Bandgap-Tailored Thermophotovoltaic Devices for Narrow-Band Radioisotope Power Sources

Radioisotopes have been used as a source of energy for space applications where there is insufficient solar energy to use standard photovoltaic arrays. Thermophotovoltaic devices (TPV) provide a means of converting the radioisotope thermal energy efficiently into electricity. We propose to fabricate TPV devices from Gallium Indium Antimonide (GaInSb) with a bandgap tailored to a radioisotope source with a selective oxide emitter. Our models show that the use of GaInSb alloys instead of Gallium Antimonide will significantly increase the system efficiency. The project objective is to demonstrate GaInSb TPV devices by using a process similar to the existing process for GaSb cells, and developing the individual steps such as diffusion, metalization and photolithography. The project will result in GaInSb sample devices that will demonstrate the required wavelength sensitivity. The improved system efficiency will result in a lower spacecraft power system weight for a specific power.