Temperature, intensity, and field dependence of the absorption coefficient of Bi(12)SiO(20)

Department of Applied Physics, Stanford University, Stanford, California 94305We report the observation of incident intensity and applied-field-induced increases in the absorption coefficient of Bi(12)SiO(20) at 514.5 nm. Absorption changes as large as 50% have been observed, but 10% is more typical. The main effect is thermal shifting of the absorption edge caused by ohmic heating from the photocurrent: Deltaalpha(T) = 0.0083 cm(-1) K(-1). In addition, there is a small absorption change proportional to the intensity alone that is approximately given by Deltaalpha(I) = 0.03 ln(I). We also report a linear decrease in the photoconductivity with temperature for T in the range 295-330 K.