CN212542464U

CN212542464U - Ultraviolet LED epitaxial wafer grown on Si substrate

Info

Publication number: CN212542464U
Application number: CN202021166603.6U
Authority: CN
Inventors: 高芳亮
Original assignee: Yixing Qurong Photoelectric Technology Co ltd
Current assignee: Yixing Qurong Photoelectric Technology Co ltd
Priority date: 2020-06-22
Filing date: 2020-06-22
Publication date: 2021-02-12
Anticipated expiration: 2030-06-22

Abstract

The utility model discloses an ultraviolet LED epitaxial wafer growing on a Si substrate, which comprises an AlN buffer layer, a GaN buffer layer, an AlGaN buffer layer, a non-doped AlGaN layer, an n-type doped AlGaN layer, an AlGaN multi-quantum well layer, an electronic barrier layer and a p-type doped GaN film growing on the Si substrate; first grooves arranged in an array manner are formed in the GaN buffer layer; the lower part of the AlGaN buffer layer is deposited in the first groove, and second grooves which are arranged in an array manner are formed on the AlGaN buffer layer; the first groove and the second groove are not overlapped in the vertical direction; a lower portion of the undoped AlGaN layer is deposited within the second trench. The utility model discloses ultraviolet LED epitaxial wafer that grows on the Si substrate defect density is low, crystallization quality is good, through the sculpture many times, increases the horizontal epitaxy of AlGaN, effectively inhibits the dislocation and up extends, has the advantage of growing high crystal quality ultraviolet LED epitaxial wafer.

Description

Ultraviolet LED epitaxial wafer grown on Si substrate

Technical Field

The utility model relates to a LED epitaxial wafer technical field especially relates to an ultraviolet LED epitaxial wafer of growth on Si substrate.

Background

The GaN-based ultraviolet LED epitaxial material and the GaN-based ultraviolet LED epitaxial device are used as the key of the third-generation semiconductor material and the third-generation semiconductor device, can be applied to the fields of sterilization, disinfection, medical instruments and the like, and are developed abnormally rapidly in recent years.

At present, high-quality GaN materials are generally manufactured by a heteroepitaxy method, and because different substrates can directly influence the lattice quality of a grown epitaxial layer, the selection of the substrate is very important. Generally, the selection of the substrate needs to follow several principles, such as lattice constant matching, thermal expansion coefficient matching, proper price and the like; in addition, the choice of different substrates causes process differences from epitaxy to subsequent LED chip fabrication. Currently, most GaN-based uv LEDs are based on epitaxial growth on sapphire, SiC and Si substrates. Although some research progress has been made, the following problems are faced: (1) due to the poor thermal conductivity of the sapphire substrate (only 25W/m.K), heat generated during the operation of the ultraviolet LED device is difficult to conduct, and the service life and the performance of the LED device are influenced; (2) the large size of sapphire and SiC substrates is expensive, resulting in high LED manufacturing costs. The Si substrate is not only low in price and mature in production process, but also is one of the first materials for realizing commercialization of large-area and low-cost LED optoelectronic devices, and therefore, LEDs using Si as a substrate have attracted extensive research interest from many scientific research institutes at home and abroad. However, because of the large lattice mismatch and thermal mismatch between the Si material and the epitaxially grown nitride material, in order to realize the growth of a high-quality nitride material on the Si substrate, the major defects such as lattice mismatch, thermal mismatch, crystal dislocation, stacking fault and the like still need to be overcome, which severely limits the large-scale application of the commercial production of the ultraviolet LED.

SUMMERY OF THE UTILITY MODEL

In order to overcome the defects of the prior art, one of the purposes of the present invention is to provide an ultraviolet LED epitaxial wafer grown on a Si substrate, which has low defect density, good crystallization quality, and good electrical and optical properties.

The second objective of the utility model is to provide a preparation method of ultraviolet LED epitaxial wafer of growth on the Si substrate, through etching many times, increase the horizontal epitaxy of AlGaN, effectively restrain the dislocation and up extend, have the advantage of growing high crystal quality ultraviolet LED epitaxial wafer.

The utility model discloses an one of the purpose adopts following technical scheme to realize:

an ultraviolet LED epitaxial wafer grown on a Si substrate comprises an AlN buffer layer grown on the Si substrate, a GaN buffer layer grown on the AlN buffer layer, an AlGaN buffer layer grown on the GaN buffer layer, a non-doped AlGaN layer grown on the AlGaN buffer layer, an n-type doped AlGaN layer grown on the non-doped AlGaN layer, an AlGaN multi-quantum well layer grown on the n-type doped AlGaN layer, an electron blocking layer grown on the AlGaN multi-quantum well layer, and a p-type doped GaN thin film grown on the electron blocking layer;

first grooves arranged in an array manner are formed in the upper part of the GaN buffer layer;

the lower part of the AlGaN buffer layer is deposited in the first groove, and the upper part of the AlGaN buffer layer is provided with second grooves which are arranged in an array; the first trench and the second trench do not overlap in a vertical direction;

a lower portion of the undoped AlGaN layer is deposited within the second trench.

Preferably, the first grooves are first trapezoidal stripe grooves with the top width larger than the bottom width, the depth of the first trapezoidal stripe grooves is 50-80 nm, the top width is 100-200 nm, the bottom width is 50-100nm, and the interval is 100-200 nm; the second grooves are second trapezoidal stripe grooves with the top width larger than the bottom width, the depth of the second trapezoidal stripe grooves is 100-150 nm, the top width is 100-200 nm, the bottom width is 50-100nm, and the interval is 100-200 nm.

Preferably, the Si substrate is a Si (111) crystal orientation substrate; the AlN buffer layer is 5-50 nm thick; the thickness of the GaN buffer layer is 100-300 nm; the thickness of the AlGaN buffer layer is 300-500 nm; the thickness of the non-doped AlGaN layer is 500-800 nm; the n-type doped AlGaN layer is doped with Si with the doping concentration of 1 multiplied by 10¹⁷～1×10²⁰cm^-3The thickness of the n-type doped AlGaN layer is 3-5 mu m; the AlGaN multi-quantum well layer is Al with 7-10 periods_0.1Ga_0.9N well layer and Al_0.25Ga_0.75N barrier layer of Al_0.1Ga_0.9The thickness of the N well layer is 2-3 nm, and Al is_0.25Ga_0.75The thickness of the N barrier layer is 10-13 nm; the electron blocking layer is Al_0.15Ga_0.85The thickness of the electron blocking layer is 20-50 nm; the thickness of the p-type doped GaN film is 300-350 nm.

The second purpose of the utility model is realized by adopting the following technical scheme:

a preparation method of an ultraviolet LED epitaxial wafer grown on a Si substrate is characterized by comprising the following steps:

substrate selection: selecting a Si substrate;

and (3) growing an AlN buffer layer: growing an AlN buffer layer on the Si substrate;

and (3) epitaxial growth of a GaN buffer layer: epitaxially growing a GaN buffer layer on the AlN buffer layer;

and an AlGaN buffer layer epitaxial growth step: etching the GaN buffer layer, and etching first grooves arranged in an array on the upper part of the GaN buffer layer; then, growing an AlGaN buffer layer on the GaN buffer layer, wherein the lower part of the AlGaN buffer layer is deposited in the first groove;

and (3) epitaxial growth of the undoped AlGaN layer: etching the AlGaN buffer layer, and etching second grooves which are arranged in an array manner on the upper part of the AlGaN buffer layer, wherein the first grooves and the second grooves are not overlapped in the vertical direction; then, growing a non-doped AlGaN layer on the AlGaN buffer layer, wherein the lower part of the non-doped AlGaN layer is deposited in the second trench;

and (3) epitaxial growth of the n-type doped AlGaN layer: epitaxially growing an n-type doped AlGaN layer on the undoped AlGaN layer;

and an AlGaN multi-quantum well layer epitaxial growth step: epitaxially growing an AlGaN multi-quantum well layer on the n-type doped AlGaN layer;

and (3) epitaxial growth of the electron barrier layer: epitaxially growing an electronic barrier layer on the AlGaN multi-quantum well layer;

and (3) epitaxial growth of the p-type doped GaN film: and epitaxially growing a p-type doped GaN film on the electron blocking layer.

Preferably, in the AlN buffer layer growing step, an AlN buffer layer is grown by a magnetron sputtering method, the growth temperature is 400-500 ℃, and the thickness of the AlN buffer layer is 5-50 nm.

Preferably, in the step of epitaxial growth of the GaN buffer layer, a molecular beam epitaxial growth method is adopted to grow the GaN buffer layer on the AlN buffer layer, the substrate temperature is 500-600 ℃, and the pressure of the reaction chamber is 4.0-5.0 multiplied by 10^-5Pa, the beam current ratio V/III value is 30-40, and the growth speed is 0.6-0.8 ML/s.

Preferably, in the epitaxial growth step of the AlGaN buffer layer, the GaN buffer layer is etched by adopting ICP (inductively coupled plasma), and first trapezoidal stripe grooves with the top width larger than the bottom width are etched, wherein the depth of each first trapezoidal stripe groove is 50-80 nm, the top width is 100-200 nm, the bottom width is 50-100nm, and the interval is 100-200 nm; and then, growing an AlGaN buffer layer on the GaN buffer layer by adopting a metal organic chemical vapor deposition method, wherein the process conditions are as follows: the pressure in the reaction chamber is 50to 300torr, the temperature of the Si substrate is 1000 to 1060 ℃, the beam current ratio V/III is 3000 to 5000, and the growth rate is 2 to 4 μm/h.

Preferably, in the step of epitaxial growth of the undoped AlGaN layer, the AlGaN buffer layer is etched by using ICP, a second trapezoidal stripe groove having a top width larger than a bottom width is etched, the depth of the second trapezoidal stripe groove is 100 to 150nm, the top width is 100 to 200nm, the bottom width is 50to 100nm, the interval is 100 to 200nm, and the second trapezoidal stripe groove and the first trapezoidal stripe groove are not overlapped in the vertical direction; and then, growing a non-doped AlGaN layer on the AlGaN buffer layer by adopting a metal organic chemical vapor deposition method, wherein the process conditions are as follows: the pressure in the reaction chamber is 50to 300torr, the temperature of the Si substrate is 1000 to 1060 ℃, the beam current ratio V/III is 3000 to 5000, and the growth rate is 2 to 4 μm/h.

Preferably, in the step of epitaxially growing the n-type doped AlGaN layer, a metal organic chemical vapor deposition method is used to grow the n-type doped AlGaN layer on the undoped AlGaN layer, and the process conditions are as follows: reaction ofThe chamber pressure is 50-300 torr, the Si substrate temperature is 1000-1060 ℃, the beam current ratio V/III is 3000-5000, and the growth rate is 2-4 μm/h; the n-type doped AlGaN layer is doped with Si with the doping concentration of 1 multiplied by 10¹⁷～1×10²⁰cm^-3。

Preferably, in the step of epitaxial growth of the AlGaN multi-quantum well layer, Al is grown on the n-type doped AlGaN layer for 7-10 periods by a metal organic chemical vapor deposition method_0.1Ga_0.9N well layer/Al_0.25Ga_0.75N base layers, the process conditions are as follows: the pressure in the reaction chamber is 50to 300torr, the temperature of the Si substrate is 1000 to 1060 ℃, the beam current ratio V/III is 3000 to 5000, and the growth rate is 2 to 4 μm/h.

Preferably, in the electron blocking layer epitaxial growth step, Al is grown on the AlGaN multi-quantum well layer by using a metal organic chemical vapor deposition method_0.15Ga_0.85The process conditions of the N electron blocking layer are as follows: the pressure of the reaction chamber is 50-300 torr, the temperature of the Si substrate is 1000-1060 ℃, the beam current ratio V/III is 3000-5000, and the growth rate is 2-4 μm/h.

Preferably, in the p-type doped GaN film epitaxial growth step, a metal organic chemical vapor deposition method is adopted to grow a p-type doped GaN film on the electron blocking layer, and the process conditions are as follows: the pressure in the reaction chamber is 50to 300torr, the temperature of the Si substrate is 1000 to 1060 ℃, the beam current ratio V/III is 3000 to 5000, and the growth rate is 2 to 4 μm/h.

Compared with the prior art, the beneficial effects of the utility model reside in that:

(1) the utility model provides an ultraviolet LED epitaxial wafer of growth on Si substrate, through at GaN buffer layer and AlGaN buffer layer design slot pattern, at the epitaxial growth in-process, at first at the lateral wall nucleation of slot, grow, along with going on of epitaxial growth, horizontal growth is obvious gradually, dislocation line horizontal extension and merge, along with further going on of epitaxial growth, the mismatch dislocation does not further upwards extend. The artificial increase of the growth mode of transverse overgrowth reduces dislocation upward extension, can further reduce the defect density of an epitaxial layer, obtains a material with high crystal quality, and realizes the growth of a high-performance epitaxial wafer, thereby being beneficial to improving the radiation recombination efficiency of carriers and improving the performance of a light-emitting diode.

(2) The utility model provides a growth ultraviolet LED epitaxial wafer on Si substrate prepares out high quality AlGaN layer, has favorable improved the radiation recombination efficiency of current carrier, reduces non-radiation recombination efficiency, can increase substantially emitting diode's performance, is expected to prepare out high-efficient ultraviolet LED's device.

Drawings

Fig. 1 is a first schematic view of a cross-sectional structure of an ultraviolet LED epitaxial wafer prepared in embodiment 1 of the present invention;

fig. 2 is a second schematic view of the cross-sectional structure of the ultraviolet LED epitaxial wafer prepared in embodiment 1 of the present invention;

fig. 3 is an Electroluminescence (EL) spectrum of an ultraviolet LED epitaxial wafer prepared in example 1 of the present invention.

In the figure: 10. a Si substrate; 11. an AlN buffer layer; 12. a GaN buffer layer; 13. an AlGaN buffer layer; 14. a non-doped AlGaN layer; 15. an n-type doped AlGaN layer; 16. an AlGaN multi-quantum well layer; 17. an electron blocking layer; 18. and (3) doping a GaN thin film in a p type.

Detailed Description

The present invention will be further described with reference to the accompanying drawings and the detailed description, and it should be noted that the embodiments or technical features described below can be arbitrarily combined to form a new embodiment without conflict.

As shown in fig. 1-2, an ultraviolet LED epitaxial wafer grown on a Si substrate includes an AlN buffer layer 11 grown on a Si substrate 10, a GaN buffer layer 12 grown on the AlN buffer layer 11, an AlGaN buffer layer 13 grown on the GaN buffer layer 12, an undoped AlGaN layer 14 grown on the AlGaN buffer layer 13, an n-type doped AlGaN layer 15 grown on the undoped AlGaN layer 14, an AlGaN multi-quantum well layer 16 grown on the n-type doped AlGaN layer 15, an electron blocking layer 17 grown on the AlGaN multi-quantum well layer 16, and a p-type doped GaN thin film 18 grown on the electron blocking layer 17; first grooves arranged in an array are formed in the upper part of the GaN buffer layer 12; the lower part of the AlGaN buffer layer 13 is deposited in the first groove, and the upper part of the AlGaN buffer layer 13 is provided with second grooves arranged in an array; the first groove and the second groove are not overlapped in the vertical direction; a lower portion of the undoped AlGaN layer 14 is deposited within the second trench.

The embodiment of the utility model provides a through first slot and second slot design, in the epitaxial growth in-process, the artificial growth mode that increases transversely and cross the growth reduces dislocation and upwards extends, can further reduce the defect density of epitaxial layer, obtains the material of high crystal quality, realizes the growth of high performance epitaxial wafer.

The embodiment of the utility model discloses ultraviolet LED epitaxial wafer, from the bottom up includes the Si substrate in proper order, AlN buffer layer 11, GaN buffer layer 12, AlGaN buffer layer 13, undoped AlGaN layer 14, n type dopes AlGaN layer 15, AlGaN multiple quantum well layer 16, electron barrier layer 17 and p type dopes GaN film 18, in this a plurality of hierarchy structures, be UV LED's basic structure on the Si substrate, wherein preceding 4 layers of buffer layer structure (AlN buffer layer 11, GaN buffer layer 12, AlGaN buffer layer 13, undoped AlGaN layer 14) are AlGaN film (n type dopes AlGaN layer 15) in order to obtain high crystal quality, lay the basis for growing dark ultraviolet active layer (n layer, multiple quantum well, p layer constitution); the utility model discloses a this kind of compound mode, including the groove structure, realized adopting the AlGaN film that can obtain high crystal quality under the condition of simple buffer layer structure, and the buffer layer structure that adopts very complicated among the prior art is adopted to reduce the mismatch dislocation between AlGaN and the Si substrate by a few ways.

In a further embodiment, the first grooves are first trapezoidal stripe grooves with the top width larger than the bottom width, the depth of the first trapezoidal stripe grooves is 50-80 nm, the top width is 100-200 nm, the bottom width is 50-100nm, and the interval is 100-200 nm; the second grooves are second trapezoidal stripe grooves with the top width larger than the bottom width, the depth of the second trapezoidal stripe grooves is 100-150 nm, the top width is 100-200 nm, the bottom width is 50-100nm, and the interval is 100-200 nm.

The embodiment of the utility model provides a set up first trapezoidal stripe slot on GaN buffer layer 12, set up the trapezoidal stripe slot of second on AlGaN buffer layer 13, help in the lateral wall nucleation to further transversely extend, merge in the epitaxial growth in-process, avoid direct epitaxial growth upwards, reduce the dislocation and up extend. Certainly, the first trench and the second trench are not limited to be trapezoidal stripe trenches, but may also be island trenches (similar to a Chinese character 'tian'), and the first trench and the second trench are also set to be island trenches, so that the defect density of the epitaxial layer can be reduced, a material with high crystal quality can be obtained, and the growth of a high-performance epitaxial wafer can be realized.

The utility model discloses first trapezoidal stripe slot and the trapezoidal stripe slot of second do not overlap in the vertical direction, though before carrying out the etching for the second time, the product can obtain the film of higher crystal quality after certain thickness of epitaxial growth, but at the slot growth position, defect density is generally all higher. In other regions, i.e., non-trench regions, the dislocation line density is gradually reduced due to the lateral epitaxial growth, and the crystal quality is higher than that of the trench regions. Therefore, when the trench is formed for the second time, a region having a high defect density is selected, that is, the first trench and the second trench are not overlapped with each other in the vertical direction, avoiding a region having a high defect density.

As a further implementation mode, the Si substrate is an Si (111) crystal orientation substrate, the utility model discloses use Si as the substrate, the substrate is easily obtained, and the low price is favorable to reduction in production cost.

In a further embodiment, the AlN buffer layer 11 has a thickness of 5 to 50 nm; the thickness of the GaN buffer layer 12 is 100-300 nm; the AlGaN buffer layer 13 has a thickness of 300-500 nm; the thickness of the undoped AlGaN layer 14 is 500-800 nm; the n-type doped AlGaN layer 15 is doped with Si at a doping concentration of 1X 10¹⁷～1×10²⁰cm^-3The thickness of the n-type doped AlGaN layer 15 is 3 to 5 μm.

In a further embodiment, the AlGaN multi-quantum well layer 16 is Al having 7 to 10 periods_0.1Ga_0.9N well layer and Al_0.25Ga_0.75N barrier layer of Al_0.1Ga_0.9The thickness of the N well layer is 2-3 nm, and Al is_0.25Ga_0.75The thickness of the N barrier layer is 10-13 nm. Luminous wavelength of LED and band gap of materialIn relation to the above, the Al component determines the emission wavelength of the ultraviolet LED, and in practical applications, the components may be adjusted according to the actually required emission wavelength, or may be replaced with other quantum well materials (well layer and barrier layer).

As a further embodiment, the electron blocking layer 17 is Al_0.15Ga_0.85An N electron blocking layer, wherein the thickness of the electron blocking layer 17 is 20-50 nm; the thickness of the p-type doped GaN film 18 is 300-350 nm. The electron barrier layer 17 is used for preventing electrons from overflowing during current injection, and the electrons cannot be completely limited in the quantum well for radiative recombination; the band gap of the required material is slightly higher than that of the well layer, but in order to avoid adopting other materials to bring extra lattice mismatch, the embodiment of the present invention adopts the same type of material as the AlGaN multiple quantum well layer 16 as the electron blocking layer 17.

The embodiment of the utility model provides an ultraviolet LED epitaxial wafer of growth on Si substrate, through at GaN buffer layer 12 and AlGaN buffer layer 13 design slot pattern, at the epitaxial growth in-process, at first at the lateral wall nucleation of slot, grow, along with going on of epitaxial growth, lateral growth is obvious gradually, and the dislocation line transversely extends and merges, and along with further going on of epitaxial growth, the mismatch dislocation does not further upwards extend. The artificial increase of the growth mode of transverse overgrowth reduces dislocation upward extension, can further reduce the defect density of an epitaxial layer, obtains a material with high crystal quality, and realizes the growth of a high-performance epitaxial wafer, thereby being beneficial to improving the radiation recombination efficiency of carriers and improving the performance of a light-emitting diode.

Furthermore, the embodiment of the utility model provides an ultraviolet LED epitaxial wafer of growth on the Si substrate prepares out the high quality AlGaN layer, has favorable improved the radiation recombination efficiency of carrier, reduces non-radiation recombination efficiency, can increase substantially emitting diode's performance, is expected to prepare out high-efficient ultraviolet LED's device.

substrate selection: selecting a Si substrate;

growth of the AlN buffer layer 11: growing an AlN buffer layer 11 on the Si substrate 10;

epitaxial growth of the GaN buffer layer 12: epitaxially growing a GaN buffer layer 12 on the AlN buffer layer 11;

epitaxial growth of the AlGaN buffer layer 13: etching the GaN buffer layer 12, and etching first grooves arranged in an array on the upper part of the GaN buffer layer 12; next, growing an AlGaN buffer layer 13 on the GaN buffer layer 12, and depositing a lower portion of the AlGaN buffer layer 13 in the first trench;

and (3) epitaxially growing the undoped AlGaN layer 14: etching the AlGaN buffer layer 13, and etching second grooves which are arranged in an array manner on the upper part of the AlGaN buffer layer 13, wherein the first grooves and the second grooves are not overlapped in the vertical direction; then, growing a non-doped AlGaN layer 14 on the AlGaN buffer layer 13, and depositing the lower portion of the non-doped AlGaN layer 14 in the second trench;

and (3) epitaxial growth of the n-type doped AlGaN layer 15: epitaxially growing an n-type doped AlGaN layer 15 on the undoped AlGaN layer 14;

and an AlGaN multi-quantum well layer 16 epitaxial growth step: epitaxially growing an AlGaN multi-quantum well layer 16 on the n-type doped AlGaN layer 15;

and (3) an epitaxial growth step of the electron blocking layer 17: epitaxially growing an electron blocking layer 17 on the AlGaN multi-quantum well layer 16;

and (3) epitaxial growth of the p-type doped GaN film 18: a p-type doped GaN thin film 18 is epitaxially grown on the electron blocking layer 17.

In a further embodiment, in the step of growing the AlN buffer layer 11, the AlN buffer layer 11 is grown by a magnetron sputtering method at a growth temperature of 400 to 500 ℃ and a thickness of the AlN buffer layer 11 of 5 to 50 nm.

In a further embodiment, in the step of epitaxially growing the GaN buffer layer 12, the GaN buffer layer 12 is grown on the AlN buffer layer 11 by a molecular beam epitaxy method at a substrate temperature of 500 to 600 ℃ and a reaction chamber pressure of 4.0 to 5.0X 10^-5Pa, the beam current ratio V/III value is 30-40, and the growth speed is 0.6-0.8 ML/s.

In the further implementation mode, in the epitaxial growth step of the AlGaN buffer layer 13, etching the GaN buffer layer 12 by adopting ICP (inductively coupled plasma), and etching a first trapezoidal stripe groove with the top width larger than the bottom width, wherein the depth of the first trapezoidal stripe groove is 50-80 nm, the top width is 100-200 nm, the bottom width is 50-100nm, and the interval is 100-200 nm; next, an AlGaN buffer layer 13 is grown on the GaN buffer layer 12 by using a metal organic chemical vapor deposition method under the following process conditions: the pressure in the reaction chamber is 50to 300torr, the temperature of the Si substrate is 1000 to 1060 ℃, the beam current ratio V/III is 3000 to 5000, and the growth rate is 2 to 4 μm/h.

As a further implementation manner, in the epitaxial growth step of the undoped AlGaN layer 14, the AlGaN buffer layer 13 is etched by using ICP, to etch a second trapezoidal stripe groove with a top width larger than a bottom width, the depth of the second trapezoidal stripe groove is 100 to 150nm, the top width is 100 to 200nm, the bottom width is 50to 100nm, the interval is 100 to 200nm, and the second trapezoidal stripe groove and the first trapezoidal stripe groove are not overlapped in the vertical direction; next, growing an undoped AlGaN layer 14 on the AlGaN buffer layer 13 by using a metal organic chemical vapor deposition method, wherein the process conditions are as follows: the pressure in the reaction chamber is 50to 300torr, the temperature of the Si substrate is 1000 to 1060 ℃, the beam current ratio V/III is 3000 to 5000, and the growth rate is 2 to 4 μm/h.

As a further embodiment, in the step of epitaxially growing the n-type doped AlGaN layer 15, the n-type doped AlGaN layer 15 is grown on the undoped AlGaN layer 14 by using a metal organic chemical vapor deposition method under the following process conditions: the pressure of the reaction chamber is 50-300 torr, the temperature of the Si substrate is 1000-1060 ℃, the beam current ratio V/III is 3000-5000, and the growth rate is 2-4 mu m/h; the n-type doped AlGaN layer 15 is doped with Si at a doping concentration of 1X 10¹⁷～1×10²⁰cm^-3。

In a further embodiment, in the step of epitaxially growing the AlGaN multi-quantum well layer 16, Al is grown on the n-type doped AlGaN layer 15 for 7 to 10 periods by metal organic chemical vapor deposition_0.1Ga_0.9N well layer/Al_0.25Ga_0.75N base layers, the process conditions are as follows: the pressure in the reaction chamber is 50to 300torr, the temperature of the Si substrate is 1000 to 1060 ℃, the beam current ratio V/III is 3000 to 5000, and the growth rate is 2 to 4 μm/h.

As a further embodiment, in the electron barrier layer 17 epitaxial growth step, Al is grown on the AlGaN multi-quantum well layer 16 using a metal organic chemical vapor deposition method_0.15Ga_0.85The process conditions of the N electron blocking layer 17 are as follows: the pressure in the reaction chamber is 50to 300torr, the temperature of the Si substrate is 1000 to 1060 ℃, the beam current ratio V/III is 3000 to 5000, and the growth rate is 2 to 4 μm/h.

As a further embodiment, in the step of epitaxially growing the p-type doped GaN film 18, the p-type doped GaN film 18 is grown on the electron blocking layer 17 by metal organic chemical vapor deposition under the following process conditions: the pressure in the reaction chamber is 50to 300torr, the temperature of the Si substrate is 1000 to 1060 ℃, the beam current ratio V/III is 3000 to 5000, and the growth rate is 2 to 4 μm/h.

The embodiment of the utility model provides a grow at the ultraviolet LED epitaxial wafer and the preparation method of Si substrate 10, the thickness of a plurality of layers and the technological parameter of preparation, especially in the part of slot technology, are the cooperation slot pattern, help in the lateral wall nucleation of pattern at the epitaxial growth initial stage, help horizontal growth and merge in the middle of the epitaxial growth, obtain the film (layer) of high crystal quality.

The embodiment of the utility model provides a preparation method of ultraviolet LED epitaxial wafer of growth on Si substrate, adopt molecular beam epitaxy technology, ICP etching process and metal organic chemical vapor deposition technology combine together, adopt molecular beam epitaxy technology growth AlGaN buffer layer 13 earlier, then adopt ICP etching process sculpture out regular slot, then adopt metal chemical vapor deposition technology to be favorable to AlGaN nucleation in the slot, and lateral growth, merge, make dislocation line lateral expansion, it upwards extends to restrain the dislocation line, grow out the AlGaN film of high crystal quality, and prepare out high quality AlGaN multiple quantum well layer 16, the radiation recombination efficiency of carrier has been favorable to having improved, ultraviolet LED's luminous efficacy can be increased substantially.

In addition, the utility model combines the molecular beam epitaxy process, the ICP etching process and the metal organic chemical vapor deposition process to prepare the high-quality non-doped AlGaN layer 14 with the thickness of 500-800 nm; when the non-doped AlGaN layer 14 reaches 500-800 nm, AlGaN is in a completely relaxed state, so that the epitaxial growth of a high-quality n-type doped AlGaN film in the later period is facilitated, and a device of a high-efficiency ultraviolet LED is expected to be prepared.

Meanwhile, the growth process provided by the embodiment of the utility model is unique, simple and feasible, and has repeatability.

Example 1

As shown in fig. 1-2, the ultraviolet LED epitaxial wafer grown on a Si substrate of the present embodiment includes an AlN buffer layer 11 grown on a Si substrate 10, a GaN buffer layer 12 grown on the AlN buffer layer 11, an AlGaN buffer layer 13 grown on the GaN buffer layer 12, an undoped AlGaN layer 14 grown on the AlGaN buffer layer 13, an n-type doped AlGaN layer 15 grown on the undoped AlGaN layer 14, an AlGaN multi-quantum well layer 16 grown on the n-type doped AlGaN layer 15, an electron blocking layer 17 grown on the AlGaN multi-quantum well layer 16, and a p-type doped GaN thin film 18 grown on the electron blocking layer 17.

The preparation method of the ultraviolet LED epitaxial wafer grown on the Si substrate of the present embodiment includes the following steps:

(1) selecting a substrate: adopting a Si (111) crystal orientation substrate;

(2) growth of AlN buffer layer 11: growing the AlN buffer layer 11 by adopting a magnetron sputtering Method (MS), wherein the growth temperature is 400 ℃, and the film thickness is 5nm to obtain the AlN buffer layer 11;

(3) epitaxial growth of the GaN buffer layer 12: adopting molecular beam epitaxial growth process, the substrate temperature is 500 deg.C, and the pressure in the reaction chamber is 4.0 × 10^-5Growing a GaN buffer layer 12 with the thickness of 100nm on the AlN buffer layer 11 under the conditions of Pa, the value of the beam current ratio V/III of 30 and the growth speed of 0.6 ML/s;

(4) the AlGaN buffer layer 13 is epitaxially grown: etching the GaN buffer layer 12 by adopting ICP (inductively coupled plasma), and etching trapezoidal stripe grooves with the top width larger than the bottom width, the depth of 50nm, the top width of 100nm, the bottom width of 50nm and the interval of 100 nm; then, a metal organic chemical vapor deposition process is adopted, and the process conditions are as follows: the pressure of the reaction chamber is 50torr, the temperature of the Si substrate is 1000 ℃, the beam current ratio V/III is 3000, the growth rate is 2 mu m/h, and an AlGaN buffer layer 13 with the thickness of 300nm is grown on the GaN buffer layer 12;

(5) epitaxial growth of the undoped AlGaN layer 14: etching the AlGaN buffer layer 13 by adopting ICP (inductively coupled plasma), and etching trapezoidal stripe grooves with the top width larger than the bottom width, the depth of the trapezoidal stripe grooves being 100nm, the top width of the trapezoidal stripe grooves being 100nm, the bottom width of the trapezoidal stripe grooves being 50nm, and the interval of the trapezoidal stripe grooves being 100nm, wherein the etched trapezoidal stripe grooves are not overlapped with the grooves etched in the step (4) in the vertical direction; then, a metal organic chemical vapor deposition process is adopted, and the process conditions are as follows: the pressure of the reaction chamber is 50torr, the temperature of the Si substrate is 1000 ℃, the beam current ratio V/III is 3000, the growth rate is 2 mu m/h, and a non-doped AlGaN layer 14 with the thickness of 500nm is grown on the obtained AlGaN buffer layer 13;

(6) epitaxial growth of the n-type doped AlGaN layer 15: the metal organic chemical vapor deposition process is adopted, and the process conditions are as follows: growing an n-type doped AlGaN layer 15 with the thickness of 3 microns on the non-doped AlGaN layer 14 obtained in the step (5) under the conditions that the pressure of a reaction chamber is 50torr, the temperature of a Si substrate is 1000 ℃, the beam current ratio V/III is 3000 and the growth rate is 2 microns/h;

(7) epitaxial growth of AlGaN multiple quantum well layer 16: the metal organic chemical vapor deposition process is adopted, and the process conditions are as follows: growing an AlGaN multiple quantum well on the n-type doped AlGaN layer 15 obtained in the step (6) under the conditions that the pressure of a reaction chamber is 50torr, the temperature of a Si substrate is 1000 ℃, the beam current ratio V/III is 3000 and the growth rate is 2 mu m/h; AlGaN MQW layer 16 is 7 periods of Al_0.1Ga_0.9N well layer/Al_0.25Ga_0.75N barrier layer of Al_0.1Ga_0.9The thickness of the N well layer is 2nm, and Al_0.25Ga_0.75The thickness of the N barrier layer is 10 nm;

(8) epitaxial growth of the electron blocking layer 17: the metal organic chemical vapor deposition process is adopted, and the process conditions are as follows: the pressure of the reaction chamber is 50torr, the temperature of the Si substrate is 1000 ℃, the beam current ratio V/III is 3000, the growth rate is 2 mu m/h, and Al with the thickness of 20nm is grown on the AlGaN multi-quantum well layer 16 obtained in the step (7)_0.15Ga_0.85An N electron blocking layer 17;

(10) epitaxial growth of p-type doped GaN thin film 18: the metal organic chemical vapor deposition process is adopted, and the process conditions are as follows: and (3) growing a p-type doped GaN film 18 with the thickness of 300nm on the electron blocking layer 17 obtained in the step (8) under the conditions that the pressure of the reaction chamber is 50torr, the temperature of the Si substrate is 1000 ℃, the beam current ratio V/III is 3000, and the growth rate is 2 mu m/h.

The roughness RMS value of the p-type doped GaN film 18 prepared in the example is determined to be lower than 1.6 nm; indicating that a high quality p-type doped GaN film 18 was obtained that was shown to be smooth.

Fig. 3 is an EL spectrum of the ultraviolet LED epitaxial wafer prepared by the present invention, in which the electroluminescence peak is about 352nm, the half-peak width is 22.2nm, and the current usage requirement level of the ultraviolet LED is reached, which shows that the ultraviolet LED device prepared in example 1 has excellent electrical properties.

Example 2

(1) selecting a substrate: adopting a Si (111) crystal orientation substrate;

(2) growth of AlN buffer layer 11: growing the AlN buffer layer 11 by adopting a magnetron sputtering Method (MS), wherein the growth temperature is 500 ℃, and the film thickness is 50nm to obtain the AlN buffer layer 11;

(3) epitaxial growth of the GaN buffer layer 12: the molecular beam epitaxial growth process is adopted, the substrate temperature is 600 ℃, and the pressure in the reaction chamber is 5.0 multiplied by 10^-5Growing a GaN buffer layer 12 with the thickness of 50nm on the AlN buffer layer 11 under the conditions that Pa, the value of the beam current ratio V/III is 40 and the growth speed is 0.8 ML/s;

(4) the AlGaN buffer layer 13 is epitaxially grown: etching the GaN buffer layer 12 by adopting ICP (inductively coupled plasma), and etching a trapezoidal stripe groove with the top width larger than the bottom width, the depth of the groove being 80nm, the top width of 200nm, the bottom width of 100nm and the interval of 200 nm; then, a metal organic chemical vapor deposition process is adopted, and the process conditions are as follows: the pressure of the reaction chamber is 300torr, the temperature of the Si substrate is 1060 ℃, the beam current ratio V/III is 5000, the growth rate is 4 mu m/h, and an AlGaN buffer layer 13 with the thickness of 500nm is grown on the GaN buffer layer 12;

(5) epitaxial growth of the undoped AlGaN layer 14: etching the GaN buffer layer 12 by adopting ICP (inductively coupled plasma), and etching trapezoidal stripe grooves with the top width larger than the bottom width, the depth of the grooves being 150nm, the top width of 200nm, the bottom width of 100nm and the interval of 200nm, wherein the etched trapezoidal grooves are not overlapped with the grooves etched in the step (4) in the vertical direction; then, a metal organic chemical vapor deposition process is adopted, and the process conditions are as follows: the pressure of the reaction chamber is 300torr, the temperature of the Si substrate is 1060 ℃, the beam current ratio V/III is 5000, the growth rate is 4 mu m/h, and the undoped AlGaN layer 14 with the thickness of 800nm is grown on the obtained GaN buffer layer 12;

(6) epitaxial growth of the n-type doped AlGaN layer 15: the metal organic chemical vapor deposition process is adopted, and the process conditions are as follows: growing an n-type doped AlGaN layer 15 with the thickness of 5 microns on the non-doped AlGaN layer 14 obtained in the step (5) under the conditions that the pressure of a reaction chamber is 300torr, the temperature of a Si substrate is 1060 ℃, the beam current ratio V/III is 3000, and the growth rate is 4 microns/h;

(7) epitaxial growth of AlGaN multiple quantum well layer 16: the metal organic chemical vapor deposition process is adopted, and the process conditions are as follows: growing an AlGaN multi-quantum well layer 16 on the n-type doped AlGaN layer 15 obtained in the step (6) under the conditions that the pressure of a reaction chamber is 300torr, the temperature of a Si substrate is 1060 ℃, the beam current ratio V/III is 5000 and the growth rate is 4 mu m/h; AlGaN MQW layer 16 is 10 periods of Al_0.1Ga_0.9N well layer/Al_0.25Ga_0.75N barrier layer of Al_0.1Ga_0.9Thickness of N well layer is 3nm, Al_0.25Ga_0.75The thickness of the N barrier layer is 13 nm;

(8) epitaxial growth of the electron blocking layer 17: the metal organic chemical vapor deposition process is adopted, and the process conditions are as follows: the pressure in the reaction chamber is 300torr, the Si substrate temperature is 1060 ℃, the beam current ratio V/III is 5000, the growth rate is 4 mu m/h, and Al with the thickness of 50nm is grown on the AlGaN multi-quantum well layer 16 obtained in the step (7)_0.15Ga_0.85An N electron blocking layer 17;

(10) epitaxial growth of p-type doped GaN thin film 18: the metal organic chemical vapor deposition process is adopted, and the process conditions are as follows: and (3) growing a p-type doped GaN film 18 with the thickness of 350nm on the electron blocking layer 17 obtained in the step (8) under the conditions that the pressure of the reaction chamber is 300torr, the temperature of the Si substrate is 1060 ℃, the beam current ratio V/III is 5000 and the growth rate is 4 mu m/h.

The test result of the ultraviolet LED epitaxial wafer grown on the Si substrate prepared in this example is similar to that of example 1, and is not repeated here.

The above embodiments are only preferred embodiments of the present invention, and the protection scope of the present invention cannot be limited thereby, and any insubstantial changes and substitutions made by those skilled in the art based on the present invention are all within the protection scope of the present invention.

Claims

1. An ultraviolet LED epitaxial wafer grown on a Si substrate is characterized by comprising an AlN buffer layer grown on the Si substrate, a GaN buffer layer grown on the AlN buffer layer, an AlGaN buffer layer grown on the GaN buffer layer, a non-doped AlGaN layer grown on the AlGaN buffer layer, an n-type doped AlGaN layer grown on the non-doped AlGaN layer, an AlGaN multi-quantum well layer grown on the n-type doped AlGaN layer, an electron blocking layer grown on the AlGaN multi-quantum well layer, and a p-type doped GaN thin film grown on the electron blocking layer;

2. The ultraviolet LED epitaxial wafer grown on a Si substrate according to claim 1, wherein the first trench is a first trapezoidal stripe trench having a top width larger than a bottom width, the depth of the first trapezoidal stripe trench is 50-80 nm, the top width is 100-200 nm, the bottom width is 50-100nm, and the interval is 100-200 nm.

3. The ultraviolet LED epitaxial wafer grown on a Si substrate according to claim 1, wherein the second trenches are second trapezoidal stripe trenches with a top width larger than a bottom width, the second trapezoidal stripe trenches have a depth of 100 to 150nm, a top width of 100 to 200nm, a bottom width of 50to 100nm, and an interval of 100 to 200 nm.

4. The ultraviolet LED epitaxial wafer grown on a Si substrate according to claim 1, wherein the Si substrate is a Si (111) crystal orientation substrate; the AlN buffer layer is 5-50 nm thick; the thickness of the GaN buffer layer is 100-300 nm; the thickness of the AlGaN buffer layer is 300-500 nm; the thickness of the non-doped AlGaN layer is 500-800 nm.

5. The ultraviolet LED epitaxial wafer grown on a Si substrate of claim 1, wherein the n-doped AlGaN layer is doped with Si with a Si doping concentration of 1 x 10¹⁷～1×10²⁰cm^-3The thickness of the n-type doped AlGaN layer is 3-5 μm.

6. The ultraviolet LED epitaxial wafer grown on a Si substrate according to claim 1, wherein the AlGaN multi-quantum well layer is 7-10 periods of Al_0.1Ga_0.9N well layer and Al_0.25Ga_0.75N barrier layer of Al_0.1Ga_0.9Thickness of N well layerDegree of 2 to 3nm, Al_0.25Ga_0.75The thickness of the N barrier layer is 10-13 nm.

7. The ultraviolet LED epitaxial wafer grown on a Si substrate of claim 1, wherein the electron blocking layer is Al_0.15Ga_0.85And the thickness of the electron blocking layer is 20-50 nm.

8. The ultraviolet LED epitaxial wafer grown on the Si substrate according to claim 1, wherein the thickness of the p-type doped GaN thin film is 300-350 nm.