Photoluminescence of wet- and dry-etched gallium nitride

The photoluminescence (PL) of GaN grown on SiC is studied as a function of etch depth for two types of etches, photoelectrochemical and chemically assisted ion beam. It is found that as the etch proceeds deeper toward the substrate, the PL exhibits an increasing blue-shift and an increase in emission intensity of the donor acceptor pair band, which indicates increasing biaxial compressive stress and increasing impurity concentration near the substrate. The PL spectra of the dry etched GaN tended to have slightly higher intensities than comparably wet etched GaN.