Time-resolved photoluminescence studies of AlxGa1-xN alloys

The optical properties of AlxGa1-xN alloys with x varied from 0 to 0.35 hav e been investigated by picosecond time-resolved photoluminescence (PL) spec troscopy. Our results revealed that while the PL intensity decreases with a n increase of Al content, the low-temperature PL decay lifetime increases w ith Al content. These results can be understood in terms of the effects of tail states in the density of states due to alloy fluctuation in the AlxGa1 -xN alloys. The Al-content dependence of the energy-tail-state distribution parameter E-0, which is an important parameter for determining optical and electrical properties of the AlGaN alloys, has been obtained experimentall y. The PL decay lifetime increases with the localization energy and, conseq uently, increases with Al content. The implications of our findings to III- nitride optoelectronic device applications are also discussed. (C) 2000 Ame rican Institute of Physics. [S0003-6951(00)01310-3].