One example is a betavoltaic cell that has been fabricated using a semiconductor that includes, but is not limited to, Silicon Carbide (SiC), Silicon (Si), Gallium Arsenide (GaAs), Indium Gallium Arsenide (InGaAs), Gallium Nitide (GaN), Gallium Phosphide (GaP), or Diamond, and uses through wafer via holes or other fabrication techniques to form both positive (+ve) and negative (−ve) contacts on the front and back sides of the cell. In another example, several of these cells with +ve and −ve contacts on the front and back sides of the cell are arranged vertically and/or horizontally to form customized parallel and/or series combinations that produce a close packed, energy dense betavoltaic composite unit, with increased power outputs relative to a single cell. In another example, tritium or a metal tritide is used as the radioisotope source for the cells.
