In this work, a nuclear battery with a 14C source was developed to improve the electrical properties of betavoltaic batteries. The betavoltaic battery energy converters containing different semiconductors, such as Ga2O3, GaAs, GaN, GaP, Si, and SiC, were evaluated to convert the 14C radioisotope source energy into electrical energy. The electrical output properties of the betavoltaic battery were established through numerical calculation for two structures of the p-n junction and Schottky barrier (with Ag, Al, Au, Mo, Ni, Pd, and Pt as Schottky metals). The optimum thickness of the 14C radioisotope and its energy deposition distribution within the semiconductors were determined using the Monte Carlo method.

In the betavoltaic battery with the p-n junction configuration, the optimized doping concentration yielded a maximum output power density and energy conversion efficiency of 20.97 μW·cm−2 and 7.20%, respectively, for the Ga2O3 semiconductor. In contrast, these parameters for the Pt-Si Schottky barrier betavoltaic were obtained at 1.34 μW·cm−2 and 0.46%, respectively, with the 20-nm thickness of the Pt Schottky metal layer and a doping concentration of 1015 cm−3. These findings are valuable and helpful for assembling reasonable betavoltaic batteries.