Design of high-efficiency Ga₂O₃-based betavoltaic battery utilizing the MG-HJ-PND structure

Attributed to the wide bandgap property of gallium oxide (Ga₂O₃), Ga₂O₃-based betavoltaic batteries offer advantages such as small volume, strong radiation resistance, high-temperature stability, and chemical stability, demonstrating great potential for micro-medical devices, aerospace systems, and military equipment. Typically, betavoltaic batteries are based on a diode structure. However, the high carrier concentration in Ga₂O₃ material results in an excessively thin depletion region at zero bias. This limitation reduces the efficiency of collecting radiation-generated electron–hole pairs (RG-EHPs) in Ga₂O₃-based betavoltaic batteries, resulting in a low energy conversion efficiency (η_c), a crucial indicator for evaluating the performance of betavoltaic batteries. In this study, Ga₂O₃-based betavoltaic batteries utilizing diode structures were investigated using Monte Carlo FLUKA particle transport software and Sentaurus TCAD semiconductor device simulation software. A Ga₂O₃-based betavoltaic battery featuring a multi-groove heterojunction PN diode structure (MG-HJ-PND) was designed, with the radioactive source positioned within the grooves and p-nickel oxide (p-NiO) injected along the groove edges, which not only enhanced RG-EHP generation but also extended the depletion region, ultimately achieving a high η_c of 10.38% in the Ga₂O₃-based betavoltaic battery. Moreover, the performance of the Schottky barrier diode and heterojunction PN diode (HJ-PND) structures based on Ga₂O₃, silicon, and silicon carbide material was compared. The high-efficiency Ga₂O₃-based betavoltaic battery, based on the MG-HJ-PND structure, was shown to be a promising candidate for permanent micro-energy sources.