Study on Deformations and Stress Distributions in Air-Bridged Lateral-Epitaxial-Grown GaN Films

• Published in: Japanese Journal of Applied Physics Vol. 42; no. Part 2, No. 10B; pp. L1248 - L1251
• Main Authors: Ishibashi, Akihiko, Sugahara, Gaku, Kawaguchi, Yasutoshi, Yokogawa, Toshiya
• Format: Journal Article
• Language: English
• Published: 15.10.2003
• ISSN: 0021-4922
• DOI: 10.1143/JJAP.42.L1248

2-D deformations and stress distributions in air-bridged lateral-epitaxial-grown GaN (ABLEG-GaN) films have been studied by AFM, 2-D finite element method (FEM) analysis, and micro-Raman spectroscopy. The ABLEG-GaN wings slightly tilt, and the direction of the wing tilt changes when the wings coalesce with each other. After coalescence of the wings, the tilt angle decreases with increasing film thickness. By FEM analysis and Raman spectroscopy, it has been revealed that the deformation of the wings originates from the distributions of thermal stress due to large mismatch of the thermal expansion in the GaN seed layer and in the sapphire substrate. The wing deformation is suppressed with increasing film thickness, since the stress distribution becomes more uniform. 17 refs.