Integrated amorphous silicon designs for high-efficiency betavoltaic batteries

The self-absorption effect of the radioactive source is one of the factors that affect the output performance of betavoltaic batteries. This paper proposes a betavoltaic battery using amorphous silicon (a-Si:T) as the transducer material, which effectively overcomes the limitations of self-absorption on efficiency and power output. To clearly demonstrate the mitigation of the self-absorption effect, the structure of the conventional device was optimized using Monte Carlo simulations and Silvaco TCAD software. The proposed device’s performance was compared to the conventional one under identical structural parameters. At a-Si:T thickness of 1.6 μm, the conventional device had a maximum output power density of 3.66 nW/cm2 and an overall efficiency of 0.07%, while the proposed device achieved 30.23 nW/cm2 and 0.61%, respectively. The study also evaluated a-Si:T thicknesses from 0.2 to 1.6 μm, finding the proposed device consistently outperformed the conventional one, with the performance gap widening from 2.2 times at 0.2 μm to 8.3 times at 1.6 μm. The study confirmed that a-Si:T material can effectively overcome the energy loss caused by the self-absorption effect. It also demonstrated that materials that can serve both as a radioactive source and as a transducer have great potential in enhancing the performance of betavoltaic batteries.