Persistent photoconductivity in SiGe/Si quantum wells

Abstract

Persistent photoconductivity (PPC) has been observed in boron-doped Si1-xGex/Si quantum wells. The decay kinetics of the PPC effect can be well described by a stretched-exponential function, I-ppc(t) = I-ppc(0)exp[-(t/tau)(beta)](0 < beta < 1), which is usually observed in many disorder materials. Through the studies of the PPC effect under various conditions, such as different temperature, different photon energy of photoexcitation, and different Ge content, we identify that the alloy potential fluctuations induced by compositional disorder are the origin of the PPC effect in Si1-xGex/Si quantum wells. (C) 1998 American Institute of Physics. [S0021-8979(98)00914-1].