Growth of GaN on (1 1 1) Si: a route towards self-supported GaN

Abstract

Crack-free GaN/Si(1 1 1) thin layers (0.5 μm) were grown by metal organic vapour phase epitaxy, using either an AlN buffer layer or (AlN/GaN) strained superlattices. High-resolution X-ray diffraction exhibited a full-width at half-maximum as low as 630 arcsec for rocking curve scan on (0 0 0 2) line. Low temperature PL spectra of GaN/Si(1 1 1) show unambiguously a state of tensile biaxial strain for all of the layers. These GaN layers were then lifted-off by wet chemical etching from their original silicon substrate and Van der Waals bonded on sapphire or quartz substrates. The ability of growing thick GaN (15–100 μm) by halide vapour phase epitaxy on such templates has been successfully achieved, marking a step towards self-supported GaN substrates.