Modelling and performance analysis of a GaN-based n/p junction betavoltaic cell

In this work, we optimized the performance of a gallium nitride (GaN)-based n/p junction betavoltaic cell irradiated by the radioisotope nickel-63 (Ni63). In particular, we developed a lab-made software starting from an analytical model that takes into account a set of fundamental physical parameters for the cell structure. The simulations reveal that, by using a Ni63 radioisotope source with a 25 mCi/cm2 activity density emitting a flux of beta-particles with an average energy of 17.1 KeV, the cell performs a conversion efficiency (η) in excess of 26%, thus approaching the theoretical limit for a GaN-based device. The other electrical parameters of the cell, namely the short-circuit current density (Jsc), open-circuit voltage (Voc), and maximum electrical power density (Pmax) are 240nA∕cm2, 2.87 V, and 660nW∕cm2, respectively. The presented analysis can turn useful for understanding the theoretical background needed to better face GaN-based betavoltaic cell design problems.