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CN-122002972-A - UVB epitaxial wafer and preparation method thereof

CN122002972ACN 122002972 ACN122002972 ACN 122002972ACN-122002972-A

Abstract

The invention discloses a UVB epitaxial wafer and a preparation method thereof, wherein the UVB epitaxial wafer comprises a substrate, a buffer layer, an AlN layer, an Al x Ga 1‑x N layer, a superlattice layer, an electrode contact layer, a multi-quantum well active layer, an electron blocking layer, a hole injection layer and a hole supply layer, wherein the buffer layer is arranged on the first surface of the substrate, the AlN layer is arranged on the buffer layer, the Al x Ga 1‑x N layer is composed of x, the superlattice layer comprises a stress release layer and a transition layer, each stress release layer comprises a plurality of periods, the thickness range of each period is 5-10 nm, the electrode contact layer, the multi-quantum well active layer, the electron blocking layer, the hole injection layer and the hole supply layer are sequentially stacked, the electron blocking layer, the hole injection layer and the hole supply layer cover a first area of the multi-quantum well active layer, a first electrode layer is arranged on a second area of the multi-quantum well active layer, and a second electrode layer is arranged on the hole supply layer. According to the invention, the half-wave width of the quantum well luminescence spectrum is reduced and the LED light maintenance rate is improved through the thin layer with gradually raised multiple growth components.

Inventors

  • XU GUANGYUAN
  • HOU JIE
  • ZHANG TONG
  • LI JINMIN

Assignees

  • 山西中科潞安紫外光电科技有限公司

Dates

Publication Date
20260508
Application Date
20241105

Claims (15)

  1. 1.A UVB epitaxial wafer, comprising: A substrate and a buffer layer on a first surface of the substrate; An AlN layer on the buffer layer; An Al x Ga 1-x N layer with the component x, wherein x is more than or equal to 0.8 and less than or equal to 0.9; The superlattice layer comprises a stress release layer and a transition layer, the stress release layer comprises a first stress release layer, a second stress release layer and a third stress release layer, each stress release layer comprises a plurality of periods, and the thickness range of each period is 5-10 nm; An electrode contact layer; The multi-quantum well active layer is of an L-shaped structure and comprises a first area and a second area, wherein the thickness of the first area is larger than that of the second area; An electron blocking layer, a hole injection layer and a hole supply layer which are stacked in sequence, wherein the electron blocking layer, the hole injection layer and the hole supply layer cover a first region of the multiple quantum well active layer; a first electrode layer on the second region of the multiple quantum well active layer; And a second electrode layer on the hole supply layer.
  2. 2. The UVB epitaxial wafer of claim 1, wherein the transition layer comprises a first transition layer and a second transition layer, the first transition layer being located between the first stress release layer and a second stress release layer, the second transition layer being located between the second stress release layer and a third stress release layer.
  3. 3. The UVB epitaxial wafer of claim 2, wherein the material of the first transition layer comprises Al x-0.1 Ga 1.1-x N having a composition of x-0.1 and the material of the second transition layer comprises Al x-0.2 Ga 1.2-x N having a composition of x-0.2.
  4. 4. The UVB epitaxial wafer of claim 1, wherein the first stress relief layer comprises n cycles, each cycle comprising 5 thin layers, each thin layer having a thickness in the range of 1-2 nm, wherein in the n cycle the 1 st component is x+0.005 x (n-1) -0.2, the 2 nd component is x+0.0025n-0.1525, the 3 rd component is x-0.1, the 4 th component is x-0.0025n-0.0475, and the 5 th component is x-0.005n+0.005.
  5. 5. The UVB epitaxial wafer of claim 1, wherein the first stress releasing layer is a graded composition layer comprising n cycles, each cycle having a thickness ranging from 5nm to 10nm, wherein in the nth cycle the composition is graded from x+0.005 x (n-1) -0.2 to x-0.005n+0.005.
  6. 6. The UVB epitaxial wafer of claim 1 wherein the second stress relief layer comprises n cycles each comprising 5 thin layers each having a thickness in the range of 1-2 nm, wherein in the n cycle the 1 st fraction is x+0.005 x (n-1) -0.3, the 2 nd fraction is x+0.0025n-0.2525, the 3 rd fraction is x-0.2, the 4 th fraction is x-0.0025n-0.1475, and the 5 th fraction is x-0.005n-0.095.
  7. 7. The UVB epitaxial wafer of claim 1 wherein the second stress relief layer is a graded composition layer comprising n cycles, each cycle having a thickness in the range of 5-10 nm, wherein in the nth cycle the composition is graded from x +0.005 x (n-1) -0.3 to x-0.005n-0.095.
  8. 8. The UVB epitaxial wafer of claim 1 wherein the third stress relief layer comprises n cycles each comprising 5 thin layers each having a thickness in the range of 1-2 nm, wherein in the nth cycle the 1 st fraction is x+0.005 x (n-1) -0.4, the 2 nd fraction is x+0.0025n-0.3525, the 3 rd fraction is x-0.3, the 4 th fraction is x-0.0025n-0.2475, and the 5 th fraction is x-0.005n-0.195.
  9. 9. The UVB epitaxial wafer of claim 1 wherein the third stress relief layer is a graded composition layer comprising n cycles, each cycle having a thickness in the range of 5-10 nm, wherein in the nth cycle the composition is graded from x +0.005 x (n-1) -0.4 to x-0.005n-0.195.
  10. 10. The UVB epitaxial wafer of claim 1, wherein the electrode contact layer comprises a nals x-0.3 Ga 1.3-x N having a composition of x-0.3.
  11. 11. The UVB epitaxial wafer of claim 1, wherein the Al x Ga 1-x N layer having a composition x has a thickness in the range of 50-200 nm, the first transition layer has a thickness in the range of 200-400 nm, the second transition layer has a thickness in the range of 200-400 nm, and the electrode contact layer has a thickness in the range of 200-1000 nm.
  12. 12. A method for preparing the UVB epitaxial wafer according to any one of claims 1 to 11, comprising the steps of: Providing a substrate, and forming a buffer layer on one side of the first surface of the substrate; forming an AlN layer on the surface of the buffer layer; forming an Al x Ga 1-x N layer with a composition of x on the AlN layer, wherein x is more than or equal to 0.8 and less than or equal to 0.9; Forming a first stress release layer on the surface of the Al x Ga 1-x N layer, wherein the first stress release layer comprises a plurality of periods, and the thickness range of each period is 5-10 nm; forming a first transition layer on the surface of the first stress release layer, wherein the first transition layer is Al x-0.1 Ga 1.1-x N; Forming a second stress release layer on the surface of the first transition layer, wherein the second stress release layer comprises a plurality of periods, and the thickness range of each period is 5-10 nm; Forming a second transition layer on the surface of the second stress release layer, wherein the second transition layer is Al x-0.2 Ga 1.2-x N; Forming a third stress release layer on the surface of the second transition layer, wherein the third stress release layer comprises a plurality of periods, and the thickness range of each period is 5-10 nm; Forming an electrode contact layer on the surface of the third stress release layer, wherein the electrode contact layer is nAL x-0.3 Ga 1.3-x N; Forming a multi-quantum well active layer on the electrode contact layer; Sequentially forming an electron blocking layer, a hole injection layer and a hole supply layer on the multi-quantum well active layer; Etching part of the hole supply layer, the hole injection layer, the electron blocking layer and the multi-quantum well active layer until the second area of the electrode contact layer is exposed; forming a first electrode layer on the second region of the electrode contact layer; And forming a second electrode layer on the hole supply layer.
  13. 13. The method for preparing a UVB epitaxial wafer according to claim 12, wherein the step of forming the buffer layer on the first surface side of the substrate comprises the steps of forming the buffer layer through a magnetron sputtering growth process, wherein the magnetron sputtering growth process conditions comprise a temperature range of 550-700 ℃, a sputtering power range of 1000-4000W, a nitrogen flow range of 80-200 sccm, an oxygen flow range of 0.5-5 sccm, an argon flow range of 0.1-40 sccm and a deposition time range of 16 s-100 s.
  14. 14. The method for preparing a UVB epitaxial wafer of claim 12, wherein forming an AlN layer on the surface of the buffer layer comprises the steps of: Forming an AlN 3D layer on the buffer layer by adopting a vapor phase epitaxial growth process; and forming an AlN 2D layer on the buffer layer by adopting a vapor phase epitaxial growth process.
  15. 15. The method of manufacturing a UVB epitaxial wafer of claim 12, wherein etching the portion of the hole-supplying layer, the hole-injecting layer, the electron-blocking layer, and the multiple quantum well active layer comprises the steps of: And etching part of the hole supply layer, the hole injection layer, the electron blocking layer and the multi-quantum well active layer by using an ICP etching process.

Description

UVB epitaxial wafer and preparation method thereof Technical Field The application relates to the field of ultraviolet LED epitaxial wafer manufacturing, in particular to a UVB epitaxial wafer and a preparation method thereof. Background In the technical field of medical treatment, the UVB phototherapy technology utilizes 280-315nm light of UVB wave band to treat various skin diseases, such as psoriasis, eczema, pruritus, vitiligo, lichen planus, granuloma and the like. There are three main types of UVB phototherapy methods currently used for dermatological conditions (1) broad spectrum UVB treatment with UVB radiation at 280-315nm, wavelengths below 300nm, which can cause erythema or severe burning and increase the risk of skin cancer, and (2) narrow spectrum UVB treatment with 311nmUVB, which is narrower and stronger in wavelength. This is the most common phototherapy method used today. The narrow spectrum UVB is produced by special fluorescent tubes, aimed at producing UVB light of very narrow wavelength, 311nm has proven to be very effective and safe in inhibiting skin inflammation. It is now the most widely used form of phototherapy and (3) 308nm excimer laser, which effectively targets the affected skin for treatment without overexposure of other areas. The treatment effect is better than other traditional phototherapy. The UVB spectrum generated by the fluorescent tube has the advantages of narrow half-width (< 5 nm), but low irradiance, slower onset of action and long treatment course when treating skin diseases. Meanwhile, the light source has large volume, needs high-voltage driving and has the service life of only 1000-3000 hours. The UVB spectrum generated by the 308nm excimer laser has the advantages of narrow half-width (< 5 nm), high irradiance and quicker effect in treating skin diseases. High-voltage driving is also required, and the service life is short, which is only 200-600 hours. The half-peak width of the spectrum generated by the UVB LED is larger, generally 12-15 nm, and the typical half-peak width is about 13.5 nm. The irradiance of the UVB can be accurately regulated by regulating the current, meanwhile, the volume of the UVB LED is smaller, a portable phototherapy instrument can be manufactured, the driving voltage of the UVB LED is lower, and the driving voltage of a single LED is 5-7V. The service life of the light source is longer than 10000 hours. The UVB LED is therefore used with a bandpass filter added to the front end, which approximately loses 40% of the UVB light. The aluminum nitride template is a substrate material for epitaxial growth of the aluminum gallium nitride-based deep ultraviolet LED, the crystallization quality of the template directly determines the crystal quality of aluminum gallium nitride on the upper layer, the AlGaN-based material grows on the surface of the AlN template to be a heterogeneous material for epitaxial growth, lattice mismatch exists between the aluminum nitride template and the AlGaN-based material, the size of the lattice mismatch is related to the difference between the material components, and the larger the component difference is, the larger the lattice mismatch is. Therefore, for a certain composition of Al xGa1-x N (x < 1), the lattice constant is larger than that of AlN, and the larger the lattice mismatch between the two is determined by the composition x, the larger the lattice mismatch between Al xGa1-x N and AlN is, and the poorer the morphology and crystal quality of Al xGa1-x N grown on the surface of an AlN template are. At present, two methods for adjusting stress are commonly used, namely, a transition layer with gradually reduced components is grown, the transition of lattice constants is realized through component gradual change, but the transition by using a single component Al xGa1-x N layer cannot reduce the lattice mismatch between an AlN layer and a lower component nAL xGa1-x N layer, dislocation can be extended to a quantum well layer, so that the non-radiative composite efficiency is reduced, and meanwhile, an AlN template layer with small lattice constants can generate larger compressive stress on the nAL xGa1-x N layer with larger lattice constants, so that the half-wave width of a quantum well luminescence spectrum is widened. Another is to grow an AlN/AlGaN superlattice layer between an AlN template and n-type AlGaN, which is relatively common, and to filter dislocations through the superlattice while achieving stress relief, but the nAlGaN layer in the UVB structure has a lower composition and a larger mismatch with AlN, and the use of an AlN/AlGaN superlattice layer requires an increase in the composition differences of the AlN and AlGaN layers, which is more demanding for growth conditions, thereby reducing process repeatability. Disclosure of Invention In order to solve the problems in the prior art, the invention provides a UVB epitaxial wafer and a preparation method thereof. The invention provides a