May 17, 2005
New Silicon, Nuclear Battery Technology Promises Longer Life
Researchers at the University of Rochester have found a way to fabricate nuclear batteries that are already ten times more efficient than current nuclear batteries and have the potential to be 160 times as efficient. The nuclear batteries would last for at least ten years without recharge or replacement, making them ideal for implanted medical devices, deep-space probes or deep-sea sensors.
"Our society is placing ever-higher demands for power from all kinds of devices. For 50 years, people have been investigating converting simple nuclear decay into usable energy, but the yields were always too low. We've found a way to make the interaction much more efficient, and we hope these findings will lead to a new kind of battery that can pump out energy for years," said Phillippe Fauchet, professor of electrical and computer engineering at the University of Rochester and co-author of the research.
The battery technology based on current generated when radioactive beta particles hit a semiconductor PN junction is called betavoltaics. However, unlike photovoltaics, which generate current in a PN junction exposed to photons, the amount power produced by betavoltaics has been too limited to be practical. One of the reasons is that as particles in the tritium gas, the source of beta particles used in the betavoltaics, decay, half of them shoot off in a direction that misses the silicon. To solve this problem the University of Rochester researchers use standard semiconductor industry fabrication techniques to etch a layer of silicon with pits about a micron wide and over 40 microns deep. The pits are then coated with a material a tenth of a micron thick to form a PN junction. The pits are filled with tritium gas and only particles that are fired straight up can escape the pit. The rest hit the PN junction and generate electricity.
BetaBatt was formed to capitalize on the technology and recently received a technology commercialization grant from the National Science Foundation, which funded the initial research.
More information, links and pictures are available in the University of Rochester news release New 'Nuclear Battery' Runs 10 Years, 10 Times More Powerful and the National Science Foundation Press Release Silicon Solution Could Lead to a Truly Long-Life Battery - New devices may provide power for decades.