ELECTROTHERMAL INVESTIGATION OF THE SWITCHING EFFECT IN P-TYPE TLINSE2, TLINTE2, AND TLGATE2, CHAIN CHALCOGENIDE SEMICONDUCTORS

Large p-type TlInSe2, TlInTe2, and TlGaTe2 single crystals have been g rown by the Bridgman-Stockbarger method, starting from stoichiometric melts. The first observations of the switching process in p-type TlGaT e2 single crystal are reported. Current-voltage (I-V) characteristics of symmetrical In/p-TlInSe2/In, In/p-TlInTe2/In, and In/p-TlGaTe2/In s tructures exhibit two distinct regions: an ohmic region at low current densities and nonlinear regions (S-shape) having negative differentia l resistance (NDR) at moderate and higher current densities. An electr othermal model was used to explain the nonlinear behavior. The nonline ar behavior of the I-V curves was studied at different ambient tempera tures in the 100-340K region; 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. The electrothermal model is a satisfactory explanation.