Spectral shape analysis of ultraviolet luminescence in \textit{n}-type   ZnO:Ga
  Thin films of laser molecular-beam epitaxy grown \textit{n}-type Ga-doped ZnO were investigated with respect to their optical properties. Intense room-temperature photoluminescence (PL) in the near-band edge (NBE) region was observed. Moreover, its broadening of PL band was significantly larger than predicted by theoretical results modeled in terms of potential fluctuations caused by the random distribution of donor impurities. In addition, the lineshape was rather asymmetrical. To explain these features of the NBE bands, a vibronic model was developed accounting for contributions from a series of phonon replicas. 
T. Makino (Univ. Hyogo), Y. Segawa, S. Yoshida, A. Tsukazaki, A.   Ohtomo, M. Kawasaki, H. Koinuma