Low-temperature electrical resistivity of cupric telluride (CuTe) thin films

Abstract

Thin films of cupric telluride (CuTe) of thickness from 50 to 200 nm have been prepared using a thermal evaporation technique onto well-cleaned glass substrates kept at 300 K under a vacuum better than 2 × 10-5 mbar. After annealing the deposited films at 375 K for an hour, the resistivity of these films and that of bulk CuTe were measured using the four-probe technique as a function of temperature from 80 to 310 K. It is found that the bulk sample of CuTe exhibits metallic behaviour and the thin films show semiconducting behaviour. Activation energies of the films have been evaluated and are in the range 0.05 and 0.15 eV. The metallic behaviour of bulk CuTe down to 4 K indicates that the variable range hopping mechanism is absent in CuTe at least down to liquid helium temperature. X-ray diffraction analysis confirmed the composition and polycrystalline nature of the CuTe films. The grain size of CuTe thin films, estimated from atomic force microscopy measurements, is around 40 nm. © 2008 WILEY-VCH Verlag GmbH & Co. KGaA.