Optical characterization of AlxGa1-xN alloys grown by MOCVD

AlxGa1-xN alloys with x varied from 0 to 0.35 have been produced on sapphir e substrates with GaN buffer layers by using: metalorganic chemical vapor d eposition (MOCVD), and the optical properties of the AlxGa1-xN alloys have been investigated using picosecond time-resolved photoluminescence (PL) spe ctroscopy at low temperature (10 K). Our results reveal that the PL intensi ty decreases with increasing of Al content. On the other hand, the PL decay lifetime increases with Al content. These results can be understood in ter ms of the effects of tail states in the density of slates (DOS) due to allo y fluctuation in the AlxGa1-xN alloys. The Al content dependence of the ene rgy tail-state distribution parameter, Eo, which is an important parameter for determining the optical and the electrical properties of the AlGaN allo ys, has been obtained experimentally.