The influence of high-temperature nitridation process on the crystalline quality of semipolar [formula omitted] GaN epitaxial films

Abstract

Semipolar (112‾2) GaN epitaxial films were grown on m-plane sapphire substrates by metal-organic chemical vapor deposition and additional high-temperature nitridation was introduced during the growth. The growth mechanism, surface microtopography, and the full width at half maximum (FWHM) of X-ray rocking curves (XRCs) of on-axis and off-axis (112‾2) GaN planes were investigated. The results demonstrate that additional high-temperature nitridation process could reduce surface roughness and anisotropy, and suppress the other orientations, and partially improve the crystalline quality of (112‾2) GaN epitaxial films. The XRCs FWHM of the off-axis (112‾2) GaN planes decrease and show a different varying tendency after additional high-temperature nitridation process associated with the partial dislocations and basal plane stacking faults (BSFs). The results of the modified Williamson-Hall (W–H) analysis and photoluminescence spectrum show the BSFs increased while the partial dislocations decreased after an additional high-temperature nitridation process. The improvement of crystalline quality was mainly correlated to the reduction of partial dislocations.