The peculiarities of current-illumination characteristic and the photoconductivity kinetics in sillenite-type crystals

Abstract The present paper deals with studying the current-illumination characteristics, the temperature dependence and the kinetics of photoconductivity in sillenite-type crystals, Bi12XO20 (where × = Si, Ge, Ti). The peculiarities of relaxation and steady-state photoconductivity are shown to be similar both for the intrinsic (hv>3 eV) and the impurity blue-green light (3 eV>hv>2 eV). A switching to a more photosensitive state (with the multiplicity up to 10−3 times) retaining with a reverse decrease of light intensity has been observed in current-illumination characteristics. The reduction of the initial photosensitive state is possible only after the heating process or IR-radiation. At low temperatures (T = 250 K) an exponential increase of photocurrent and sublinear current-illumination characteristics are observed (with degree of 0.5). The photocurrent kinetics is characterized by continuous increase of instantaneous time of relaxation. With a long-term illumination one can observe a gradual, “S”-typ...