Group III nitride crystal and manufacturing method thereof

Patent metadata

Field	Value
Publication number	US-9365948-B2
Application number	US-201213647194-A
Country	US
Kind code	B2
Filing date	Oct 8, 2012
Priority date	Nov 21, 2005
Publication date	Jun 14, 2016
Grant date	Jun 14, 2016

Abstract

A group III nitride crystal containing therein an alkali metal element comprises a base body, a first group III nitride crystal formed such that at least a part thereof makes a contact with the base body, the first group III nitride crystal deflecting threading dislocations in a direction different from a direction of crystal growth from the base body and a second nitride crystal formed adjacent to the first group III nitride crystal, the second nitride crystal having a crystal growth surface generally perpendicular to the direction of the crystal growth.

First claim

What is claimed is:

1. A GaN crystal, comprising:
a first GaN crystal formed over an underlying body such that at least a part of the first GaN crystal is in contact with the underlying body; and
a second GaN crystal in contact with the first GaN crytal, the second GaN crystal haying a surface formed of a c-surface,
wherein:
the first GaN crystal comprises a plurality of crystal regions (first domain) formed with an oblique facet, the plurality of crystal regions being free from Li or containing Li with a concentration lower than in the second GaN crystal;
the oblique facet forms a boundary between the first GaN crystal and the second GaN crystal;
threading dislocations propagating from the underlying body are deflected by the oblique facet in a direction perpendicular to a c-axis and are accumulated in a region where the second GaN crystal grown from adjacent first crystal domains meet with another second GaN crystal before the threading dislocations reach the c-surface of the second GaN crystal;
the second GaN crystal comprises a plurality of second domains bounded with threading dislocations reaching th c-surface;
a plurality of the second GaN crystal domains each extend in a c-axis direction;
surface threading dislocations are formed between adjacent second GaN crystal domains;
the second GaN crystal domains have a flat surface and comprise Li as an impurity with a concentration in the range of 10 15 -10 21 cm −3 ;
the surface threading dislocations are formed on the c-surface of the GaN crystal such that a dislocation density of the surface threating disclocations is lower than a dislocation density of threating dislocations formed in the CaN crystal as a whole; and
the c-surface of the second GaN crystal does not have a dimple surface.

2. The GaN crystal of claim 1 , wherein the surface threading dislocations are formed on the c-surface of the second GaN crystal with a dislocation density of about 10 4 cm −2 .

3. The GaN crystal of claim 1 , wherein the plurality of second domains are free from threading dislocations.

4. The GaN crystal of claim 1 , wherein the second domains are formed on the c-surface of the second GaN crystal in a stripe form.

5. The GaN crystal of claim 2 , wherein base threading dislocations of the GaN crystal have a dislocation density of 10 6 -10 10 cm −2 .

Assignees

• Iwata Hirokazu
• Sarayama Seiji
• Fuse Akihiro
• Ricoh Co Ltd

Inventors

• Iwata Hirokazu
• Sarayama Seiji
• Fuse Akihiro

Classifications

• H10P14/3456

  Polycrystalline · CPC title

• H10P14/3441

  Conductivity type · CPC title

• H10P14/3416

  Nitrides · CPC title

• H10P14/3216

  Nitrides · CPC title

• H10P14/2921

  being crystalline insulating materials · CPC title