Photoconductivity in Single-Crystal Tellurium

Abstract

Measurements of the steady-state and transient photoconductive behavior in the extrinsic range are presented and interpreted in terms of a simple trapping model. The change of electrical conductivity due to steady irradiation by light of 3.5-μ wavelength is proportional to the first power of the intensity of the light for low excitation, becoming proportional to the square root at higher excitation. The small signal responsive time constant is 350 μsec for T<77°K in the dark and decreases with either thermal or optical excitation. A model composed of 0.5×1013 traps/cm3 of energy level 0.072 eV above the top of the valence band and an unspecified recombination mechanism account quantitatively for the observed effects. Details of the sample preparation process are given.