Theoretical prediction of time-related performance of GaN-based p–n junction betavoltaic battery

Betavoltaic batteries can meet long-term energy supply needs. However, due to the decay of the radioactive source, the output performance of battery will change over time, and the laws of this change require elucidation to aid the battery engineer. In this study, the influences of time on the apparent power density and β-energy spectrum of the 63 Ni source were clarified. Moreover, the structural parameters, including the p-region, n-region doping concentrations, and junction depth of GaN-based (hexagonal) p–n junction, were optimized, which are 2 × 1017 cm–3, 1014 cm–3, and 0.1 μm, respectively. In particular, the time-related performance trends were analyzed, and a formula for the maximum output power density deterioration was obtained, which can be used to evaluate the performance of 63 Ni GaN-based p–n junction betavoltaic battery within 200 years. The simulation results showed that the maximum output power density of battery after 50 years is 0.243 μW cm−2, which is only 60% of the initial value. In addition, the other output performances, namely, the short-circuit current density, open-circuit voltage, fill factor, and conversion efficiency are 0.096 μA cm−2, 2.67 V, 94.3%, and 20.5%, respectively.