Enhanced Betavoltaic Signals in Asymmetric Metal–Semiconductor–Metal SiC Schottky Devices: An Experimental and Simulation Investigation with ⁶³ Ni, ⁹⁰ Sr/ ⁹⁰ Y, and ¹⁷⁷ Lu β Exposure

Betavoltaic devices, which convert the kinetic energy of β particles into direct electrical power, are a promising technology for energy generation. In particular, betavoltaic devices based on 4H n-type SiC Schottky diodes are becoming one of the preferred options due to their high available quality and maturity of fabrication. This study compares a traditional Schottky diode, which consists of a Ni Schottky contact and a multilayered, heat-treated Ti/Ni/Ag ohmic contact (annealed at >700 °C), to a simplified Schottky diode based on the asymmetric metal–semiconductor–metal (AMSM) concept. In the latter, the conventional ohmic contact is replaced with a low work function metal, Hf. Electron beam induced current (EBIC) measurements and exposure to 63Ni, 90Sr/90Y, and 177Lu demonstrate that the betavoltaic performance is preserved while significantly simplifying the fabrication process. Additionally, Geant4 simulation is used to compare the energy deposition dose of the different radioactive sources to experimental device performance in relation to the depletion region width. The simulation results are in good agreement with the experimental data, in which 177Lu exposure, with the largest deposition dose overlapping the depletion region, yields the highest power density of 624 nW/cm2.