Growth of GaN on (111) Si:: a route towards self-supported GaN

Crack-free GaN/Si(1 1 1) thin layers (0.5 mum) were grown by metal organic vapour phase epitaxy, using either an AIN 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(I 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 (115-100 mum) by halide vapour phase epitaxy on such templates has been successfully achieved., marking a step towards self-supported GaN substrates. (C) 2001 Elsevier Science B.V. All rights reserved.