4H-SiC p-n junction betavoltaic micro-nuclear batteries based on 14C source with enhanced performance

The long half-life and the high decay energy of beta sources play a critical role in improving the performance of betavoltaic micro-nuclear batteries. In this study, the pure beta source C-14 in the form of powder, which can be transformed into an ultra-thin film by using ((C6H5NH)-C-14)(2)CO, was selected to design planar 4H-SiC p-n junction betavoltaic batteries. A comprehensive model was developed utilizing the Monte Carlo code and the COMSOL Multiphysics code to predict the output performance. As a result, based on a 100 mu m-thick ((C6H5NH)-C-14)(2)CO source with a maximum power density of 1.86 mu W/cm(2) and the current fabrication technology of 4H-SiC p-n junction, we optimized the thicknesses of the p(-)-type region (4.2 mu m) with a doping concentration of N-a = 3 x 10(16) cm(-3) and the n(-)-type region (5.8 mu m) with a doping concentration of N-d = 2 x 10(14) cm(-3). The corresponding predicted performance values included the short-circuit current density of 0.1 mu A/cm(2), the open-circuit voltage of 2.15 V, and the maximum power density of 0.2 mu W/cm(2). Moreover, the energy conversion efficiency of the semiconductor converter can reach 10.6%, while the overall battery efficiency was determined to be 2.9%. Therefore, this research provides a feasible structure for a planar 4H-SiC p-n junction energy converter utilizing the ((C6H5NH)-C-14)(2)CO source and presents a powerful model for predicting the performance of planar betavoltaic batteries.