Photogeneration of Charge Carriers in α-Sulfur below 3.6 eV

Abstract

The light intensity and temperature dependence of photogeneration of charge carriers in α-sulfur was investigated in the energy range from 2.2 to 3.6 eV. It was confirmed that, in this energy range, free carriers are generated through two processes, that is, (1) an extrinsic single quantum process which depends strongly on surface conditions and (2) an intrinsic double quantum process which is independent of the surface states. In the extrinsic single quantum process, the thermal activation energies both for electrons and holes are 0.03 eV and its value is almost the same as that of the generation above 4 eV.