A betavoltaic battery is a nuclear battery that converts energy from beta particles released by a beta emitting radioactive source, such as tritium, into electrical power. The application of tritiated amorphous silicon as an intrinsic energy conversion semiconductor for betavoltaic devices is presented. Thin-film contact potential tritiated amorphous silicon cells have been built. These cells, called tritium batteries, have a specific power of 24 watts per kilogram, a full load operating life of 10 years, and an overall efficiency on the order of 25%. Cheap, long-life, high energy density, low power batteries.
The entrapment of tritium is particularly apt in this application as it is readily substituted for the hydrogen present in hydrogenated amorphous semiconductors with good intrinsic electronic properties. Radioisotopes other than tritium, may also be used as a source of energetic electrons as well as other forms of energetic nuclear radiation such as krypton-85 for example.
Tritiated amorphous films are mechanically stable, free of flaking or blistering, with good adherence to the substrate and may be simultaneously deposited onto both conducting and insulating substrates using a discharge in tritium plasma. The silicon layer sputtered in a tritium/argon ambient at temperatures below 300oC results in a tritiated amorphous silicon firlm with the tritium concentration being variable from 5 to 30% depending upon deposition conditions.