Mitigation of Surface Oxidation in Sb2Se3 Thin Films Via Te Doping: An Effective Strategy Towards Realization of Efficient Electronic Devices

Abstract

Sb2Se3 and Te-doped Sb2Se3 films of ∼250 nm film thickness were deposited using a facile thermal evaporation technique from the bulk powder synthesized via the melt quenching technique. Thermogravimetric analysis of pure and Te-doped Sb2Se3 alloys in bulk form indicates decomposition of the alloys in the 303–673 K temperature range. The X-ray diffraction pattern revealed single-crystalline orthorhombic phase stabilization of as-prepared alloys in bulk as well as in the annealed thin films. Phase formation is also evident in the recorded Raman spectra from the appearance of two peaks at ∼189 and 210 cm–1, which are ascribed to the Sb2Se3 Ag mode. The absorbance spectra of as-annealed pure Sb2Se3 and Te-incorporated Sb2Se3 films exhibit significant reduction with Te doping due to an increase in the optical band gap. The conductivity in as-annealed Sb2Se3 and (0.08%)Te-doped Sb2Se3 films recorded from 308 K (room temperature) to 392 K show a decrease in DC conductivity and activation energy with the insertion of Te in the Sb2Se3 system. Such a trend in conductivity and activation energy is attributed to arise as a result of structural changes as well as defect passivation enabled by Te insertion in the alloy. Interestingly, the DC conductivity is in the range of ∼10–7 Ω–1 cm–1 at 308.5 K, which is 10 times higher than that of the previously reported conductivity of Sb2Se3 films. Presently, the nonpreferential grain growth, undesirable deep-level defects, and surface oxidation in Sb2Se3 thin films are pressing issues that render them unsuitable for practical application in devices. Herein, this study brings to the fore a strategy to overcome these issues by doping Te in Sb2Se3 thin films, and hence it is a step forward towards the replacement of environmentally toxic CdTe-based devices.