Optical and electrical properties of Al-rich AlGaN alloys

AlxGa1-xN alloys with x up to 0.7 were grown by metalorganic chemical vapor deposition and their optical properties were investigated by deep UV time- resolved photoluminescence (PL) spectroscopy. Our results revealed that bot h the activation energy of the PL emission intensity and the PL decay lifet ime exhibit sharp increases at x of around 0.4. The results can be understo od in terms of the sharp increase of the impurity binding energy or the car rier/exciton localization energy around x=0.4. A three orders of magnitude increase in resistivity of undoped AlGaN alloys at x of around 0.4 was also observed, which further corroborated the optical results. (C) 2001 America n Institute of Physics.