Light-induced processes in a-Si:H films at elevated temperatures

At temperatures T>120 °C the kinetics of the dark conductivity (σ _d) of undoped and borondoped a-Si:H films during and after the cessation of illumination is observed to be nonmonotonic, with fast and slow processes of variation of σ _d of opposite sign. A fast or slow σ _d relaxation process described by a stretched exponential function can be isolated by varying the duration and intensity of illumination or the film temperature. The nonmonotonic relaxation of σ _d is described by a sum of two stretched exponentials, whose parameters τ and β depend on the film characteristics and on the temperature, exposure time, and intensity of illumination. The nature of the nonmonotonic relaxation is discussed. Fiz. Tekh. Poluprovodn. 31, 1455–1459 (December 1997)