High-open-circuit voltage diamond alpha-voltaic battery with interface reconstructed by amorphous gallium oxide

Alpha-voltaic batteries have significant prospects in deep space and sea, polar deserts, and biomedicine because of their micro-volume, radiation resistance, long lifetime, and environmental adaptability. Diamond is an ideal material for alpha-voltaic batteries with high open-circuit voltage and radiation stability, owing to its wide bandgap and high displacement energy. However, solving the problems of interface leakage and low open-circuit voltage caused by Shockley-Read-Hall (SRH) recombination at the oxygen-terminated diamond Schottky junction and Fermi-level pinning continues to pose a significant challenge. In this study, we fabricated a diamond alpha-voltaic battery with an amorphous gallium oxide dielectric layer that modulates the diamond/gold Schottky interface. Using ²⁴¹Am with an activity of 8.85 μCi/cm², an open-circuit voltage of 2.41 V was achieved, which is the highest reported in the literature. In addition, a short-circuit current density of 6.6 nA/cm² and a maximum output power of 9.72 nW/cm² were obtained. The total conversion efficiency of the alpha-voltaic battery was calculated to be 3.7 %. Then we verified the repeatability and temperature-variable stability of diamond nuclear batteries with amorphous gallium oxide-modulated interfaces. Analysis of the band arrangement of diamond and amorphous gallium oxide revealed the extraction–passivation relationship of interface carriers. Based on analysis of the chemical bond states at the interface, we proposed a new mechanism for the reconstruction of the oxygen-terminated diamond interface induced by amorphous gallium oxide. These results provide a new idea for increasing the open-circuit voltage of nuclear batteries.