An In-defect complex as a possible explanation for high luminous efficacy of InGaN and AlInN based devices

The role of indium in GaN and AlN films is investigated with the method of the perturbed angular correlation (PAC). Using the PAC probe $^{111}$In in addition to indium on substitutional cation sites a large fraction of probes is found in a distinctly different microscopic environment which was attributed to the formation of an indium nitrogen-vacancy (VN) complex. The influence of an electron capture induced after ef fect is ruled out by additional measurements with the PAC probes $^{111m}$Cd and $^{117}$Cd and using GaN with different dopants. It is shown that the VN is not bound to substitutional Cd impurities suggesting that the In-VN complex formation is a particularity of In in GaN and AlN. Finally, a preliminary model is presented to explain the temperature behavior of the electric field gradient, observed in the In-VN complex measured with $^{111}$In.