Preferential grain growth, tunable bandgap and topological insulating to bulk state modification induced via Ag ion irradiation in antimony telluride nanostructured thin film

Abstract

Ion irradiation has been an important technique to alter the physical properties of materials for desired applications. Sb2Te3 thin films deposited via vacuum thermal evaporation procedure are Ag ion irradiated at various fluences. Preferential grain growth along the [104] direction and reduction in optical bandgap from 1.37 eV for unirradiated thin films to 1.14 eV for irradiated thin films is noticed. The value of the Seebeck coefficient decreases with ion fluences 1 × 1010 and 1 × 1012 ions/cm2 owing to the variation in carrier concentration as evident from the Hall measurements. Interestingly, the value of the Seebeck coefficient of the pristine film (457 μV/K at 313 K) is higher than previously reported value in these materials. The study might be catchy to tailor the physical properties of alloys for thermophotovoltaic applications.