OPTICAL-ABSORPTION BEHAVIOR OF AGSBTE2 THIN-FILMS

Bulk AgSbTe2 possesses a cubic structure of NaCl type with a = 3.038 A . AgSbTe2 thin films were prepared by thermal evaporation under vacuum (10-(6)torr). The room temperature deposited films were polycrystalli ne in nature and consisted of two-phases (AgSbTe2 + Ag Te-2) with AgSb Te2 as a major phase. The optical absorption behaviour of AgSbTe2 thin films was studied. The energy gap (E(g)), the refractive index (n), r elative permittivity epsilon' and the dielectric loss epsilon '' were estimated for AgSbTe2 thin films as well as the effect of heat treatme nt, in the wavelength range 400-2500 nm. Analysis of the absorption co efficient data revealed the existence of the indirect and allowed dire ct transitions with optical energy gaps E(g)(i) = 0.71 eV and E(g)(d) = 1.65 eV at 300 K. These values were found to increase with increasin g annealing temperature.