Investigation of a temperature tolerant InGaP (GaInP) converter layer for a Ni-63 betavoltaic cell

A prototype InGaP p+–i–n+ mesa photodiode was studied for its potential as the energy conversion device in a 63Ni betavoltaic cell; its electrical performance was analysed across the temperature range −20 °C to 100 °C. The results show that the InGaP detector when illuminated with a laboratory 63Ni radioisotope beta particle source had a maximum output power of 0.92 pW at −20 °C, this value decreased at higher temperatures. A decrease in the open circuit voltage and in the cell internal conversion efficiency were also observed when the temperature was increased: at −20 °C, the open circuit voltage and the cell internal conversion efficiency had values of 0.69 V and 4%, respectively. A short circuit current of 4.5 pA was measured at −20 °C.