Reduced residual stress and enhanced performance of GaN-based LEDs prepared by liquid phase deposition silicon oxide-nano patterned sapphire substrate

A simple liquid phase deposition (LPD) method was used to introduce nano SiO ₂ on sapphire substrates to fabricate nano-patterned sapphire substrates with top oxide layers (MNPSS). The X-ray diffraction (XRD) rocking curves and etching pit density (EPD) analyses show that the quality of MNPSS-GaN was better than that of GaN grown on flat sapphire substrates (FLAT-GaN). The photoluminescence (PL) spectrums showed a blueshift of MNPSS-GaN peak position compared with FLAT-GaN. The analyses of XRD reciprocal space map (RSM) revealed that this shift was caused by the residual stress.