Temperature Anomalies of Transport Properties in SnTe Epitaxial Thin Films

Abstract

The temperature dependences of electrical conductivity σ, Hall coefficient R H and charge carrier mobility μ H in the temperature range of 77 to 300 K were obtained for SnTe epitaxial thin films of different thicknesses (0.2 to 0.6 μm) and with charge carrier concentration of pH77= 3.5 x 10 20 cm -3 . In the vicinity of 200 K anomalies of R H and μ H , were detected most pronounced for the sample with h =0.6 μm bearing evidence of qualitative changes in the electron and lattice subsystems of the crystal. The observed anomalies are attributed to the phase transition consisting of a redistribution of nonstoichiometric defects (cation vacancies) over the crystal lattice. It is suggested that in contrast to bulk crystals, in thin films more favorable conditions for a restruction of the defect subsystem are established which lead to configurational changes which reduce the total energy of the crystal. These processes are controlled to a great extent by kinetic factors.