I-U dependence of TlInX2 (X=Se,Te) single crystals: The Ohmic and S-type regions

Abstract

Electrical conductivity measurements were performed on TlInSe2 and TlInTe2 single crystals. The corresponding current-voltage (I-U) characteristics consist of two parts: An Ohmic part, at low current densities, and a nonlinear one of the S type, at moderate and higher current densities. In the latter part a well-formed negative-differential-resistance (NDR) region appears. Acceptor levels and their concentrations were determined from lnp versus 103/T curves measured in the Ohmic region of the corresponding I-U curves. The nonlinear behavior of the I-U curves was studied at different ambient temperatures; the sample temperature and the threshold voltage of the NDR region were examined as a function of the current density and the ambient temperature, respectively. © 1991 The American Physical Society.