The proposed innovation will dramatically improve the performance of tritium-powered betavoltaic batteries through the development of a high-aspect ratio, expanded surface area p/n junction composed of indium gallium phosphide. The enhanced surface area features will be built using reactive ion etch (RIE) modified germanium substrates via metalorganic chemical vapor deposition (MOCVD). The proposed 3-dimensional betavoltaic p/n junction will provide a cost saving of up to 90%, while increasing energy density to up to ten times that of lithium batteries. Such an advanced semiconductor device will produce much higher power outputs than are possible with existing state-of-the-art devices. It will provide the battery a life span in excess of 20 years with the broad-range temperature-insensitivity benefits normally associated with betavoltaics. This increased power/energy density for tritium betavoltaics will open up pathways for significant advances in power solutions for diminutive sized, low-power microelectronic devices that may be used in Cubesat and in-space power systems. Example applications include microwatt-to-milliwatt autonomous 20+ year sensors/microelectronics for use in structural monitoring, mesh networks, tagging and tracking wireless sensors, medical device implants, and deep space power where solar is not easily available. Tritium betavoltaics are capable of addressing this power niche for devices requiring reliable, uninterrupted power through extremes of temperature, longevity and diminutive form factors where traditional batteries cannot operate.