Demonstration of a Three-Dimensionally Structured Betavoltaic

In this work, we present a demonstration of a high-aspect ratio, three-dimensionally structured betavoltaic device. High-aspect ratio silicon PIN diodes were used as the semiconductor absorber and 147PmCl3 was used as the beta emitter. Three devices were fabricated with 147Pm activities of 2.4 mCi, 7.4 mCi, and 29.5 mCi. The device with the highest activity produced an initial power output of 200 nW and was monitored over a period of 8 months to observe the current–voltage behavior over time, during which time the output current decreased in accordance with the radioactive half-life of 147Pm. Small deviations in the output current of a few percent during the long-term measurement were found to be attributable to the humidity in the room where the experiment was done. The output current generated from the devices was 68–77% of the theoretical maximum, indicating significant infiltration of the radioisotope into the ridged structures.