Nitride semiconductor device and quantum cascade laser using the same

Patent metadata

Field	Value
Publication number	US-10038306-B2
Application number	US-201615378089-A
Country	US
Kind code	B2
Filing date	Dec 14, 2016
Priority date	Jan 13, 2016
Publication date	Jul 31, 2018
Grant date	Jul 31, 2018

Abstract

A nitride semiconductor device includes a GaN substrate in which an angle between a principal surface and an m-plane of GaN is −5° or more and +5° or less, a first intermediate layer disposed on the principal surface of the substrate and made of Al z Ga (1−z) N, 0≤z≤1, and a second intermediate layer disposed on a principal surface of the first intermediate layer, having an Al content different from that of the first intermediate layer, and made of Al x1 In y1 Ga (1−x1−y1) N, 0≤x1≤1, 0≤y1≤1. A quantum cascade laser includes the nitride semiconductor device.

First claim

What is claimed is:

1. A nitride semiconductor device comprising:
a GaN substrate in which an angle between a principal surface and an m-plane of GaN is −5° or more and +5° or less;
a first intermediate layer disposed on the principal surface of the substrate and made of Al z Ga (1−z) N, 0≤z≤1;
a second intermediate layer disposed on a principal surface of the first intermediate layer, having an Al content different from that of the first intermediate layer, and made of Al x1 In y1 Ga (1−x1−y1) N, 0≤x1≤1, 0≤y1≤1;
an active layer that includes a quantum well layer and a barrier layer and is disposed on the second intermediate layer on a side opposite to the substrate; wherein
a percentage difference between a c-axis lattice constant or an a-axis lattice constant of the barrier layer and a c-axis lattice constant or an a-axis lattice constant of the second intermediate layer is 0.3% or less.

2. The nitride semiconductor device according to claim 1 , wherein the first intermediate layer has a higher Al content than the second intermediate layer.

3. The nitride semiconductor device according to claim 1 , wherein the first intermediate layer is an AlN layer.

4. The nitride semiconductor device according to claim 1 , wherein the first intermediate layer has a smaller thickness than the second intermediate layer.

5. The nitride semiconductor device according to claim 4 , wherein the first intermediate layer has a thickness of 100 nm or less.

6. The nitride semiconductor device according to claim 5 , wherein the first intermediate layer has a thickness of 5 nm or more and 40 nm or less.

7. The nitride semiconductor device according to claim 1 , wherein the Al content of the first intermediate layer increases in a gradient manner as a distance between the first intermediate layer and the substrate increases, and the second intermediate layer has a substantially constant Al content.

8. The nitride semiconductor device according to claim 7 , wherein an Al content in a portion of the first intermediate layer on the substrate side is 0 or more and 0.05 or less.

9. The nitride semiconductor device according to claim 7 , wherein a percentage difference between an Al content in a portion of the first intermediate layer on a side opposite to the substrate and the Al content of the second intermediate layer is ±1%.

10. The nitride semiconductor device according to claim 7 , wherein the first intermediate layer has a thickness of 1 μm or more.

11. The nitride semiconductor device according to claim 1 ,
wherein the active layer includes one or more of the quantum well layers and one or more of the barrier layers, and
a percentage difference between an average lattice constant of the active layer and the c-axis lattice constant or the a-axis lattice constant of the second intermediate layer is 0.3% or less, the average lattice constant being calculated from: a total thickness of the quantum well layers×a c-axis lattice constant or an a-axis lattice constant of the quantum well layers+a total thickness of the barrier layers×a c-axis lattice constant or an a-axis lattice constant of the barrier layers/a total thickness of the quantum well layers and the barrier layers.

12. The nitride semiconductor device according to claim 1 , wherein a percentage difference between an a-axis lattice constant or a c-axis lattice constant in a portion of the first intermediate layer on a side opposite to the substrate and an average lattice constant calculated by dividing a total of thickness×c-axis lattice constant or a-axis lattice constant of all layers stacked on the second intermediate layer on a side opposite to the substrate by a total thickness of all the layers stacked on the second intermediate layer on the side opposite to the substrate is 0.3% or less.

13. A quantum cascade laser comprising the nitride semiconductor device according to claim 1 .

Assignees

• Sharp Kk
• Univ Tokyo

Inventors

• Kotani Teruhisa
• Arakawa Yasuhiko

Classifications

• H01S5/32025

  non-polar orientation · CPC title

• H01S5/3422

  comprising type-II quantum wells or superlattices · CPC title

• H01S2301/173

  The laser chip comprising special buffer layers, e.g. dislocation prevention or reduction · CPC title

• H01S5/34333

  with a well layer based on Ga(In)N or Ga(In)P, e.g. blue laser · CPC title

• H01S5/3407

  characterised by special barrier layers · CPC title