Optical band gap of Sn_(0.2)Bi_(1.8)Te_3 thin films

摘要

Sn_(0.2)Bi_(1.8)Te_3 thin films were grown using the thermal evaporation technique on a (001) face of NaCl crystal as a substrate at room temperature. The optical absorption was measured in the wave number range 500-4000 cm~(-1). From the optical absorption data the band gap was evaluated and studied as a function of film thickness and deposition temperature. The data indicate absorption through direct interband transition with a band gap of around 0.216 eV. The detailed results are reported here.