Group III-V nitride-based semiconductor substrate and method of fabricating the same

Abstract

A group III-V nitride-based semiconductor substrate has: a first layer made of GaN single crystal; and a second layer formed on the first layer, the second layer made of group III-V nitride-based semiconductor single crystal represented by AlxGa1-xN, where 0

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The preferred embodiments according to the invention will be explained below referring to the drawings, wherein:

FIG. 1 is a cross sectional view showing a composite self-standing substrate in a preferred embodiment according to the invention;

FIG. 2 is a schematic diagram showing an HVPE reactor to be used in the preferred embodiments of the invention;

FIGS. 3A to 3F are schematic cross sectional views showing a method of making a composite self-standing substrate in Example 1 according to the invention;

FIG. 4 is a schematic cross sectional view showing an LED epitaxial layer in Example 2 according to the invention;

FIG. 5 is a schematic cross sectional view showing an LED epitaxial layer in Comparative Example; and

FIGS. 6A to 6F are schematic cross sectional views showing a method of making a composite self-standing substrate in Example 3 according to the invention;

Claims

1. A group III-V nitride-based semiconductor substrate, comprising: a first layer comprising GaN single crystal; anda second layer formed on the first layer, the second layer comprising group III-V nitride-based semiconductor single crystal represented by AlxGa1-xN, where 0<x≦1,wherein a top surface and a back surface of the substrate are flattened.

2. The group III-V nitride-based semiconductor substrate according to claim 1: the second layer comprises the group III-V nitride-based semiconductor single crystal represented by AlxGa1-xN, where 0<x≦1, whose Al ratio increasing continuously from an interface of the first layer and the second layer.

3. The group III-V nitride-based semiconductor substrate according to claim 1, wherein: the substrate is in circular form with a diameter of not less than 50 mm and a thickness of not less than 200 μm.

4. The group III-V nitride-based semiconductor substrate according to claim 1, wherein: the substrate comprises a dislocation density of not more than 1×108 cm−2 on its surface.

5. The group III-V nitride-based semiconductor substrate according to claim 1, wherein: the AlxGa1-xN layer, where 0<x≦1, comprises a thickness of not less than 100 nm.

6. The group III-V nitride-based semiconductor substrate according to claim 1, wherein: the AlxGa1-xN layer, where 0<x≦1, comprises a thickness of not less than 100 nm and not more than 100 μm.

7. A method of making a group III-V nitride-based semiconductor substrate, comprising the steps of: growing a group III-V nitride-based semiconductor film on a hetero-substrate and then depositing a metal film thereon;heating the hetero-substrate with the metal film in an atmosphere containing hydrogen gas or hydride gas to form a void in the group III-V nitride-based semiconductor film;growing a first layer comprising a GaN single crystal thereon;further growing thereon a second layer comprising a group III-V nitride-based semiconductor single crystal represented by AlxGa1-xN, where 0<x≦1;removing the hetero-substrate while leaving the first layer and the second layer to provide the group III-V nitride-based semiconductor substrate; andflattening a top surface and a back surface of the substrate.

8. The method according to claim 7, wherein: the first layer and the second layer are continuously grown in a same reactor.

9. The method according to claim 7, wherein: the first layer and the second layer are grown by HVPE.