Effect of Ge and Pb Impurities on the Optical Properties of Amorphous (Sb2Se3)90Sn10 Thin Films

Abstract

The as prepared samples of [(Sb₂Se₃)₉₀Sn₁₀]₉₅ M₅ [M = Ge, Pb] chalcogenide system were amorphous as evidenced by X-ray diffraction studies. The optical band gap has been estimated with the help of Taucs relation for the as-deposited [(Sb₂Se₃)₉₀Sn₁₀]₉₅M₅ thin films. It is observed that the optical band gap increase with increase in the Ge and Pb content, which may be due to decrease in the density of defect states. This  can  be also explained based on Urbach energy, which is a disorder parameter, and its value decrease with increase in impurity content, which also favors the previous result obtained. The value of tailing parameter (known as the structural disorder parameter) decrease with increase in impurity content, which again shows the change in structure of the system with impurity.

 Keyword: XRD(X-ray Diffraction); EDX(Energy Dispersive X-ray); SEM(Scanning Electron Microscopy)