Optical Properties of Indium-Doped Tin Dioxide Thin Films Irradiated by Alpha Particles

Abstract

This study investigates the effect of α-particle irradiation (5.48 MeV) on the optical properties of pure and indium-doped (1.5 and 3 at.%) SnO₂ thin films prepared by the spin-coating technique. Results of the UV–visible spectroscopy in the range 300–1100 nm show that increasing the indium content reduces the optical transmittance and narrows the direct band gap. The initial band gaps were 3.84 eV (pure), 3.80 eV (1.5% In), and 3.74 eV (3% In). After irradiation, the band gaps decreased slightly to 3.82 eV, 3.78 eV, and 3.73 eV, respectively. This reduction is attributed to radiation-induced defects that introduce localized states near the band edges.