POINT-DEFECTS IN M(2-X)IN(X)TE(3) (M=SB OR BI) CRYSTALS

Spectral dependences of the reflectance R in the plasma-resonance frequency range have been measured on (0001) cleavage faces of Sb2-xInxTe3 (x = 0.0-0.41) single-crystal samples grown from elements of 99.999% purity by means of a modified Bridgman technique. The plasma-resonance frequency (and hence the concentration P of holes) has been determined from the interpretation of the experiment R = f(v) curves. The dependence on P on the content of In atoms shows a monotonic decrease from a value of 6.4 x 10(25) m(-3) for x = 0 to 1 X 10(25) m(-3) for x = 0.41. The account for the decrease in the concentration of holes, we propose a model based on the assumption that the introduction of In atoms into the crystals results in a decrease in the concentration of antisite defects and, at the same time, in a change in the concentration of vacancies in the Te sublattice of Sb2Te3 crystals. The P = f(x) dependence for Sb2-xInxTe3 crystals is compared with the variation in the concentration of free charge carriers with In content in Bi2-xInxTe3 crystals.