Betavoltaic device

A betavoltaic device (betavoltaic cell or betavoltaic battery) is a type of nuclear battery which generates electric current from beta particles (electrons) emitted from a radioactive source, using semiconductor junctions. A common source used is the hydrogen isotope tritium. Unlike most nuclear power sources which use nuclear radiation to generate heat which then is used to generate electricity, betavoltaic devices use a non-thermal conversion process, converting the electron-hole pairs produced by the ionization trail of beta particles traversing a semiconductor. Betavoltaic power sources (and the related technology of alphavoltaic power sources) are particularly well-suited to low-power electrical applications where long life of the energy source is needed, such as implantable medical devices or military and space applications. Betavoltaics were invented in the 1970s. Some pacemakers in the 1970s used betavoltaics based on promethium, but were phased out as cheaper lithium batteries were developed. Early semiconducting materials weren't efficient at converting electrons from beta decay into usable current, so higher energy, more expensive—and potentially hazardous—isotopes were used. The more efficient semiconducting materials used today can be paired with relatively benign isotopes such as tritium, which produce less radiation. The Betacel was considered the first successfully commercialized betavoltaic battery. The primary use for betavoltaics is for remote and long-term use, such as spacecraft requiring electrical power for a decade or two. Recent progress has prompted some to suggest using betavoltaics to trickle-charge conventional batteries in consumer devices, such as cell phones and laptop computers. As early as 1973, betavoltaics were suggested for use in long-term medical devices such as pacemakers. In 2018 a Russian design based on 2-micron thick nickel-63 slabs sandwiched between 10 micron diamond layers was introduced. It produced a power output of about 1 μW at a power density of 10 μW/cm3.