抄録
The quantum efficiency and the thermal activation energy of photogeneration of charge carriers in α-sulfur have been investigated in the energy range from 3.6 to 6.2 eV. Quantum efficiency (η) was (1.7±0.3)×10−2 both for electrons and holes in the energy range from 5.1 to 6.2 eV. Below 5.1 eV, η decreases with decreasing the photon energy. The thermal activation energy (ε) for electrons and holes is constant, (0.02±0.005) eV in the energy range from 4.0 to 6.2 eV, Below 4.0 eV, ε increases with decreasing the photon energy (hν) and fits a linear relation ε=4-hν. The absorption band of single crystal of α-sulfur is similar to the band of a sulfur molecule in cyclohexane. It may be concluded that the mechanism of the intrinsic photogeneration, though it is a single quantum process, is not a direct band-to-band transition, but it is an autoionization process, in which electrons are excited to molecular states and then are autoionized to the continum states.
