blocking layer, the hole injection layer, the hole expansion layer, and the GaN hole supply layer.

According to another aspect of the present invention, there is provided a method of fabricating an epitaxial structure, comprising: forming a GaN electron supply layer over a substrate; forming a multi-quantum well layer including a plurality of barrier layers and a plurality of well layers alternately stacked above the GaN electron supply layer; and forming a GaN hole supply layer over the multiple quantum well layer.

Preferably, the method further comprises the following steps: forming a stress release layer including a plurality of barrier layers and a plurality of well layers alternately stacked between the GaN electron supply layer and the multi-quantum well layer; and forming a plurality of V-shaped depressions, wherein the V-shaped depressions extend from the surface of the multiple quantum well layer to the substrate direction, and the barrier layers in the stress release layer and the barrier layers in the multiple quantum well layer form a composite thin barrier structure.

Preferably, the composite thin barrier structure is used for regulating and controlling the stress state of the multiple quantum well layer, the structure of the V-shaped recess and the distribution of electrons and holes.

Preferably, a transition layer is formed between the multiple quantum well layer and the stress release layer and used for adjusting the opening size of the V-shaped pit together with the composite thin barrier structure, wherein the opening size of the V-shaped pit is adjusted by adjusting the thickness of the barrier layer in the multiple quantum well layer and the stress release layer, the Al component and the forming condition respectively.

Preferably, the transition layer comprises Al_eGa_1-eN/In_fGa_1-fN/Al_gGa_1-gN layer of Al_eGa_1-eIn the N layer, the value range of the Al component e is 0 to 1 In_fGa_1-fIn group In N layerThe value of the part f is in the range of 0 to 1 in terms of Al_gGa_1-gIn the N layer, the value range of the Al component g comprises 0 to 1, and the Al_eGa_1-eN layer, said In_fGa_1-fN layer and the Al_gGa_1-gThe thickness of N layers is in the range of 20-80 angstroms, and the doping concentration of silicon in the transition layer is in the range of 1E 17-1E 19cm^-3。

Preferably, the plurality of V-shaped depressions have an opening size ranging from 100 to 500 nm.

Preferably, the method further comprises the following steps: forming an AlN buffer layer on the substrate; forming a GaN buffer layer on the AlN buffer layer; and forming an undoped GaN layer between the GaN electron supply layer and the GaN buffer layer, wherein the AlN buffer layer and the GaN buffer layer constitute a double buffer layer structure for releasing lattice mismatch stress between the substrate and the undoped GaN layer.

Preferably, the step of forming the AlN buffer layer includes growing an AlN single crystal thin film on the substrate using a magnetic chamber sputtering method, and a thickness of the AlN buffer layer includes a range of 100 to 500 angstroms.

Preferably, the step of forming the GaN buffer layer includes depositing a GaN material on the AlN buffer layer using a metal organic chemical vapor deposition method, the GaN buffer layer having a thickness ranging from 30 to 100 angstroms.

Preferably, the forming of the undoped GaN layer includes forming the undoped GaN layer on the GaN buffer layer using a two-step growth method of three-dimensional growth and two-dimensional growth to control a dislocation linear density range in the undoped GaN layer to 10⁶To 10⁹cm^-2Wherein a thickness of the undoped GaN layer ranges from 3 to 5 μm.

Preferably, the density distribution range of the plurality of V-shaped recesses at the surface of the MQW layer includes 10⁷To 10⁹cm^-2。

Preferably, the step of forming the GaN electron supply layer includes: forming a first GaN electron supply layer on the undoped GaN; and forming a second GaN electron supply layer over the first GaN electron supply layer, wherein the first GaN electron supply layer has a thickness ranging from 0.5 to 1.5 μm, and the first GaN electron supply layer has a silicon doping concentration ranging from 1E18 to 5E18cm^-3A thickness range of the second GaN electron supply layer includes 2 to 3 μm, and a Si doping concentration range in the second GaN electron supply layer includes 1E19 to 8E19cm^-3。

Preferably, the method further comprises forming a hole blocking layer between the first GaN electron supply layer and the second GaN electron supply layer, wherein the material of the hole blocking layer comprises Al_hGa_1-hN, thickness ranging from 20 to 200 angstroms, and silicon doping concentration in the hole blocking layer ranging from 1E18 to 2E19cm^-3Wherein the value range of h comprises 0 to 1.

Preferably, also includes; forming an electron blocking layer on the multi-quantum well layer; forming a hole injection layer on the electron blocking layer; forming a hole expansion layer between the hole injection layer and the GaN hole supply layer; and forming a contact layer on the GaN hole supply layer.

Preferably, the thickness of the hole expansion layer ranges from 200 to 600 angstroms, the hole expansion layer comprises a GaN layer, and the doping concentration range of Mg in the hole expansion layer after secondary ion mass spectrometry ranges from 1E19 to 5E19cm^-3。

According to the epitaxial structure and the manufacturing method thereof, the GaN electron supply layer, the GaN hole supply layer and the multiple quantum well layer sandwiched between the GaN electron supply layer and the GaN hole supply layer are formed on the substrate, the multiple quantum well layer comprises the multiple barrier layers and the multiple well layers which are alternately stacked, and therefore the semiconductor light-emitting element is formed.

Further, a stress release layer is formed between the GaN electron supply layer and the multiple quantum well layer, the stress release layer comprises a plurality of barrier layers and a plurality of well layers which are stacked alternately, a thin barrier structure is formed by controlling the thickness of the barrier layers in the stress release layer to be below 100 angstroms, lattice mismatch stress of a well barrier in the stress release layer is reduced, meanwhile, the barrier layers in the stress release layer and the barrier layers in the multiple quantum well layer form a composite thin barrier structure, and the composite thin barrier structure is used for regulating and controlling the stress state of the multiple quantum well, the structure of the V-shaped recess and electron hole distribution, so that the radiation recombination efficiency is improved. Further, the stress state of the multiple quantum well is regulated and controlled in the following way: 1. the multi-quantum well layer is formed by an ultrathin barrier with the thickness of 40-60 angstrom meters, the stress release layer is formed by a double-thin-barrier structure with the thickness of 10-100 angstrom meters, the size of a V-shaped recess is controlled, the Quantum Confinement Stark (QCSE) effect is reduced by controlling stress through the thin barrier, and the recombination efficiency of electron holes is improved; 2. the opening and the density of the V-shaped recess are controlled by the carbon doping content by adopting a high-carbon doping gradient layer (a first high-carbon doping layer and a second carbon doping layer or a combination of a plurality of carbon doping layers); the higher the carbon doping, the worse the crystal quality, so the carbon doping of the patent adopts a gradient gradual change mode, and the crystal quality and the opening of the V-shaped recess are considered.

Drawings

To more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly introduced below, and it is apparent that the drawings in the following description only relate to some embodiments of the present disclosure and do not limit the present disclosure.

Fig. 1 shows a schematic structural diagram of an epitaxial structure of an embodiment of the present invention.

Fig. 2-8 show cross-sectional views of a method of fabricating an epitaxial structure at various stages in accordance with an embodiment of the present invention.

Detailed Description

The invention will be described in more detail below with reference to the accompanying drawings. Like elements in the various figures are denoted by like reference numerals. For purposes of clarity, the various features in the drawings are not necessarily drawn to scale. In addition, certain well known components may not be shown. For simplicity, the epitaxial structure obtained after several steps can be described in one figure.

It will be understood that when a layer or region is referred to as being "on" or "over" another layer or region in describing the structure of the device, it can be directly on the other layer or region or intervening layers or regions may also be present. And, if the device is turned over, that layer, region, or regions would be "under" or "beneath" another layer, region, or regions.

If for the purpose of describing the situation directly on another layer, another area, the expression "directly on … …" or "on … … and adjacent thereto" will be used herein.

In the following description, numerous specific details of the invention, such as structure, materials, dimensions, processing techniques and techniques of the devices are described in order to provide a more thorough understanding of the invention. However, as will be understood by those skilled in the art, the present invention may be practiced without these specific details.

The present invention may be embodied in various forms, some examples of which are described below.

As shown in fig. 1, an epitaxial structure of an embodiment of the invention includes: the GaN light-emitting device includes a substrate 100, an AlN buffer layer 101, a GaN buffer layer 102, an undoped GaN layer 103, a first GaN electron supply layer 104, a hole blocking layer 105, a second GaN electron supply layer 106, a first GaN high-carbon doped layer 107, a second GaN high-carbon doped layer 108, a stress relief layer 109, a transition layer 110, a multiple quantum well layer 111, a plurality of V-pits (V-pits)112a to 112c, an electron blocking layer 113, a hole injection layer 114, a hole expansion layer 115, a GaN hole supply layer 116, and a contact layer 117.

In the present embodiment, the AlN buffer layer 101 is located on the Substrate 100, and the Substrate 100 includes one of a Sapphire Substrate, a silicon Substrate, an SiC Substrate, a Wet-patterned Sapphire Substrate (WPSS), and a Dry-patterned Sapphire Substrate (DPSS). In some preferred embodiments, substrate 100 is a Dry Patterned Sapphire Substrate (DPSS).

The AlN buffer layer 101 is a single crystal thin film, and the thickness of the AlN buffer layer 101 is in a range of 100 to 500 angstroms, preferably 200 angstroms. The GaN buffer layer 102 is located on the AlN buffer layer 101, and the thickness of the GaN buffer layer 102 ranges from 30 to 100 angstroms, preferably 60 angstroms. In the present embodiment, the AlN buffer layer 101 and the GaN buffer layer 102 constitute a double buffer structure to relieve lattice mismatch stress between the substrate 100 and the undoped GaN layer 103.

The undoped GaN layer 103 is located on the GaN buffer layer 102, and is made of unintentionally doped GaN. The thickness of the undoped GaN layer 103 ranges from 3 to 5 μm, preferably 4 μm. In the present embodiment, the undoped GaN layer 103 is formed using a three-dimensional (3D) growth and a two-dimensional (2D) growth method such that the dislocation density of the undoped GaN layer 103 is controlled to 10⁶To 10⁹cm^-2In the meantime. Wherein, the two-step growth method can effectively reduce lattice mismatch and obtain lower dislocation density.

A first GaN electron supply layer 104 is disposed on the undoped GaN layer 103, the first GaN electron supply layer 104 having a thickness ranging from 0.5 μm to 1.5 μm, wherein the first GaN electron supply layer 104 has a silicon doping concentration ranging from 1E18 to 5E18cm^-3The doping concentration range of carbon includes 5E16 to 1E17cm^-3。

In some preferred embodiments, the thickness of the first GaN electron supply layer 104 is 1 μm, and the doping concentration of silicon in the first GaN electron supply layer 104 is 2.3E18cm^-3The doping concentration of carbon is 6.8E16cm^-3。

The second GaN electron supply layer 106 is disposed above the first GaN electron supply layer 104, the second GaN electron supply layer 106 has a thickness ranging from 2 μm to 3 μm, wherein the second GaN electron supply layer 106 has a silicon doping concentration ranging from 1E19 to 8E19cm^-3The doping concentration range of carbon includes 5E16 to 1E17cm^-3。

In some preferred embodiments, the doping concentration of silicon in the second GaN electron supply layer 106 is 1.2E19cm^-3The doping concentration of carbon is 6.8E16cm^-3。

In the present embodiment, the first GaN electron supply layer 104 and the second GaN electron supply layer 106 constitute an electron supply layer for supplying electrons into the multiple quantum well layer 111.

The hole blocking layer 105 is located between the first GaN electron supply layer 104 and the second GaN electron supply layer 106. The material of the hole blocking layer 105 includes Al_hGa_1-hN, in a thickness range including 20 to 200 angstroms, and a silicon doping concentration range in the hole blocking layer 105 including 1E18 to 2E19cm^-3. Wherein the value range of h comprises 0 to 1.

The first GaN high-carbon doped layer 107 is located on the second GaN electron supply layer 106, and the doping concentration range of carbon in the first GaN high-carbon doped layer 107 includes 1E17 to 7E17cm^-3The doping concentration range of silicon comprises 1E 18-1E 19cm^-3. In some preferred embodiments, the doping concentration of carbon in the first GaN high-carbon doped layer 107 is 5.3E17cm^-3Doping concentration of silicon is 4.5E18cm^-3。

The second GaN high-carbon doped layer 108 is located on the first GaN high-carbon doped layer 107, and the doping concentration range of carbon in the second GaN high-carbon doped layer 108 includes 7E17 to 5E18cm^-3The doping concentration range of silicon comprises 1E 18-1E 19cm^-3. In some preferred embodiments, the doping concentration of carbon in the second GaN high-carbon doped layer 108 is 1.1E18cm^-3Doping concentration of silicon is 4.8E18cm^-3。

Wherein, the carbon doping content of the normal epitaxial layer is below 1E17, and the carbon doping content of the high-carbon doping layer is more than 1E 17.

In the present embodiment, the carbon doping concentrations in the GaN electron supply layer (including the first GaN electron supply layer 104 and the second GaN electron supply layer 106), the first GaN highly-carbon doped layer 107 and the second GaN highly-carbon doped layer 108 are sequentially changed in a gradient manner, so as to ensure the orderly opening of the V-shaped recess and the uniformity of the opening position.

The stress release layer 109 is located on the second GaN high-carbon doped layer 108The semiconductor device comprises a plurality of barrier layers and a plurality of well layers which are alternately stacked. The stress release layer 109 is (In)_cGa_1-cN/Al_dGa_1-dN)_nThe value range of the period n comprises 1 to 30, wherein In_cGa_1-cN layer as well layer not doped with Si, In_cGa_1-cThe thickness of the N layer is in the range of 5 to 30 angstroms, Al_dGa_1-dN layer as barrier layer, Al_dGa_1-dThe thickness of the N layer is in the range of 10 to 100 angstroms, Al_dGa_1-dThe value of Al component d in the N layer is 0-20%, Al_dGa_1-dThe doping concentration range of silicon in the N layer comprises 5E 16-5E 18cm^-3。

A transition layer 110 is disposed on the stress relief layer 109, the transition layer 110 comprising Al_eGa_1-eN/In_fGa_1-fN/Al_gGa_1-gN layer of Al_eGa_1-eIn the N layer, the value range of the Al component e is 0 to 1 In_fGa_1-fIn the N layer, the value of the In component f is In the range of 0 to 1 In Al_gGa_1-gIn the N layer, the value range of the Al component g comprises 0 to 1, and Al_eGa_1-eN layer, In_fGa_1-fN layer and Al_gGa_1-gThe N layers each have a thickness in the range of 20 to 80 angstroms and the transition layer 110 has a silicon doping concentration in the range of 1E17 to 1E19cm^-3。

The multiple quantum well layer 111 is located on the transition layer 110, and includes a plurality of barrier layers and a plurality of well layers that are alternately stacked. The multiple quantum well layer 111 is (In)_aGa_1-aN/Al_bGa_1-bN)_mThe value range of the period m is from 5 to 15, the range of the light-emitting wavelength lambda is from 420 to 520 nanometers, wherein In_aGa_1-aN layer as well layer not doped with Si, In_aGa_1-aThe thickness of the N layer ranges from 30 to 40 angstroms In_aGa_1-aIn the N layer, the value range of the In component a comprises 10 to 30 percent; al (Al)_bGa_1-bN layer as barrier layer, Al_bGa_1-bThe thickness of the N layer is in the range of 40 to 60 angstroms, in Al_bGa_1-bIn the N layerThe value range of the Al component b comprises 0 to 20 percent, and Al_bGa_1-bThe doping concentration range of silicon in the N layer comprises 1E 15-1E 17cm^-3。

In this embodiment, the value of the Al component in the stress release layer 109 and the mqw layer 111 can be reduced by directly reducing the Al content of the reaction, so as to achieve the purpose of reducing the lattice mismatch stress of the well barrier.

In the first embodiment, the period m of the mqw layer 111 is 10, the thickness of the well layer in the mqw layer 111 is 33 angstroms, the thickness of the barrier layer is 45 angstroms, the Al component b of the barrier layer is 2%, and the doping concentration of silicon in the barrier layer is 5E16cm^-3. The value of the Al component b of the barrier layer In the stress release layer 109 is 0, so that the stress release layer 109 is (In)_cGa_1-cN/GaN)_nThe period n of the stress release layer 109 is 3, the thickness of the well layer is 18 angstrom, the thickness of the barrier layer is 55 angstrom, and the doping concentration of silicon in the barrier layer is 5.8E17cm^-3。

In the second embodiment, the Al composition b of the barrier layer In the MQW layer 111 takes a value of 0, so that the MQW layer 111 takes an (In) value_aGa_1-aN/GaN)_mThe period structure of (1), wherein the period m is 9, the thickness of the well layer in the multiple quantum well layer 111 is 38 angstrom, the thickness of the barrier layer is 48 angstrom, and the doping concentration of silicon in the barrier layer is 1E16cm^-3. The period n of the stress release layer 109 was 4, the well layer was 10 angstroms thick, the barrier layer was 95 angstroms thick, the Al component b of the barrier layer was 2%, and the doping concentration of silicon in the barrier layer was 2.7E17cm^-3。

In the third embodiment, the Al composition b of the barrier layer In the MQW layer 111 takes a value of 0, so that the MQW layer 111 takes an (In) value_aGa_1-aN/GaN)_mThe period structure of (1), wherein the period m is 9, the thickness of the well layer in the multiple quantum well layer 111 is 35 angstrom, the thickness of the barrier layer is 48 angstrom, and the doping concentration of silicon in the barrier layer is 1E16cm^-3. The value of the Al component b of the barrier layer In the stress release layer 109 is 0, so that the stress release layer 109 is (In)_cGa_1-cN/GaN)_nIn which the stress release layerThe period n of 109 is 20, the thickness of the well layer is 13 angstrom, the thickness of the barrier layer is 18 angstrom, and the doping concentration of silicon in the barrier layer is 2.7E17cm^-3。

In the above 3 specific embodiments, the thin barrier or ultra-thin barrier structure of the stress release layer 109 is combined with the ultra-thin barrier structure of the multiple quantum well layer 110 to regulate and control the stress of the multiple quantum well, the structure of the multiple V-shaped recesses, and the electron hole distribution, so as to improve the radiative recombination efficiency, wherein the thickness of the thin barrier structure is not greater than 100 angstroms, and the thickness of the ultra-thin barrier structure is not greater than 60 angstroms.

Because the stress release layer adopts a thin barrier structure and forms a composite thin barrier structure with the ultrathin barrier structure of the multiple quantum wells, the stress state, the V-shaped depression and the electron hole distribution of the multiple quantum wells are regulated and controlled, and the radiation recombination efficiency is improved; the thickness of the common thick barrier is about 100-200 angstrom, the thickness of the thin barrier is below 100 angstrom, and the thickness of the ultra-thin barrier used in the invention is 40-60 angstrom.

The plurality of V-shaped recesses extend from the surface of the multiple quantum well layer 111 into the first GaN high-carbon doping layer 107 and/or the second GaN high-carbon doping layer 108 and/or the stress relief layer 109.

In some specific embodiments, the V-shaped recess 112a extends from the surface of the multiple quantum well layer 111 into the first GaN high-carbon doping layer 107, the V-shaped recess 112b extends from the surface of the multiple quantum well layer 111 into the second GaN high-carbon doping layer 108, and the V-shaped recess 112c extends from the surface of the multiple quantum well layer 111 into the stress relief layer 109.

On the surface of the multiple quantum well layer 111, the opening size range of the multiple V-shaped recesses comprises 100 to 500 nanometers, and the density range comprises 10⁷To 10⁹cm^-2. In some preferred embodiments, the plurality of V-shaped depressions have an opening size of 250 nm and a density of 10⁸cm^-2。

The electron blocking layer 113 is located on the multiple quantum well layer 111, covering the plurality of V-shaped recesses. The electron blocking layer 113 includes Al_iGa_1-iN/AlN layer not doped with Si or Mg, wherein Al_iGa_1-iThe value range of the Al component i of the N layer comprises 0 to 1, and Al_iGa_1- _iThe thickness of the N layer is in the range of 40 to 80 angstroms, and the thickness of the AlN layerThe range includes 10 to 30 angstroms. In some preferred embodiments, Al_iGa_1-iThe thickness of the N layer was 55 angstroms and the thickness of the AlN layer was 23 angstroms.

The hole injection layer 114 is disposed on the electron blocking layer 113, and the Mg doping concentration of the hole injection layer 114 ranges from 1E19 to 1E21cm^-3A thickness ranging from 100 to 300 angstroms, wherein the material of the hole injection layer 114 comprises Al_jIn_kGa_1-j-kN in Al_jIn_kGa_1-j-kIn N, the value range of the Al component j is 0-60%, and the value range of the In component k is 0-40%. In some preferred embodiments, the hole injection layer 114 has a Mg doping concentration of 1.7E20cm^-3The hole injection layer 114 was 168 angstroms thick.

A hole expansion layer 115 is located on the hole injection layer 114, the hole expansion layer 115 has a thickness ranging from 200 to 600 angstroms, and the material of the hole expansion layer 115 includes undoped GaN, in which the Mg doping concentration is 0. The doping concentration range of Mg in the hole expansion layer 115 after secondary ion mass spectrometry comprises 1E 19-5E 19cm^-3. In some preferred embodiments, hole expansion layer 115 has a thickness of 400 angstroms.

A GaN hole supply layer 116 is disposed on the hole extension layer 115, the GaN hole supply layer 116 having a thickness ranging from 50 to 400 angstroms, and the GaN hole supply layer 116 having a doping concentration of Mg ranging from 1E19 to 5E20cm^-3For supplying holes into the multiple quantum well layer 111. In some preferred embodiments, the thickness of the GaN hole supply layer 116 is 200 angstroms.

A contact layer 117 is on the GaN hole supply layer 116, the contact layer 117 has a thickness ranging from 10 to 50 angstroms, and the Mg doping concentration in the contact layer 117 ranges from 5E19 to 1E21cm^-3. In some preferred embodiments, contact layer 117 is 25 angstroms thick.

The method of an embodiment of the present invention starts with a substrate 100, and an AlN buffer layer 101 is formed on the substrate 100, as shown in fig. 2.

In this step, an AlN single crystal thin film is grown on the substrate 100, for example, using a magnetic chamber sputtering process, wherein the AlN buffer layer 101 has a thickness ranging from 100 to 500 angstroms, preferably 200 angstroms. In the present embodiment, the substrate 100 includes one of a sapphire substrate, a silicon substrate, a SiC substrate, a wet-patterned sapphire substrate (WPSS), and a dry-patterned sapphire substrate (DPSS). In some preferred embodiments, substrate 100 is a Dry Patterned Sapphire Substrate (DPSS).

Further, a GaN buffer layer 102 is formed on the AlN buffer layer 101, as shown in fig. 2. In this step, GaN is deposited on the AlN buffer layer 101, for example, using a Metal-organic Chemical Vapor Deposition (MOCVD) process, wherein the GaN buffer layer 102 has a thickness in a range including 30 to 100 angstroms, preferably 60 angstroms.

In the present embodiment, the AlN buffer layer 101 and the GaN buffer layer 102 form a double buffer structure to release lattice mismatch stress, and specifically, the AlN buffer layer 101 and the GaN buffer layer 102 both include N, so that the AlN buffer layer 101 and the GaN buffer layer 102 have the same element, thereby reducing lattice mismatch between layers and controlling the release of stress. In some preferred embodiments, DPSS is selected for substrate 100, and therefore Al is also included in substrate 100, having the same elements as AlN buffer layer 101, further controlling the release of stress.

Further, an undoped GaN layer 103 is formed on the GaN buffer layer 102, as shown in fig. 2. In this step, the undoped GaN layer 103 is formed on the GaN buffer layer 102, for example, using a two-step growth process of three-dimensional (3D) growth and two-dimensional (2D) growth, thereby controlling the dislocation density range in the undoped GaN layer to 10⁶To 10⁹cm^-2Wherein the thickness of the undoped GaN layer 103 ranges from 3 to 5 μm, preferably 4 μm.

Further, a first GaN electron supply layer 104 is formed on the undoped GaN layer 103, as shown in fig. 2. The thickness range of the first GaN electron supply layer 104 includes 0.5 to 1.5 μm, wherein the doping concentration range of silicon in the first GaN electron supply layer 104 includes 1E18 to 5E18cm^-3The doping concentration range of carbon includes 5E16 to1E17cm^-3. In some preferred embodiments, the thickness of the first GaN electron supply layer 104 is 1 μm, and the doping concentration of silicon in the first GaN electron supply layer 104 is 2.3E18cm^-3The doping concentration of carbon is 6.8E16cm^-3。

Further, a hole blocking layer 105 is formed on the first GaN electron supply layer 104, as shown in fig. 2. The material of the hole blocking layer 105 includes Al_hGa_1-hN, in a thickness range including 20 to 200 angstroms, and a silicon doping concentration range in the hole blocking layer 105 including 1E18 to 2E19cm^-3。

Further, a second GaN electron supply layer 106 is formed on the hole blocking layer 105, as shown in fig. 2. The thickness of the second GaN electron supply layer 106 ranges from 2 μm to 3 μm, wherein the doping concentration of silicon in the second GaN electron supply layer 106 ranges from 1E19 to 8E19cm^-3The doping concentration range of carbon includes 5E16 to 1E17cm^-3. In some preferred embodiments, the doping concentration of silicon in the second GaN electron supply layer 106 is 1.2E19cm^-3The doping concentration of carbon is 6.8E16cm^-3。

Further, a first GaN high-carbon doped layer 107 is formed on the second GaN electron supply layer 106, and a minute V-shaped recess 112a is formed on the first GaN high-carbon doped layer 107, as shown in fig. 3. The doping concentration range of carbon in the first GaN high-carbon doping layer 107 includes 1E17 to 7E17cm^-3The doping concentration range of silicon comprises 1E 18-1E 19cm^-3. In some preferred embodiments, the doping concentration of carbon in the first GaN high-carbon doped layer 107 is 5.3E17cm^-3Doping concentration of silicon is 4.5E18cm^-3。

Further, a second GaN high-carbon doped layer 108 is formed on the first GaN high-carbon doped layer 107, and a minute V-shaped recess 112b is formed on the second GaN high-carbon doped layer 108, and at the same time, since no filling layer grown laterally fills the V-shaped recess 112a, the V-shaped recess 112a extends into the second GaN high-carbon doped layer 108, as shown in fig. 4. Wherein the doping concentration range of carbon in the second GaN high-carbon doping layer 108 comprises 7E 17-5E 18cm^-3The doping concentration range of silicon comprises 1E 18-1E 19cm^-3. In some preferred embodiments, the second GaN is highThe doping concentration of carbon in the carbon doping 108 is 1.1E18cm^-3Doping concentration of silicon is 4.8E18cm^-3。

Further, a stress relief layer 109 is formed on the second GaN highly doped carbon layer 108, and a tiny V-shaped recess 112c is formed on the stress relief layer 109, since there is no laterally grown filling layer to fill the V-shaped

recesses

112a and 112b, and the V-shaped

recesses

112a and 112b extend into the stress relief layer 109, respectively, as shown in fig. 5. The stress release layer 109 includes a plurality of barrier layers and a plurality of well layers stacked alternately. The stress release layer 109 is (In)_cGa_1-cN/Al_dGa_1-dN)_nThe value range of the period n comprises 1 to 30, wherein In_cGa_1-cN layer as well layer not doped with Si, In_cGa_1-cThe thickness range of the N layer comprises 5 to 30 angstroms, the value of the In component c In the IncGa1-cN layer is 0 to 30 percent, c < a, the AldGa1-dN layer is used as a barrier layer, the thickness range of the AldGa1-dN layer comprises 10 to 100 angstroms, and the thickness range of the AldGa1-_dThe value of Al component d in the N layer is 0-20%, Al_dGa_1-dThe doping concentration range of silicon in the N layer comprises 5E 16-5E 18cm^-3。

In the present embodiment, the carbon doping concentrations in the GaN electron supply layer (including the first GaN electron supply layer 104 and the second GaN electron supply layer 106), the first GaN high-carbon doped layer 107, and the second GaN high-carbon doped layer 108 sequentially vary in a gradient manner, and the thickness of the single barrier layer in the stress release layer 109 is less than 100 angstroms, which is a thin barrier structure, and facilitates the release of stress, so that the opening position of the V-shaped recess can be controlled by a dual control means (respectively controlling the gradient variation of the carbon doping concentration and the thickness of the barrier layer).

Through the gradient change of the carbon doping concentration, the V-shaped

depressions

112a, 112b and 112c can be gradually opened through the gradient change of the carbon doping, the higher the carbon doping content is, the higher the opening efficiency of the V-shaped depressions is, but the problem that the crystal quality is poor exists, so that the material quality and the optimum opening efficiency of the V-shaped depressions can be considered by adopting a step-by-step opening mode; and the stress release of the thin barrier is combined, so that the V-shaped recess can be opened through the stress release, and the opening of the V-shaped recess is regulated and controlled through the coordination of the stress release and the stress release.

Further, a transition layer 110 is formed on the stress relieving layer 109, and V-shaped

recesses

112a, 112b and 112c are controlled to extend into the transition layer 110, respectively, as shown in fig. 6. Wherein the transition layer 110 comprises Al_eGa_1-eN/In_fGa_1-fN/Al_gGa_1-gN layer of Al_eGa_1-eIn the N layer, the value range of the Al component e is 0 to 1 In_fGa_1-fIn the N layer, the value of the In component f is In the range of 0 to 1 In Al_gGa_1-gIn the N layer, the value range of the Al component g comprises 0 to 1, and Al_eGa_1-eN layer, In_fGa_1-fN layer and Al_gGa_1-gThe N layers each have a thickness in the range of 20 to 80 angstroms and the transition layer 110 has a silicon doping concentration in the range of 1E17 to 1E19cm^-3。

Further, a multiple quantum well layer 111 is formed on the transition layer 110, and the V-shaped

recesses

112a, 112b, and 112c are controlled to continue to extend into the multiple quantum well layer 111 to the surface of the quantum well layer 111, respectively, as shown in fig. 7. The mqw layer 111 includes a plurality of barrier layers and a plurality of well layers stacked alternately. The multiple quantum well layer 111 is (In)_aGa_1-aN/Al_bGa_1-bN)_mThe value range of the period m is from 5 to 15, the range of the light-emitting wavelength lambda is from 420 to 520 nanometers, wherein In_aGa_1-aN layer as well layer not doped with Si, In_aGa_1-aThe thickness of the N layer ranges from 30 to 40 angstroms In_aGa_1-aIn the N layer, the value range of the In component a comprises 10 to 30 percent; al (Al)_bGa_1-bN layer as barrier layer, Al_bGa_1-bThe thickness of the N layer is in the range of 40 to 60 angstroms, in Al_bGa_1-bIn the N layer, the value range of the Al component b comprises 0 to 20 percent, and Al_bGa_1-bThe doping concentration range of silicon in the N layer comprises 1E 15-1E 17cm^-3。

In this embodiment, since the barrier layer thickness in the multiple quantum well layer 111 is less than 60 angstroms, the barrier layer structure is an ultra-thin barrier layer structure, which is beneficial to reducing the lattice mismatch stress of the well barrier and reducing the multiple quantumThe quantum in the well layer 111 limits the Stark effect, and the electron-hole recombination efficiency of the multiple quantum well is improved. The ultra-thin barrier layer structure in the multiple quantum well layer 111 and the thin barrier structure in the stress release layer 109 form a composite thin barrier structure, the composite thin barrier structure is used for regulating and controlling the stress state of the multiple quantum well, the structure of the V-shaped recess and the electron hole distribution, so that the radiation recombination efficiency is improved, specifically, the transition layer 110 can be combined, the release of stress is regulated by regulating the Al component in the composite thin barrier structure, and further the size change of a plurality of V-shaped recesses is regulated and controlled, wherein the opening size range of the V-shaped recesses on the surface of the multiple quantum well layer 111 comprises 100 to 500 nanometers, preferably 250 nanometers, and the density range of the plurality of V-shaped recesses comprises 10 nanometers⁷To 10⁹cm^-2。

In the embodiment, the stress between InGaN and GaN is controlled by the composite thin barrier structure, so that the stress mismatch is reduced, and the quantum confinement Stark QCSE effect is reduced.

In the third embodiment, the Al composition b of the barrier layer In the MQW layer 111 takes a value of 0, so that the MQW layer 111 takes an (In) value_aGa_1-aN/GaN)_mThe period structure of (1), wherein the period m is 9, the thickness of the well layer in the multiple quantum well layer 111 is 35 angstrom, the thickness of the barrier layer is 48 angstrom, and the doping concentration of silicon in the barrier layer is 1E16cm^-3. The value of the Al component b of the barrier layer In the stress release layer 109 is 0, so that the stress release layer 109 is (In)_cGa_1-cN/GaN)_nThe period n of the stress release layer 109 is 20, the thickness of the well layer is 13 angstrom, the thickness of the barrier layer is 18 angstrom, and the doping concentration of silicon in the barrier layer is 2.7E17cm^-3。

Further, an electron blocking layer 113 is formed on the multiple quantum well layer 111 covering the multiple V-shaped recesses, as shown in fig. 8. The electron blocking layer 113 includes Al_iGa_1-iN/AlN layer not doped with Si or Mg, wherein Al_iGa_1-iThe value range of the Al component i of the N layer comprises 0 to 1, and Al_iGa_1-iThe N layer thickness range includes 40 to 80 angstroms and the AlN layer thickness range includes 10 to 30 angstroms. In some preferred embodiments, Al_iGa_1-iThe thickness of the N layer was 55 angstroms and the thickness of the AlN layer was 23 angstroms.

Further, a hole injection layer 114, a hole expansion layer 115, a GaN hole supply layer 116, and a contact layer 117 are sequentially formed on the electron blocking layer 113, thereby forming an epitaxial structure as shown in fig. 1.

The Mg doping concentration range of the hole injection layer 114 includes 1E19 to 1E21cm^-3And a thickness ranging from 100 to 300 angstroms, wherein the hole injection layer comprises Al_jIn_kGa_1-j-kN in Al_jIn_kGa_1-j-kIn N, the value range of the Al component j is 0-60%, and the value range of the In component k is 0-40%. In some preferred embodiments, the hole injection layer 114 has a Mg doping concentration of 1.7E20cm^-3The hole injection layer 114 was 168 angstroms thick.

The thickness of hole spreading layer 115 may range from 200 to 600 angstroms, and the material of hole spreading layer 115 may include undoped materialWherein the Mg doping concentration is 0. The doping concentration range of Mg in the hole expansion layer after secondary ion mass spectrometry comprises 1E 19-5E 19cm^-3. In some preferred embodiments, hole expansion layer 115 has a thickness of 400 angstroms.

The thickness of the GaN hole supply layer 116 ranges from 50 to 400 angstroms, and the doping concentration of Mg in the GaN hole supply layer 116 ranges from 1E19 to 5E20cm^-3For supplying holes into the multiple quantum well layer 111. In some preferred embodiments, the thickness of the GaN hole supply layer 116 is 200 angstroms.

The thickness of contact layer 117 ranges from 10 to 50 angstroms, and the doping concentration of Mg in contact layer 117 ranges from 5E19 to 1E21cm^-3. In some preferred embodiments, contact layer 117 is 25 angstroms thick.

Further, a stress release layer is formed between the GaN electron supply layer and the multiple quantum well layer, the stress release layer comprises a plurality of barrier layers and a plurality of well layers which are stacked alternately, a thin barrier structure is formed by controlling the thickness of the barrier layers in the stress release layer to be below 100 angstroms, lattice mismatch stress of a well barrier in the stress release layer is reduced, meanwhile, the barrier layers in the stress release layer and the barrier layers in the multiple quantum well layer form a composite thin barrier structure, and the composite thin barrier structure is used for regulating and controlling the stress state of the multiple quantum well, the structure of the V-shaped recess and electron hole distribution, so that the radiation recombination efficiency is improved.

Further, the stress state of the multiple quantum well is regulated and controlled in the following way: 1. the multiple quantum well layer is formed by an ultrathin barrier with the thickness of 40-60 angstrom meters, the stress release layer is formed by a double-thin-barrier structure with the thickness of 10-100 angstrom meters, the size of a V-shaped recess is controlled, the quantum confinement Stark QCSE effect is reduced by controlling stress through the thin barrier, and the recombination efficiency of electron holes is improved; 2. the opening and the density of the V-shaped recess are controlled by the carbon doping content by adopting a high-carbon doping gradient layer (a first high-carbon doping layer and a second carbon doping layer or a combination of a plurality of carbon doping layers); the carbon doping of this patent adopts gradient gradual change mode, compromises opening that crystal quality and V type are sunken.

In the above description, the technical details of patterning, etching, and the like of each layer are not described in detail. It will be appreciated by those skilled in the art that layers, regions, etc. of the desired shape may be formed by various technical means. In addition, in order to form the same structure, those skilled in the art can also design a method which is not exactly the same as the method described above. In addition, although the embodiments are described separately above, this does not mean that the measures in the embodiments cannot be used in advantageous combination.

The embodiments of the present invention have been described above. However, these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. The scope of the invention is defined by the appended claims and equivalents thereof. Various alternatives and modifications can be devised by those skilled in the art without departing from the scope of the invention, and these alternatives and modifications are intended to fall within the scope of the invention.

Claims

1. An epitaxial structure, comprising:

a GaN electron supply layer over the substrate;

a first GaN high-carbon doped layer located above the GaN electron supply layer;

the second GaN high-carbon doping layer is positioned on the first GaN high-carbon doping layer;

the multi-quantum well layer is positioned above the second GaN high-carbon doping layer and comprises a plurality of barrier layers and a plurality of well layers which are alternately stacked;

a GaN hole supply layer located above the multiple quantum well layer; and

a plurality of V-shaped recesses extending from a surface of the multiple quantum well layer toward the substrate,

the GaN electron supply layer, the first GaN high-carbon doping layer and the second GaN high-carbon doping layer are sequentially subjected to incremental gradient change in carbon doping concentration, so that the plurality of V-shaped depressions are controlled to be sequentially opened in the first GaN high-carbon doping layer and the second GaN high-carbon doping layer.

2. The epitaxial structure of claim 1 wherein each barrier layer in the multiple quantum well layer has a thickness of no more than 60 angstroms.

3. The epitaxial structure of claim 2, further comprising:

the stress release layer is positioned between the GaN electron supply layer and the multi-quantum well layer and comprises a plurality of barrier layers and a plurality of well layers which are alternately stacked;

and the barrier layer in the stress release layer and the barrier layer in the multi-quantum well layer form a composite thin barrier structure.

4. The epitaxial structure of claim 3, wherein each barrier layer in the stress relief layer has a thickness no greater than 100 angstroms.

5. The epitaxial structure of claim 3 wherein the composite thin barrier structure regulates the stress state of the MQW layer, the structure of the V-shaped recess, and the distribution of electrons and holes.

6. The epitaxial structure of claim 1 wherein the multiple quantum well layer is (In)_aGa_1-aN/Al_bGa_1- _bN)_mThe value range of the period m includes 5 to 15,

wherein, In_aGa_1-aN layer as well layer, the In_aGa_1-aOf N layersA thickness In the range of 30 to 40 angstroms, In_aGa_1-aIn the N layer, the value range of the In component a comprises 10 to 30 percent;

Al_bGa_1-bn layer as barrier layer, the Al layer_bGa_1-bThe thickness of the N layer is in the range of 40 to 60 angstroms, in said Al_bGa_1-bIn the N layer, the value range of the Al component b comprises 0 to 20 percent, and the Al_bGa_1-bThe doping concentration range of silicon in the N layer comprises 1E 15-1E 17cm^-3。

7. The epitaxial structure of claim 3, wherein the stress relief layer is (In)_cGa_1-cN/Al_dGa_1- _dN)_nThe value range of the period n comprises 1 to 30, and In_cGa_1-cThe value of the In component c In the N layer is 0-30%, and c is less than a;

wherein, In_cGa_1-cN layer as well layer, the In_cGa_1-cThe thickness of the N layer ranges from 5 to 30 angstroms,

Al_dGa_1-dn layer as barrier layer, the Al layer_dGa_1-dThe thickness of the N layer is in the range of 10 to 100 angstroms, and the Al layer_dGa_1-dThe value of the Al component d in the N layer is 0 to 20 percent, and the Al component d is_dGa_1-dThe doping concentration range of silicon in the N layer comprises 5E 16-5E 18cm^-3。

8. The epitaxial structure of claim 4, further comprising a transition layer between the MQW layer and the stress relief layer for adjusting the opening size of the V-shaped recess in cooperation with the composite thin barrier structure.

9. The epitaxial structure of claim 8, wherein the transition layer comprises Al_eGa_1-eN/In_fGa_1-fN/Al_gGa_1-gN layers are formed on the surface of the substrate,

in Al_eGa_1-eIn the N layer, the value range of the Al component e is 0 to 1 In_fGa_1-fIn the N layer, the value of the In component f is In the range of 0 to 1 In Al_gGa_1-gIn the N layer, the value range of the Al component g comprises 0 to 1,

the Al is_eGa_1-eN layer, said In_fGa_1-fN layer and the Al_gGa_1-gThe N layers each have a thickness in the range of 20 to 80 angstroms,

the doping concentration range of silicon in the transition layer comprises 1E 17-1E 19cm^-3。

10. The epitaxial structure of claim 3 wherein the plurality of V-shaped recesses have an opening size in a range from 100 to 500 nanometers at the surface of the MQW layer.

11. The epitaxial structure of claim 1, wherein the doping concentration range of carbon in the GaN electron supply layer comprises 5E16 to 1E17cm^-3The doping concentration range of carbon in the first GaN high-carbon doping layer comprises 1E 17-7E 17cm^-3The doping concentration range of carbon in the second GaN high-carbon doping layer comprises 7E 17-5E 18cm^-3。

12. The epitaxial structure of claim 1, wherein the doping concentration ranges of silicon in the first GaN high-carbon doped layer and the second GaN high-carbon doped layer each include 1E 18-1E 19cm^-3。

13. The epitaxial structure of claim 3, wherein the plurality of V-shaped recesses extend from the MQW layer surface into the first GaN high-carbon doped layer and/or the second GaN high-carbon doped layer and/or the stress relief layer.

14. The epitaxial structure of claim 13, further comprising:

an AlN buffer layer on the substrate;

a GaN buffer layer on the AlN buffer layer; and

an undoped GaN layer between the GaN electron supply layer and the GaN buffer layer,

the AlN buffer layer and the GaN buffer layer form a double buffer layer structure for releasing lattice mismatch stress between the substrate and the non-doped GaN layer.

15. The epitaxial structure of claim 14, wherein the AlN buffer layer has a thickness in a range including 100 to 500 angstroms, the GaN buffer layer has a thickness in a range including 30 to 100 angstroms,

wherein the AlN buffer layer is a single crystal thin film layer.

16. The epitaxial structure of claim 14, wherein the thickness of the undoped GaN layer ranges from 3 to 5 μm, and is formed using three-dimensional growth and two-dimensional growth methods to control the dislocation density in the undoped GaN layer to 10⁶To 10⁹cm^-2Within.

17. The epitaxial structure of claim 16 wherein the density profile of the plurality of V-shaped recesses at the surface of the mqw layer comprises 10⁷To 10⁹cm^-2。

18. The epitaxial structure of claim 14, wherein the GaN electron supply layer comprises:

a first GaN electron supply layer on the undoped GaN; and

a second GaN electron supply layer located above the first GaN electron supply layer,

wherein the thickness of the first GaN electron supply layer ranges from 0.5 μm to 1.5 μm, and the doping concentration of silicon in the first GaN electron supply layer ranges from 1E18 to 5E18cm^-3The second GaN electron supply layer has a thickness in a range of 2 to 3 μm, and the second GaN electron supply layerThe doping concentration range of silicon in the supply layer comprises 1E 19-8E 19cm^-3。

19. The epitaxial structure of claim 18, further comprising a hole blocking layer between the first GaN electron supply layer and the second GaN electron supply layer,

the material of the hole blocking layer comprises Al_hGa_1-hN, thickness ranging from 20 to 200 angstroms, and silicon doping concentration in the hole blocking layer ranging from 1E18 to 2E19cm^-3Wherein the value range of h comprises 0 to 1.

20. The epitaxial structure of claim 19, further comprising:

the electron barrier layer is positioned on the multi-quantum well layer;

a hole injection layer on the electron blocking layer;

a hole-expanding layer between the hole-injecting layer and the GaN hole-supplying layer; and

a contact layer on the GaN hole supply layer.

21. The epitaxial structure of claim 20, wherein the electron blocking layer comprises Al_iGa_1-iAn N/AlN layer formed on the substrate,

wherein, Al_iGa_1-iThe value range of the Al component i in the N layer comprises 0 to 1, wherein Al is_iGa_1-iThe N layer thickness range includes 40 to 80 angstroms,

the AlN layer has a thickness in a range including 10 to 30 angstroms.

22. The epitaxial structure of claim 20, wherein the doping concentration range of Mg in the hole injection layer comprises 1E19 to 1E21cm^-3A thickness in a range including 100 to 300 angstroms,

wherein the hole injection layer comprises Al_jIn_kGa_1-j-kA N layer of Al_jIn_kGa_1-j-kIn the N layer, the value range of the Al component j is 0-60%, and the value range of the In component k is 0-40%.

23. The epitaxial structure of claim 20, wherein the hole expansion layer has a thickness in a range including 200 to 600 angstroms, the hole expansion layer includes a GaN layer,

wherein, after secondary ion mass spectrometry, the doping concentration range of Mg in the hole expansion layer comprises 1E 19-5E 19cm^-3。

24. The epitaxial structure of claim 20, wherein the GaN hole supply layer has a thickness in the range of 50 to 400 angstroms and a Mg doping concentration in the GaN hole supply layer in the range of 1E19 to 5E20cm^-3。

25. The epitaxial structure of claim 20, wherein the contact layer has a thickness in the range of 10 to 50 angstroms and the Mg doping concentration in the contact layer is in the range of 5E19 to 1E21cm^-3。

26. The epitaxial structure of any of claims 20 to 25, wherein the plurality of V-shaped recesses are filled in sequence with the electron blocking layer, the hole injection layer, the hole expansion layer and the GaN hole supply layer.

27. A method of fabricating an epitaxial structure, comprising:

forming a GaN electron supply layer over a substrate;

forming a first GaN high-carbon doped layer over the GaN electron supply layer;

forming a second GaN high-carbon doping layer on the first GaN high-carbon doping layer;

forming a multi-quantum well layer including a plurality of barrier layers and a plurality of well layers alternately stacked above the second GaN high-carbon doping layer;

forming a GaN hole supply layer over the multiple quantum well layer; and

forming a plurality of V-shaped recesses extending from a surface of the multiple quantum well layer toward the substrate direction,

28. The method of claim 27 wherein each barrier layer in the multiple quantum well layer has a thickness of no more than 60 angstroms.

29. The method of manufacturing of claim 28, further comprising:

forming a stress release layer including a plurality of barrier layers and a plurality of well layers alternately stacked between the GaN electron supply layer and the multi-quantum well layer;

30. The method of manufacturing of claim 29, wherein each barrier layer in the stress relieving layer has a thickness of no more than 100 angstroms.

31. The method of claim 30, wherein the composite thin barrier structure is used to control the stress state of the MQW layer, the structure of the V-shaped recess, and the distribution of electrons and holes.

32. The manufacturing method according to claim 29, wherein the multiple quantum well layer is (In)_aGa_1-aN/Al_bGa_1-bN)_mThe value range of the period m includes 5 to 15,

wherein, In_aGa_1-aThe N layer is used as a well layerIn_aGa_1-aThe thickness of the N layer ranges from 30 to 40 angstroms inclusive, In_aGa_1-aIn the N layer, the value range of the In component a comprises 10 to 30 percent;

33. The method of manufacturing of claim 32, wherein the stress relief layer is (In)_cGa_1-cN/Al_dGa_1-dN)_nThe value of the period n of the superlattice periodic structure is in a range from 1 to 30,

wherein, In_cGa_1-cN layer as well layer, the In_cGa_1-cThe thickness of the N layer is In the range of 5 to 30 angstroms, and the In is_cGa_1-cThe value of the In component c In the N layer is 0-30%, and c is less than a;

34. The method according to claim 29, further comprising forming a transition layer between the MQW layer and the stress relieving layer for adjusting an opening size of the V-shaped recess in cooperation with the composite thin barrier structure,

the opening size of the V-shaped recess is regulated and controlled by regulating and controlling the thickness of the multiple quantum well layer and the barrier layer in the stress release layer, Al components and forming conditions respectively.

35. According toThe method of manufacturing of claim 34, wherein the transition layer comprises Al_eGa_1-eN/In_fGa_1- _fN/Al_gGa_1-gN layers are formed on the surface of the substrate,

36. The method of manufacturing of claim 35, wherein the plurality of V-shaped depressions have an opening size ranging from 100 to 500 nanometers.

37. The method of claim 27, wherein the GaN electron supply layer has a carbon doping concentration in a range from 5E16 to 1E17cm^-3The doping concentration range of carbon in the first GaN high-carbon doping layer comprises 1E 17-7E 17cm^-3The doping concentration range of carbon in the second GaN high-carbon doping layer comprises 7E 17-5E 18cm^-3。

38. The method of claim 27, wherein the doping concentration ranges of Si in the first GaN high-carbon doped layer and the second GaN high-carbon doped layer each include 1E 18-1E 19cm^-3。

39. The method according to claim 29, wherein the plurality of V-shaped recesses extend from the MQW layer surface into the first GaN high-carbon doped layer and/or the second GaN high-carbon doped layer and/or the stress relief layer.

40. The method of manufacturing of claim 39, further comprising:

forming an AlN buffer layer on the substrate;

forming a GaN buffer layer on the AlN buffer layer; and

forming an undoped GaN layer between the GaN electron supply layer and the GaN buffer layer,

41. The manufacturing method according to claim 40, wherein the step of forming the AlN buffer layer comprises growing an AlN single-crystal thin film on the substrate by a magnetic chamber sputtering method, and a thickness of the AlN buffer layer is in a range of 100 to 500 angstroms.

42. The method of manufacturing according to claim 41, wherein the step of forming the GaN buffer layer includes depositing a GaN material on the AlN buffer layer using a metal organic chemical vapor deposition method, the GaN buffer layer having a thickness in a range including 30 to 100 angstroms.

43. The method of claim 40, wherein the step of forming the undoped GaN layer comprises forming the undoped GaN layer on the GaN buffer layer by a two-step growth method of three-dimensional growth and two-dimensional growth to control the dislocation linear density in the undoped GaN layer to be within a range of 10⁶To 10⁹cm^-2In the above-mentioned manner,

wherein a thickness of the undoped GaN layer ranges from 3 to 5 μm.

44. The manufacturing method according to claim 43, wherein a density distribution range of the plurality of V-shaped recesses at the surface of the MQW layer includes 10⁷To 10⁹cm^-2。

45. The manufacturing method according to claim 40, wherein the step of forming the GaN electron supply layer includes:

forming a first GaN electron supply layer on the undoped GaN; and

forming a second GaN electron supply layer over the first GaN electron supply layer,

wherein the thickness of the first GaN electron supply layer ranges from 0.5 μm to 1.5 μm, and the doping concentration of silicon in the first GaN electron supply layer ranges from 1E18 to 5E18cm^-3A thickness range of the second GaN electron supply layer includes 2 to 3 μm, and a Si doping concentration range in the second GaN electron supply layer includes 1E19 to 8E19cm^-3。

46. The method of manufacturing according to claim 45, further comprising forming a hole blocking layer between the first GaN electron supply layer and the second GaN electron supply layer,

47. The method of manufacturing of claim 46, further comprising;

forming an electron blocking layer on the multi-quantum well layer;

forming a hole injection layer on the electron blocking layer;

forming a hole expansion layer between the hole injection layer and the GaN hole supply layer; and

a contact layer is formed on the GaN hole supply layer.

48. The method of manufacturing of claim 47, wherein the electron blocking layer comprises Al_iGa_1-iAn N/AlN layer formed on the substrate,

the AlN layer has a thickness in a range including 10 to 30 angstroms.

49. The method of claim 47, wherein the doping concentration range of Mg in the hole injection layer comprises 1E 19-1E 21cm^-3A thickness in a range including 100 to 300 angstroms,

50. The method of manufacturing according to claim 47, wherein the hole expanding layer has a thickness ranging from 200 to 600 angstroms, the hole expanding layer includes a GaN layer,

51. The method of claim 47, wherein the GaN hole supply layer has a thickness ranging from 50 to 400 angstroms, and the doping concentration of Mg in the GaN hole supply layer ranges from 1E19 to 5E20cm^-3。

52. The method of claim 47, wherein the contact layer has a thickness ranging from 10 to 50 angstroms and the Mg doping concentration in the contact layer ranges from 5E19 to 1E21cm^-3。

53. The production method according to any one of claims 47 to 52, wherein the plurality of V-shaped recesses are filled with the electron blocking layer, the hole injection layer, the hole expansion layer, and the GaN hole supply layer in this order.