EFFECT OF HEAT-TREATMENT ON SOME OF THE ELECTRICAL-PROPERTIES OF SB2TE3 SINGLE-CRYSTALS GROWN BY THE BRIDGMAN METHOD

In this paper Sb2Te3 single crystals are prepared by the Bridgman technique and annealed in different atmospheres (N2 and H-2). Thermoelectric power and electrical properties of these annealed and unannealed samples are determined as a function of temperature. X-ray diffraction, energy dispersive X-ray spectroscopy (EDX), and Hall effect are used to determine and characterize the structures, the chemical compositions, and the electrical properties of the samples. It is found that the electrical properties of Sb2Te3 change remarkably with heat treatment and exhibit a semiconducting behaviour at low temperature. The evolution of the electrical resistivity leads us to confirm the presence of impurity levels, their activation energies are computed from the slope of the dark resistivity versus temperature curves and compared with available data from literature. After annealing, the resistivity, the mobility, and the activation energies are improved and this is due to passivation of the impurities and to their removal from the dislocations.