Group III nitride crystal and manufacturing method thereof

摘要

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.

主权项

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 1015-1021 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.