Lateral overgrowth of high quality GaN layers on GaN/Al 2O 3 patterned substrates by halide vapour-phase epitaxy

Abstract

The growth of GaN thick layers by halide vapour-phase epitaxy (HVPE) on metalorganic vapour-phase epitaxy (MOVPE)-GaN/Al 2O 3 substrates is reported. In a first step, we have shown that lateral overgrowth was enhanced following preferential crystallographic directions. Double crystal X-ray diffraction (DCXRD) assessment in ω scan showed full-width at half-maximum (FWHM) as small as 50 arcsec. On the way towards the realisation of self-supported GaN substrates, the present study was extended to epitaxial lateral overgrowth (ELOG) on large surface GaN/Al 2O 3 patterned substrates to achieve coalescence. Structural, electrical and optical characterisation of such layers was performed, underlining the promising quality of these materials.