Simulation of Radiation-Induced Structural and Optical Modifications in ZnO:S/SI Thin Film Structures

The research studied ZnO thin films containing 3 at.% sulphur (S) on silicon (1 μm) through Geant4 simulations for radiation analysis. Analysis of ZnO thin films (400 nm) doped with 3 at.% sulphur (S) on a 1 μm thick silicon substrate through Monte Carlo simulation platform Geant4 considered energy absorption together with particle penetration depth and ionization and secondary electron generation and optical property changes as the study examined different electron radiation energies from 3 keV to 10 keV. The ZnO:S layer absorbed most of the incoming electron energy in the 3-5 keV range which produced increases in defects near the surface while ionization occurred. When electrons used 9-10 keV energies they penetrated the full substrate layer which caused silicon to receive most of the energy absorption. The highest change in parameters occurred at the film-substrate junction when the energy reached 7 keV. All modeling findings demonstrated that the total absorbed energy together with secondary electron production and defect density reaching up to 10⁷ increased rapidly with electron energy acceleration. The decrease in optical properties occurs because defects exist at different depths while energy absorption takes place. Electrical and optical characteristics of ZnO:S/Si can be regulated through electron irradiation procedures according to this research. Results from this study will function as fundamentals for creating sensors and optoelectronic devices and protective coatings which operate effectively under high radiation conditions.