阅读说明：本技术 一种在m面氮化镓基板上生长蓝色发光二极管的外延方法 (Epitaxial method for growing blue light-emitting diode on m-plane gallium nitride substrate ) 是由 刘园旭 于 2020-05-09 设计创作，主要内容包括：本发明公开了一种在m面氮化镓基板上生长蓝色发光二极管的外延方法,涉及半导体外延层生长技术领域,包括在m面GaN基板顶部利用金属有机化学气相沉积方法生长一层非掺杂氮化镓同质外延薄膜浸润层,然后利用金属有机化学气相沉积法自下而上的依次生成N型导电GaN外延层、GaN应力调控层、GaN/InGaN超晶格电子储存层、InGaN/GaN多量子阱发光外延层和复合P型GaN层；本发明实现了m面同质外延获得平整的表面,而且实现了InGaN层In的有效并入实现蓝光量子阱激发。(The invention discloses an epitaxial method for growing a blue light-emitting diode on an m-plane gallium nitride substrate, which relates to the technical field of growth of semiconductor epitaxial layers and comprises the steps of growing a non-doped gallium nitride homoepitaxial thin film infiltration layer on the top of the m-plane GaN substrate by utilizing a metal organic chemical vapor deposition method, and then sequentially generating an N-type conductive GaN epitaxial layer, a GaN stress control layer, a GaN/InGaN superlattice electronic storage layer, an InGaN/GaN multi-quantum well light-emitting epitaxial layer and a composite P-type GaN layer from bottom to top by utilizing the metal organic chemical vapor deposition method; the invention realizes that m-plane homoepitaxy obtains a flat surface, and realizes effective incorporation of InGaN layer In to realize blue light quantum well excitation.)

1. An epitaxial method for growing a blue light emitting diode on an m-plane gallium nitride substrate, comprising the steps of:

s1, providing an m-plane GaN substrate;

s2, growing a layer of non-doped GaN homoepitaxial film wetting layer on the top of the substrate obtained in the step S1 by a metal organic chemical vapor deposition method;

s3, growing an N-type conductive GaN epitaxial layer on the product obtained in the S2 at a high temperature by using a metal organic chemical vapor deposition method;

s4, growing a gallium nitride stress control layer on the product obtained in the S3 by using a metal organic chemical vapor deposition method;

s5, growing a GaN/InGaN superlattice electron storage layer on the product obtained in the S4 by using a metal organic chemical vapor deposition method;

s6, growing an InGaN/GaN multi-quantum well light-emitting epitaxial layer on the product obtained in the S5 by a metal organic chemical vapor deposition method;

and S7, growing a composite P-type GaN layer on the product obtained in the S6 by using a metal organic chemical vapor deposition method.

2. The epitaxial method for growing blue light emitting diodes on m-plane gallium nitride substrates of claim 1, further comprising, between S1 and S2, the steps of:

s1.1, putting the m-plane GaN substrate into metal organic chemical vapor deposition equipment;

s1.2, in the case of m-plane GaN substrate, N₂/NH₃Slowly raising the temperature to 950 ℃ under the atmosphere, and N₂/NH₃The total gas flow is controlled at 120-150slm/min, wherein NH₃The volume accounts for 40-50%, the pressure of the reaction chamber is 75torr, and the heating rate is 60-80 ℃/min;

s1.3, keeping the temperature of 950 ℃ and the pressure of a reaction chamber at 75torr, and reducing N₂Introducing the amount of H to start₂Control N₂:H₂:NH₃The ratio is 25: 25: 50, total gas flow 120 slm/min was constant for 30S, and then the process proceeds to step S2.

3. The epitaxial method for growing blue light emitting diodes on m-plane gallium nitride substrates according to claim 2, wherein step S2 is specifically: and (3) introducing TMGa to provide a Ga source after S1.3 is finished, and starting to grow the undoped gallium nitride homoepitaxial thin film infiltration layer, wherein the growth rate is controlled to be 15-20nm/min, and the growth thickness is 200 nm.

4. The method of claim 3, wherein the blue light emitting diode is grown on an m-plane gallium nitride substrateThe method is characterized in that the temperature is raised to 1000 ℃ within 2min after the step S3, specifically S2 is finished, and the pressure of a reaction chamber is kept at 75torr, N₂:H₂:NH₃The ratio is 25: 25: 50, the total gas flow is unchanged at 120-150slm/min, an N-type conductive GaN epitaxial layer is grown, TMGa is introduced, and SiH is introduced₄As N-type dopant, the growth rate is 30-40um/min, the growth thickness is 1000nm, and the Si doping concentration is 3-5E 18cm^-3The temperature was reduced to 850 ℃ in four minutes, the pressure in the reaction chamber was increased to 200torr, and the introduction of H was stopped₂Hold N₂:NH₃The ratio was 50:50, total gas flow 120-.

5. The epitaxial method of claim 4, wherein S4 is a stress control layer of GaN that starts to grow after S3 is finished, and TMGa and SiH are introduced₄The growth rate is 10-12nm/min, the growth thickness is 100-120nm, the Si doping concentration is 1-3E17cm^-3。

6. The epitaxial method for growing blue light emitting diodes on m-plane gallium nitride substrates of claim 5, wherein S5 is specific to growing GaN/InGaN superlattice electron storage layer after S4 is finished, the layer is of 3 periods GaN/InGaN superlattice structure, and the thickness of a single period is 11 nm; wherein the thickness of the GaN layer is 10nm, and the growth temperature is 870 ℃; the growth temperature of the InGaN layer with the thickness of 1nm is 820 ℃, the Ga source is improved by using the triethyl gallium TEGa, and the In source is provided by the trimethyl indium TMIn.

7. The epitaxial method for growing blue light emitting diode on M-plane GaN substrate according to claim 6, wherein S6 is specifically the InGaN/GaN multiple quantum well light emitting epitaxial layer grown after S5 is finished, the layer is of 6 period InGaN/GaN periodic structure, the thickness of single period is 20nm, the Ga source is increased by using TEGa, and the In source is provided by TMIn; in which the InGaN well layer is 3nm thick, using N₂/NH₃Atmosphere, total gas flow 120-; wherein the GaN potential isThe barrier layer has a thickness of 17nm, comprises three parts, namely a layer of Cap1 before the well layer grows to have a thickness of 1nm and a layer of Cap2 after the well layer grows to have a thickness of 3nm, the growth conditions of the Cap1 layer and the Cap2 layer are completely the same as the well layer conditions except that a TMIn source is not introduced, and the thickness of the other barrier layer is 13nm, and the barrier layer is introduced with H for processing the In segregation growth₂By using N₂:H₂:NH₃The ratio of 4:1:5, the total gas flow rate is not changed at 120-150slm/min, the growth temperature is 870 ℃, SiH4 is adopted for doping, and the concentration is 1E18cm^-3。

8. The epitaxial method for growing blue light emitting diodes on m-plane GaN substrates of claim 7, wherein S7 is a composite P-type GaN layer grown after S6 is finished, the growth pressure is 200torr, N₂:H₂:NH₃The ratio is 2:4:4, the total gas flow is kept at 120-150slm/min and is kept consistent; the composite PGaN layer consists of three parts, namely a low-temperature LT-PGaN layer, a high-temperature HT-PGaN layer and a PP layer in sequence; wherein the LT-PGaN layer has a temperature of 750 ℃, TEGa and Cp2Mg are used for providing Ga and Mg sources, the thickness is 30nm, and the Mg doping concentration is 1E19cm^-3(ii) a Wherein the HT-PGaN layer is grown at 960 deg.C to 60nm with Ga and Mg source and LT-PGaN, and Mg doping concentration is 5E19cm^-3(ii) a Wherein the growth temperature of the PP layer is 900 ℃, Ga and Mg sources are used as LT-PGaN, the growth thickness is 3nm, and the Mg doping concentration is 1E20cm^-3。

9. The epitaxial method of claim 8, wherein the temperature is reduced to 750 ℃ after S7 is finished, and H is turned off₂And NH₃Into pure N₂Environment, N₂Carrying out in-situ annealing for 5min at the flow rate of 130 slm/min; and (5) cooling after the annealing is finished, and finishing the growth.

Technical Field

The invention relates to the technical field of growth of semiconductor epitaxial layers, in particular to an epitaxial method for growing a blue light-emitting diode on an m-plane gallium nitride substrate.

Background

Gallium nitride (GaN) as the third generation semiconductor material has the advantages of direct band gap, large forbidden bandwidth, strong breakdown field, high electron drift saturation velocity, high thermal conductivity, small dielectric constant, high hardness, stable chemical properties, radiation resistance, high temperature resistance and the like. The method has huge application potential and wide market in the fields of blue, green and purple light emitting diodes, laser diodes, ultraviolet detectors, anti-radiation, high-frequency, high-temperature, high-voltage and other electronic devices. At present, a GaN film is mainly a film of a GaN (0001) plane (c plane) grown on a sapphire substrate or a silicon carbide substrate along a polar axis c direction, and a built-in electric field exists in a gallium nitride material due to c-direction spontaneous polarization and piezoelectric polarization. The energy band of the multiple quantum wells can be inclined due to the existence of the built-in electric field, electrons and holes are respectively limited in the triangular potential well at the heterojunction interface, so that the obvious efficiency attenuation Droop effect of devices such as a light emitting diode, a laser diode and an ultraviolet detection device can be caused, and the problem of blue shift of the wavelength can be caused along with the increase of the injection current. For the GaN film growing along the m-plane (1-100) of the non-polar axis direction, because the polarization field is perpendicular to the growth direction, the polarization field influence does not exist on the surface of the material, so the gallium nitride film growing on the m-plane of the non-polar axis has better luminous efficiency maintaining capability in the application of light-emitting diodes and laser diodes theoretically. However, because the m-plane GaN has an in-plane asymmetric structure, it is very easy to grow high-density four-sided pyramidal protrusions on the surface by performing homoepitaxy using Metal Organic Chemical Vapor Deposition (MOCVD), and thus it is not possible to obtain an atomically smooth surface for growing the light-emitting quantum well. Firstly, because an M-plane gallium nitride substrate is difficult to obtain, thanks to the self-power and the like [ "M-plane nonpolar GaN material MOCVD growth and characteristics" [ semiconductor science report, 2007.28.249-252] the growth research of the M-plane GaN in metal organic chemical vapor deposition equipment is specially carried out by using lithium aluminate (LiAlO2) as a substrate, but the growth result of the blue light-emitting diode is not reported. In 2015, clever and the like [ influence of different V/III group elements on performance of an m-plane GaN film ] are used for researching the m-plane GaN film on a sapphire substrate by a Molecular Beam Epitaxy (MBE) method. In 2016, the study of surface adsorption of m-plane GaN film grown by MOVPE, conducted by the artificial crystal institute, 2016.45(8)2022-2033, is still conducted by theoretical calculation to analyze how the optimized epitaxial growth can be conducted on the m-plane GaN film so as to obtain a higher-quality m-plane GaN epitaxial film. In addition, because GaN In the M surface is In an electrodeless state, In is difficult to incorporate when an InGaN light-emitting well grows, so that an InGaN material with a high In component is difficult to obtain, and the light-emitting wavelength is short. In the study of m-plane InGaN/GaN light-emitting diodes, Journal of crystal Growth 313(2010) 1-7, only 405nm light excitation is realized by using 5 periods of 9 nm InGaN quantum wells and 9 nm GaN quantum barriers.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides an epitaxial method for growing a blue light-emitting diode on an M-surface gallium nitride substrate, so as to solve the technical problems that In the prior art, a GaN film is grown on the M-surface GaN substrate and InGaN quantum wells are difficult to incorporate In.

The invention is realized by the following technical scheme:

an epitaxial method for growing a blue light emitting diode on an m-plane gallium nitride substrate, the method comprising the steps of:

s1, providing an m-plane GaN substrate;

s2, growing a layer of non-doped GaN homoepitaxial film wetting layer on the top of the substrate obtained in the step S1 by a metal organic chemical vapor deposition method;

s3, growing an N-type conductive GaN epitaxial layer on the product obtained in the S2 at a high temperature by using a metal organic chemical vapor deposition method;

s4, growing a GaN stress control layer on the product obtained in the S3 by using a metal organic chemical vapor deposition method;

s5, growing a GaN/InGaN superlattice electron storage layer on the product obtained in the S4 by using a metal organic chemical vapor deposition method;

s6, growing an InGaN/GaN multi-quantum well light-emitting epitaxial layer on the product obtained in the S5 by a metal organic chemical vapor deposition method;

and S7, growing a composite P-type GaN layer on the product obtained in the S6 by using a metal organic chemical vapor deposition method.

Further, the method between S1 and S2 further comprises the steps of:

s1.1, putting the m-plane GaN substrate into metal organic chemical vapor deposition equipment;

s1.2, in the case of m-plane GaN substrate, N₂/NH₃Slowly raising the temperature to 950 ℃ under the atmosphere, and N₂/NH₃The total gas flow is controlled at 120-150slm/min, wherein NH₃The volume accounts for 40-50%, the pressure of the reaction chamber is 75torr, and the heating rate is 60-80 ℃/min;

s1.3, keeping the temperature of 950 ℃ and the pressure of a reaction chamber at 75torr, and reducing N₂Introducing the amount of H to start₂Control N₂:H₂:NH₃The ratio is 25: 25: 50, total gas flow 120 slm/min was constant for 30S, and then the process proceeds to step S2.

Further, step S2 specifically includes: and (3) introducing TMGa to provide a Ga source after S1.3 is finished, and starting to grow the undoped gallium nitride homoepitaxial thin film infiltration layer, wherein the growth rate is controlled to be 15-20nm/min, and the growth thickness is 200 nm.

Further, step S3 is to raise the temperature to 1000 deg.C within 2min after S2 is finished, and to maintain the pressure in the reaction chamber at 75torr, N₂:H₂:NH₃The ratio is 25: 25: 50, the total gas flow is unchanged at 120-150slm/min, an N-type conductive GaN epitaxial layer is grown, TMGa is introduced, and SiH is introduced₄As N-type dopant, the growth rate is 30-40um/min, the growth thickness is 1000nm, and the Si doping concentration is 3-5E 18cm^-3The temperature was reduced to 850 ℃ in four minutes, the pressure in the reaction chamber was increased to 200torr, and the introduction of H was stopped₂Hold N₂:NH₃The ratio was 50:50, total gas flow 120-.

Further, S4 is to begin growing a GaN stress control layer after S3 is finished, and to introduce TMGa and SiH₄The growth rate is 10-12nm/min, the growth thickness is 100-120nm, the Si doping concentration is 1-3E17cm^-3。

Further, S5 is specifically a GaN/InGaN superlattice electron storage layer grown after S4 is finished, the layer is of a GaN/InGaN superlattice structure with 3 periods, and the thickness of a single period is 11 nm; wherein the thickness of the GaN layer is 10nm, and the growth temperature is 870 ℃; the growth temperature of the InGaN layer with the thickness of 1nm is 820 ℃, the Ga source is improved by using the triethyl gallium TEGa, and the In source is provided by the trimethyl indium TMIn.

Further, S6 is specificallyAfter S5, growing an InGaN/GaN multi-quantum well light-emitting epitaxial layer which is of an InGaN/GaN periodic structure with 6 periods, wherein the thickness of a single period is 20nm, a triethylgallium (TEGa) is used for improving a Ga source, and a trimethylindium (TMIn) is used for providing an In source; in which the InGaN well layer is 3nm thick, using N₂/NH₃Atmosphere, total gas flow 120-; the GaN barrier layer has a thickness of 17nm, and comprises three parts, namely a layer of Cap1 before the well layer grows and a layer of Cap2 after the well layer grows, the thickness of the Cap1 layer and the Cap2 layer are respectively 1nm and 3nm, the growth conditions of the Cap1 layer and the Cap2 layer are completely the same as the well layer conditions except that a TMIn source is not introduced, the thickness of the other barrier layer is 13nm, and the layer is introduced with H for processing the In segregation growth₂By using N₂:H₂:NH₃The ratio of 4:1:5, the total gas flow rate is not changed at 120-150slm/min, the growth temperature is 870 ℃, SiH4 is adopted for doping, and the concentration is 1E18cm^-3。

Further, S7 is the growth of composite P-type GaN layer after S6 is finished, the growth pressure is 200torr, N₂:H₂:NH₃The ratio is 2:4:4, the total gas flow is kept at 120-150slm/min and is kept consistent; the composite PGaN layer consists of three parts, namely a low-temperature LT-PGaN layer, a high-temperature HT-PGaN layer and a PP layer in sequence; wherein the LT-PGaN layer has a temperature of 750 ℃, TEGa and Cp2Mg are used for providing Ga and Mg sources, the thickness is 30nm, and the Mg doping concentration is 1E19cm^-3(ii) a Wherein the HT-PGaN layer is grown at 960 deg.C to 60nm with Ga and Mg source and LT-PGaN, and Mg doping concentration is 5E19cm^-3(ii) a Wherein the growth temperature of the PP layer is 900 ℃, Ga and Mg sources are used as LT-PGaN, the growth thickness is 3nm, and the Mg doping concentration is 1E20cm^-3。

Further, the temperature was lowered to 750 ℃ after completion of S7, and H was turned off₂And NH₃Into pure N₂Environment, N₂Carrying out in-situ annealing for 5min at the flow rate of 130 slm/min; and (5) cooling after the annealing is finished, and finishing the growth.

Compared with the prior art, the invention has the following advantages:

the invention provides an epitaxial method for growing a blue light-emitting diode on an m-plane gallium nitride substrate, which comprises the steps of growing the m-plane blue light-emitting diode on an m-plane gallium nitride template substrate by using a metal organic chemical vapor deposition method to obtain an epitaxial surface with a smooth surface, and obtaining the blue light-emitting diode with the light-emitting wavelength of 465nm by using a stress control layer and a special light-emitting quantum well growing method. The planar surface obtained by the M-surface GaN homoepitaxy is realized, and the effective incorporation of the InGaN layer quantum well layer In is realized, so that the excitation of the blue light quantum well is realized.

Drawings

FIG. 1 is an epitaxial structural view of the present invention;

FIG. 2 is a schematic view showing the growth of a light emitting quantum well layer in the present invention;

FIG. 3 is a schematic representation of the monitored reflectance (upper) and temperature (lower) curves during actual growth of the present invention;

FIG. 4 is an optical microscope image of the surface of the grown epitaxial wafer after the completion of the practice of the present invention;

fig. 5 shows the illumination pattern (left) and the wavelengths measured by the spectrometer after the current is applied to the grown epitaxial wafer after the present invention is implemented.

Detailed Description

In order to make the technical solutions of the present application better understood by those skilled in the art, the technical solutions of the present application will be clearly and completely described below in conjunction with the embodiments of the present application, and it is obvious that the described embodiments are only some embodiments of the present application, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It is noted that the term "comprising" in the description and claims of the present application is intended to cover a non-exclusive inclusion, e.g. a method comprising a list of steps is not necessarily limited to those steps explicitly listed, but may include other steps not explicitly listed or inherent to such methods. The embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail with reference to examples.