Selective area metalorganic vapor phase epitaxy of thick crack-free GaN films on trenched SiC substrates

Abstract

Crack-free GaN films up to 11-μm-thick have been grown by using trenched SiC substrates and selective area metalorganic vapor phase epitaxy. These crack-free GaN films have hexagonal shapes and are surrounded by trenches. 97% of the hexagonal GaN films with side lengths of 100 μm and thickness of 11 μm was crack-free. The GaN films do not crack because the lateral propagation of cracks stops at the trenches and strain is relaxed in the small-area hexagonal GaN. This strain relaxation is confirmed by micro-Raman scattering measurements and agrees well with theoretical predictions.