Abstract
The effect of thickness and heat treatment on the structural and optical properties of Sb2Te3 thin films fabricated by using flash evaporation technique were investigated. The as-deposited films were found to be stoichiometric. For the as-deposited and annealed samples of thickness in the range of 20.7–120.5 nm, large variations in transmittance and reflectance were observed for wavelength below 2000 nm due to strong absorption, while slight variations were observed above 2000 nm. The optical constants, n and k, measured in the range of 500–4000 nm, increased slightly by annealing the samples at 573 K for 2 h in air and a red shift was observed. Allowed indirect transitions were observed for the as-deposited and the annealed samples. The results showed two energy gaps for these transitions varied from 0.28 to 0.31 eV for the as-deposited samples and from 0.56 to 0.54 eV for the annealed films. The spectral distribution of the real part of the dielectric constant ε′ showed a maximum at 0.73 eV for the as-deposited films decreased to 0.65 eV by annealing.