Optimization design of GaAs-based betavoltaic batteries with p-n junction and Schottky barrier structures

This paper presents the calculation model and the optimization design of the GaAs-based betavoltaic batteries with p-n junction and Schottky barrier structures. First of all, by using the Monte Carlo code, the transport process and energy deposition distribution of the Ni-63 source beta particles in the GaAs material are simulated. The relationships between the output parameters of batteries and the physical parameters of energy converter such as p-n junction depth, Schottky metal thickness, depletion region width and doping concentrations are discussed through the numerical calculation. For the GaAs p-n junction battery, the maximum output power density of 0.135 mu Wcm(-2) can be achieved when the junction depth is x(j) = 0.05 mu m, the doping concentrations are N-a = 10(18)cm(-3) and N-d = 2x10(15)cm(-3). Meanwhile, the short-circuit current density, open-circuit voltage, filling factor and energy conversion efficiency are 0.254 mu Acm(-2), 0.638 V, 83.3% and 2.63%, respectively. Among the selected metals of Au, Pd, Ni and Pt for the GaAs Schottky barrier diodes, the Pt-GaAs battery has the best output performance due to its large work function. The maximum output power density of 0.169 mu Wcm(-2) can be achieved when a 20 nm thick Schottky metal Pt is selected and the doping concentration is N-d=10(15c)m(-3) mu Acm(-2), 0.835 V, 86.5% and 3.29%, respectively.