Monte Carlo analysis of ionizing radiation effects in ZnS:Ag and GaN:Al layers of alphavoltaic cells

Abstract

This study employs Monte Carlo simulations using SRIM/TRIM software to assess depth-dependent radiation damage in alphavoltaic ZnS:Ag/GaN:Al bilayers. The structure, consisting of a 20 μm ZnS:Ag scintillator and a 2 μm GaN:Al semiconductor, was modeled under perpendicular irradiation by a 5.485 MeV alpha particle beam from an Am-241 source. The simulations reveal an alpha particle range of 20.56 μm with 0.58 μm straggling, showing significant damage extending into the GaN:Al layer. This is concerning for alphavoltaic efficiency, as GaN:Al is more susceptible to displacement damage than ZnS:Ag. Ionization profiles indicate that energy deposition primarily occurs in ZnS:Ag, with the Bragg peak slightly extending into GaN:Al. To mitigate damage in GaN:Al and enhance energy conversion in ZnS:Ag, it is recommended to increase ZnS:Ag thickness to at least 22.5 μm. These findings highlight the importance of SRIM/TRIM simulations in optimizing multilayer designs for alphavoltaic applications prior to experimental validation.