Graphene/porous GaN Schottky Betacell

Abstract

Betavoltaic batteries have advantages over other batteries due to their high energy density, long life, insensitivity to the environment, and small size. This study aims to design a new structure for betavoltaic batteries using porous GaN with a wide energy bandgap. Many nanowires, coated with graphene, are formed on the surface of GaN. Graphene makes a Schottky junction with GaN and creates an internal electric field to separate electron-hole pairs in the depletion region. In our simulation, Ni63 with an activity of 1 mCi, radiant energy of 17 keV, and radiant flux of 6 Pa is used for beta radiation. The structure is simulated in a TCAD 3D simulator, and an auxiliary function written in C++ is employed to simulate the beta beam. This function provides the spatial distribution of the generated electron-hole pairs in GaN as the input data to our simulator to calculate the battery characteristics. The simulation results indicated that the open-circuit voltage, short-circuit current, fill factor (FF), output power, and efficiency were obtained as 1.22 V, 61.5 nA, 37%, 28.4 nW, and 28.4%, respectively. The effect of changes in the radioisotope source activity and temperature on the betavoltaic battery performance is also investigated. The use of porous GaN, along with the graphene as the semi-metal in Schottky junctions with GaN, has caused a good increase in the performance of our proposed betavoltaic cell in comparison with previously published works.