Effects of interface roughness on photoluminescence full width at half maximum in GaN/AlGaN quantum wells

Low temperature photoluminescence (PL) measurements have been performed for a set of GaN/Al_xGa_1-xN quantum wells (QWs). The experimental results show that the optical full width at half maximum (FWHM) increases relatively rapidly with increasing Al composition in the Al_xGa_1-xN barrier, and increases only slightly with increasing GaN well width. A model considering the interface roughness is used to interpret the experimental results. In the model, the FWHM's broadening caused by the interface roughness is calculated based on the triangle potential well approximation. We find that the calculated results accord with the experimental results well.