Nanopower betavoltaic microbatteries

This paper presents theoretical and experimental studies on betavoltaic microbatteries using low-level radiation from 1/spl sim/100 milliCurie /sup 63/Ni thin films. The model indicates that powers of hundred nanowatts are possible with 50-100 milliCurie radioisotope sources. Two types of betavoltaic microbatteries are developed and tested. One is the planar silicon pn-diode with electroplating of /sup 63/Ni thin film, and the other is the bulk micromachined pn-junction structure with the inverted pyramid array. The obtained power is on the scale of one-nanowatt with an open circuit voltage of 128 millivolts, and a short circuit current of 2.86 nA. The output power can be increased using greater activity and efficient collector designs.