Electrical properties of Se1−xTex crystals

Single crystals of Se_1?xTe_x (with x varying from 0.1 to 0.9) were successfully grown by the Bridgman method. D.C. Hall effect and temperature dependence of π of these crystals were measured. π at 300°K is found to decrease and the carrier concentration to increase approximately exponentially with x. The temperature dependence of π shows that the conduction is thermally activated. At low temperature (< 300 °K) extrinsic conduction is dominant with the value of the activation energy decreasing from 0.065 to 0.006 eV as x increases from 0.1 to 0.9. At higher temperature, intrinsic conduction is observed for alloys with x = 0.4, 0.5, 0.6 and 0.8 yielding the values of intrinsic band gaps (E_g). The values of E_g are found to decrease with x.