AlGaN/GaN multiple quantum wells grown on facet-controlled epitaxial lateral overgrown GaN/sapphire templates

摘要

Epitaxial lateral overgrowth of GaN with (11 (2) over bar2) facets was realized by metal organic chemical vapour deposition on GaN/ sapphire (0001) substrates with an SiO2 stripe mask. After wet etching of the mask, periodic AlGaN/ GaN multiple quantum wells (MQWs) were grown on the whole surface. Cross section transmission electron microscopy showed that the average growth rate on the (11 (2) over bar2) facet is lower than on the (0001) plane. The concentration of Al of AlGaN/GaN MQWs was higher on the (0001) facet than on the (11 (2) over bar2) surface, as measured by secondary ion mass spectrometry and high resolution x- ray diffraction (HR-XRD). Micro- Raman scattering spectroscopy revealed a significant relaxation of compressive stress in the laterally overgrown GaN. Micro- photoluminescence spectra confirmed quantum confinement of electrons in MQWs. The achieved optical quality of MQWs on the (11 (2) over bar2) facet is comparable with that on the (0001) plane.