Simulation and Optimization Design of SiC-Based PN Betavoltaic Microbattery Using Tritium Source

Abstract

In this paper, the Monte Carlo method and numerical model are used to build the electrical model of a SiC-based betavoltaic microbattery using a 3H source, and the influences of structural parameters and the surface recombination effect on the output characteristics of the SiC PN battery are simulated. According to Monte Carlo calculations based on the energy spectrum of the 3H source, the ionization energy deposition approaches the exponential distribution along the depth direction, and most of the 22rs are concentrated near the material surface. The ionization energy deposition data is converted into non-equilibrium carrier information for the numerical simulation of the battery’s output characteristics. The simulation results show that the conversion efficiency of the battery rises first, and then decreases with the increase of the doping concentration of the N region. This is because the N region-doping affects the depletion region width and the built-in electrical potential at the same time. After considering the surface recombination effect, the conversion efficiency decreased significantly. Thinning the thickness of or moderately reducing the doping concentration of the P region will weaken the surface recombination effect.

Limit Efficiency of a Silicon Betavoltaic Battery with Tritium Source

“…This formula suggests that one should use broad-bandgap materials for best efficiency value. For this reason, recent studies have been focused on such materials as diamond [11,12], silicon carbide [13][14][15][16][17], gallium arsenide [18], zinc oxide [19], and gallium nitrate [20]. If one adopts Klein's parameters [9], one obtains the ultimate efficiency of a beta-battery based on a broad-bandgap semiconductor 1/A = 36%; using the parameters from [10], one obtains an even more optimistic estimate of 65%, which, admittedly, is too good to be true.…”