Group III-V nitride-based semiconductor substrate, group III-V nitride-based device 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 0.9

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 cross sectional view showing a composite self-standing substrate in another preferred embodiment according to the invention;

FIG. 3 is a schematic diagram showing an HVPE reactor to be used in the preferred embodiments of the invention;

FIGS. 4A to 4F are schematic cross sectional views showing a method of making a composite self-standing substrate in Example 1 according to the invention;

FIGS. 5A to 5F are schematic cross sectional views showing a method of making a composite self-standing substrate in Example 2 according to the invention;

FIG. 6 is a schematic cross sectional view showing an LED in Example 3 according to the invention; and

FIG. 7 is a schematic cross sectional view showing an LED in Comparative Example.

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 0.9<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, further comprising: a transition layer formed between the first layer and the second layer, the transition layer comprising a composition that changes continuously from GaN to AlxGa1-xN, where 0.9<x≦1.

3. The group III-V nitride-based semiconductor substrate according to claim 1, wherein: the substrate is in circular form with a diameter of 50 mm or more and a thickness of 200 μm or more.

4. The group III-V nitride-based semiconductor substrate according to claim 1, wherein: the substrate comprises a dislocation density of 1×108 cm−2 or less on its surface.

5. The group III-V nitride-based semiconductor substrate according to claim 1, wherein: the second layer comprises a thickness of 50 μm or more.

6. The group III-V nitride-based semiconductor substrate according to claim 1, wherein: the substrate comprises a self-standing substrate.

7. A group III-V nitride-based device, comprising: a layer comprising a group III-V nitride-based semiconductor single crystal represented by AlxGa1-xN, where 0.9<x≦1, the crystal comprising a dislocation density of 1×108 cm−2 or less; anda device structure formed on the layer,wherein the device structure comprises a group III-V nitride-based semiconductor single crystal represented by InyGazAl1-y-zN, where 0≦y≦1, 0≦z≦1 and 0≦y+z≦1.

8. 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 0.9<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.

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

10. The method according to claim 8, wherein: the first layer and the second layer are grown by HVPE.

11. A method of making a group III-V nitride-based device, comprising the steps of: forming a device structure comprising an epitaxial growth layer on the group III-V nitride-based semiconductor substrate as defined in claim 1; andflattening a back surface of the substrate to remove the first layer to render the second layer exposed,wherein the group III-V nitride-based device is formed such that the device structure is formed on the second layer.