Kunzer, MichaelMichaelKunzerKaufmann, U.U.KaufmannMaier, M.M.MaierObloh, H.H.Obloh2022-03-092022-03-091998https://publica.fraunhofer.de/handle/publica/330435Recombination paths in GaN/Al(x)Ga(1-x)N (x<0 18) heterostructures on sapphire were studied by temperature and excitation power density dependent photoluminescence. Free and bound AlGaN excitons are identified. A spatially indirect, below band gap emission line shows a strong red shift with increasing Al content. The data provide evidence, that this red shift is caused by a piezoelectric field which forms a two-dimensional electron gas at the GaN/AlGaN interface.enAlGaNphotoluminescencePhotolumineszenzPL621667conference paper