Authors:D. Meier, A. Garnov, J. Robertson, J. Kwon, and T. Wacharasindhu
The specific energy density from radioactive decay is five to six orders of magnitude greater than the specific energy density
in conventional chemical battery and fuel cell technologies. We are currently investigating the use of liquid semiconductor
based betavoltaics as a way to directly convert the energy of radioactive decay into electrical power and potentially avoid
the radiation damage that occurs in solid state semiconductor devices due to non-ionizing energy loss. Sulfur-35 was selected
as the isotope for the liquid semiconductor demonstrations because it can be produced in high specific activity and is chemically
compatible with known liquid semiconductor media.
The design, fabrication, and testing of a 4H-SiC Schottky betavoltaic nuclear battery based on MEMS fabrication technology
are presented in this paper. It uses a Schottky diode with an active area of 3.14 mm2 to collect the charge from a 4 mCi/cm263Ni source. Some of the critical steps in process integration for fabricating silicon carbide-based Schottky diode were addressed.
A prototype of this battery was fabricated and tested under the illumination of the 63Ni source with an activity of 0.12 mCi. An open circuit voltage (VOC) of 0.27 V and a short circuit current density (JSC) of 25.57 nA/cm2 are measured. The maximum output power density (Pmax) of 4.08 nW/cm2 and power conversion efficiency (η) of 1.01% is obtained. The performance of this battery is expected to be significantly
improved by using larger activity and optimizing the design and processing technology of the battery. By achieving comparable
performance with previously constructed p–n or p–i–n junction energy conversion structures, the Schottky barrier diode proves
to be a feasible approach to achieve practical betavoltaics.