Epitaxial structure

Patent metadata

Field	Value
Publication number	US-2021336011-A1
Application number	US-202117238311-A
Country	US
Kind code	A1
Filing date	Apr 23, 2021
Priority date	Apr 24, 2020
Publication date	Oct 28, 2021
Grant date	—

Abstract

An epitaxial structure includes a substrate, a buffer layer, a channel layer, a barrier layer, a diffusion barrier layer, and a P-type gallium nitride layer sequentially stacked from bottom to top. The P-type gallium nitride layer has a first lattice constant. The diffusion barrier layer includes a chemical composition of Inx1Aly1Gaz1N, where x1+y1+z1=1, 0≤x1≤0.3, 0≤y1≤1.0, and 0≤z1≤1.0. The chemical composition of the diffusion barrier layer has a proportional relationship so that the diffusion barrier layer has a second lattice constant that matches the first lattice constant, and the second lattice constant is between 80% and 120% of the first lattice constant.

First claim

What is claimed is:

1 . An epitaxial structure, comprising:
a substrate; a buffer layer disposed on the substrate; a channel layer disposed on the buffer layer; a barrier layer disposed on the channel layer; and a P-type gallium nitride layer disposed on the barrier layer, and the P-type gallium nitride layer having a first lattice constant; wherein the epitaxial structure further comprises a diffusion barrier layer disposed between the barrier layer and the P-type gallium nitride layer, the diffusion barrier layer includes a chemical composition of In x1 Al y1 Ga z1 N, where x1+y1+z1=1, 0≤x1≤0.3, 0≤y1≤1.0, and 0≤z1≤1.0; wherein the chemical composition of the diffusion barrier layer has a proportional relationship, so that the diffusion barrier layer has a second lattice constant that matches the first lattice constant, and the second lattice constant is between 80% and 120% of the first lattice constant.

2 . The epitaxial structure according to claim 1 , wherein the first lattice constant of the P-type gallium nitride layer is 3.2±0.3 Å, and the second lattice constant of the diffusion barrier layer is 3.2±0.3 Å.

3 . The epitaxial structure according to claim 1 , wherein, in the diffusion barrier layer, the proportional relationship of the chemical composition is: y1 and x1 satisfy the following relationship: y1=k1*x1, where 2≤k1≤8; and y1 and z1 satisfy the following relationship: y1*z1=k2, where 0.05≤k2≤0.3.

4 . The epitaxial structure according to claim 1 , wherein the barrier layer includes a chemical composition of Al y2 Ga z2 N, where y2+z2=1, 0.1≤y2≤0.3, and 0≤z2≤1; wherein the aluminum (Al) content y2 of the barrier layer is between 0.1 and 0.3, and a maximum value of the aluminum (Al) content y1 of the diffusion barrier layer is not less than 0.4.

5 . The epitaxial structure according to claim 4 , wherein, in the diffusion barrier layer, the maximum value of the aluminum (Al) content enables a maximum energy gap of the diffusion barrier layer to be not less than 4.6 eV.

6 . The epitaxial structure according to claim 1 , wherein, in the diffusion barrier layer, the aluminum (Al) content, the indium (In) content and the gallium (Ga) content are all fixed values; wherein the aluminum (Al) content is between 40% and 100%, the indium (In) content is between 0% and 30%, and the gallium (Ga) content is between 0% and 30%; wherein the diffusion barrier layer is a single-layer structure, and a total thickness of the diffusion barrier layer is between 1 nanometer and 10 nanometers.

7 . The epitaxial structure according to claim 6 , wherein the second lattice constant of the diffusion barrier layer is 3.2±0.3 Å, and an energy gap of the diffusion barrier layer is 4.8±0.2 eV.

8 . The epitaxial structure according to claim 1 , wherein, in the diffusion barrier layer, the aluminum (Al) content is decreased in a stepwise manner, a gradual manner, a stepwise and gradual interlacing manner, or a high and low oscillation manner, along a thickness growth direction of the diffusion barrier layer; wherein an initial content of the aluminum (Al) content along the thickness growth direction is between 60% and 80%, and a final content of the aluminum (Al) content along the thickness growth direction is between 0% and 20%; wherein the indium (In) content is decreased in a stepwise manner, a gradual manner, a stepwise and gradual interlacing manner, or a high and low oscillation manner, along the thickness growth direction of the diffusion barrier layer; wherein an initial content of the indium (In) content along the thickness growth direction is between 10% and 25%, and a final content of the indium (In) content along the thickness growth direction is between 0% and 10%; wherein the gallium (Ga) content is increased in a stepwise manner, a gradual manner, a stepwise and gradual interlacing manner, or a high and low oscillation manner, along the thickness growth direction of the diffusion barrier layer; wherein an initial content of the gallium (Ga) content along the thickness growth direction is between 10% and 30%, and a final content of the gallium (Ga) content along the thickness growth direction is between 80% and 100%; wherein the diffusion barrier layer is a single-layer structure or a multi-layer structure, and a total thickness of the diffusion barrier layer is between 2 nanometers and 10 nanometers.

9 . The epitaxial structure according to claim 8 , wherein an energy gap of the diffusion barrier layer is decreased in a stepwise manner, a gradual manner, a stepwise and gradual interlacing manner, or a high and low oscillation manner, along the thickness growth direction of the diffusion barrier layer; wherein the second lattice constant of the diffusion barrier layer is 3.2±0.3 Å, an initial energy gap of the diffusion barrier layer along the thickness growth direction is 5.0±0.2 eV, and an final energy gap of the diffusion barrier layer along the thickness growth direction is 3.5±0.2 eV.

10 . The epitaxial structure according to claim 1 , wherein the P-type gallium nitride layer includes an acceptor doping element with a doping concentration greater than 1×10 18 atoms per cubic centimeter; wherein the acceptor doping element is at least one material selected from a group consisting of magnesium (Mg), carbon (C), calcium (Ca), iron (Fe), chromium (Cr), vanadium (V), manganese (Mn), and beryllium (Be).

Assignees

• Globalwafers Co Ltd

Inventors

• Lin Tzu-Yao
• Liu Jia-Zhe
• Shih Ying-Ru

Classifications

• H10P14/3444

  P-type · CPC title

• H10P14/3446

  Transition metal elements; Rare earth elements · CPC title

• H10P14/3416

  Nitrides · CPC title

• H10P14/3251

  consisting of three or more layers · CPC title

• H10P14/3254

  Graded layers · CPC title