Modeling and simulation of a high power InGaP/GaAs heterojunction alphavoltaic battery irradiated by americium-241

The design of semiconductor-based heterojunction structures can be turned useful to raise the efficiency of nuclear micro-batteries. In this study, we have investigated a micro-power alphavoltaic battery by using a lab-made software. The nuclear battery consists of an In0.49Ga0.51P/GaAs heterostructure irradiated by americium-241 (Am241) alpha particles with an average kinetic energy of 5.485 MeV. The alphavoltaic battery exhibits an overall active area of 1 cm2. Based on a comprehensive analytical model, the device current density-voltage J(V) and output electric power P(V) characteristics are simulated extracting the energy conversion efficiency. The model takes into account the reflection of the incident alpha particles, the ohmic losses, the effect of the boundary between the two layers, and the depletion region borders. Different values of the radioisotope apparent activity density, the emitter and base dopant concentrations, and the surface recombination velocities in both the front and back layers are considered during the simulations to optimize the battery performance. The present study reports that by irradiating by a 2.4 mCi/cm2 Am241 source, the obtained energy conversion efficiency of the battery can reach 10.31% with a maximum output power density of 16.07 µW/cm2. Therefore, In0.49Ga0.51P/GaAs heterostructure coupled with Am241 seems a promising design for long-term energy supply in harsh environments.