Columnar Structures and Stress Relaxation in Thick GaN Films Grown on Sapphire by HVPE

• 来源期刊: 中国物理快报（英文版）
• 年，卷（期）: 2007,（3）
• 页码范围: 822-824
• 页数: 3页
• 语种: 英文

摘要

Thick GaN films with high quality are directly grown on sapphire in a home-built vertical hydride vapour phase epitaxy (HVPE) reactor. The optical and structural properties of large scale columnar domains near the interface are studied using cathodoluminescence and micro-Raman scattering. These columnar domains show a strong emission intensity due to extremely high free carrier concentration up to 2 × 1019 cm-3, which are related with impurities trapped in structural defects. The compressive stress in GaN film clearly decreases with increasing distance from interface. The quasi-continuous columnar domains play an important role in the stress relaxation for the upper high quality layer.