High quality ELO-GaN layers on GaN/Al2O3 patterned substrates by halide vapour phase epitaxy

The growth of thick GaN layers by halide vapour phase epitaxy (HVPE) on patterned metal organics vapour phase epitaxy (MOVPE)-GaN/Al2O3 substrates and their characterisation is reported. The growth on small area features has shown that lateral overgrowth was enhanced following preferential crystallographic directions. Double crystal X-ray diffraction (DCXRD) assessment in ω scan showed 50 arcsec full width at half maximum (FWHM) for layers grown on a small area hexagonal holes field. On the way towards the realisation of self-supported GaN substrates, the present study was extended to epitaxial lateral overgrowth (ELO) on large surface GaN/Al2O3 patterned substrates to achieve full coalescence. Hexagonal holes and parallel stripes features were used. Structural, electrical and optical characterisation of such layers was performed, underlining the promising quality of these materials.