Three-Dimensionally Structured Betavoltaics

Abstract

In this work we demonstrate three-dimensionally structured silicon diodes for use as a betavoltaic power source in conjunction with147Pm. The concept of using a three-dimensionally structured semiconductor to increase the power density and efficiency of a betavoltaic device has existed for some time, even specifically for the combination of Si and Pm [1], [2], however this work is the first demonstration of infiltration of the radioisotope into the structured semiconductor; the previous works utilized either an e-beam gun or a sealed source to demonstrate power generation. MCNP simulations were carried out to determine the optimal feature sizes for maximizing power density and efficiency. We have fabricated three devices, which were filled with approximately 3, 7, and 28 mCi of PmCl3 respectively. These devices produced an output current greater than what could be achieved in a coplanar device, demonstrating successful infiltration of the radioisotope.