A diamond p-n junction is used to convert the decay energy of 63 Ni source into electrical energy. The selfabsorption effect of the 63 Ni source, the backscatter process and the transport process of beta particles in diamond materials are studied. Then the theoretical maximum of electrical properties and the energy conversion efficiencies of diamond-63 Ni p-n junction batteries are achieved. Finally, a feasible design of 𝑝 + 𝑝 − 𝑛 + junction battery, which has the maximum output power density of 0.42 𝜇W/cm 2 and the optimal device conversion efficiency of 26.8%, is proposed.

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For the 63NiO-Si heterojunction betavoltaic nuclear battery, the energy deposition of the energy conversion material itself was simulated by Monte Carlo simulation, and the structure of the 63NiO-Si heterojunction was optimized based on the theoretical calculation results. When the thickness of 63NiO is 4 μm and the doping concentration of Si is 1 × 1015 cm−3, the short-circuit current density, open-circuit voltage, fill factor, and maximum output power density of the nuclear battery are 1.22 μA · cm−2, 3.17 V, 0.95, 3.67 μW · cm−2. In addition, the output performance of 63Ni/NiO-Si heterojunction betavoltaic nuclear cell was calculated in this study. Under the condition that the activity of the radioactive source and the thickness of NiO(63NiO) are the same in the two structures, the proposed structure (63NiO-Si) has greatly improved the output performance of the nuclear battery by reducing the energy lost from radioactive source self-absorption.

This paper presents a simulation model to predict the performance of GaAs-based betavoltaic batteries with a p–n junction structure, in which the carrier transport and collection characteristics were studied. First, the electron–hole pair generation rate in the GaAs material under the irradiation of a 63Ni source was calculated using the Monte Carlo codes. Furthermore, by simulating the energy band structure, electric field distribution, and current density distribution in batteries with the finite element analysis software COMSOL Multiphysics, we analyzed the effects of structure parameters on the output performance. Our simulation results showed that the short-circuit current density (Jsc), open-circuit voltage (Voc), maximum output power density (Pm), and energy conversion efficiency (η) of the batteries are significantly affected by the thicknesses and doping concentrations of the p-region and n-region (Hp-GaAs, Hn-GaAs, Na, and Nd). The optimized GaAs-based battery with an Hp-GaAs value of 0.1 μm, an Hn-GaAs value of 9.9 μm, an Na value of 3.98 × 1016 cm−3, and an Nd value of 1 × 1015 cm−3 can achieve a Pm value of 0.080 μW/cm2. The related Jsc, Voc, and η values are 0.234 μA/cm2, 0.49 V, and 1.55%, respectively. When the top and bottom heavily doped layers are introduced, the Pm value of the battery is enhanced by 7.5% compared to that of the battery without heavily doped layers due to the formed drift fields.

This paper describes the theoretical calculation and optimization design of the PN junction betavoltaic batteries with 4H–SiC-based energy converter and titanium tritide source. The self-absorption of radioactive isotope sources and the energy deposition distribution in the semiconductor converter are simulated using the Monte Carlo method. The relationship between doping concentrations and basic factors such as minority carrier diffusion lengths and the width of the depletion region are analyzed via the calculation formulas. Then the maximum output power density and energy conversion efficiency are calculated. The optimal thickness of the titanium tritide film is about 0.7 μm, the doping concentrations are 2.5 × 1016 cm−3, and the junction depth of PN junction is 0.1 μm. The surface recombination velocities of electron and hole are 1 × 106 cm/s, respectively. The maximum output power density and energy conversion efficiency are 0.22 μW/cm2 and 2.37%, respectively.