Stress Relaxation in Porous GaN Prepared by UV Assisted Electrochemical Etching

Abstract

This study describes the stress relaxation in porous GaN grown on Al2O3 substrates. The results indicate that the stress relaxation has taken place in the samples which increases by increasing the etching current. As compared to the as-grown GaN films, porous GaN exhibits substantial photoluminescence (PL) intensity enhancement with red-shifted band-edge peaks associated with the relaxation of the compressive stress. The red shifted phonon energy peak (E2) in the Raman spectra of the porous GaN films confirms further such a stress relaxation. Scanning electron microscopy (SEM) demonstrates that, the current density has significant effect on the size and shape of the pores.