Variable Band Gap Materials for Thermophotovoltaic Generators

摘要

The objective of this research program was to design and develop direct band gap solar cells which would have high below band gap energy (infra-red (IR)) reflectivity for use in high efficiency thermophotovoltaic (TPV) energy conversion systems. Two types of customized GaAs cells were grown on intrinsic or semi-insulating GaAs substrates with either p-type GaAs or Al(.9) Ga (.1) As stop-etch layers. Holes were drilled through the substrate using a laser photochemical etch technique. Cells with high IR reflectivity and low series resistance were fabricated by drilling a hole which stopped at the contact layer of the cell with the Al(.9) Ga(.1) As stop-etch layer and then depositing gold in the hole and on the back surface. Measurements of these customized cells indicate that IR reflectivities in excess of 90%, corresponding to TPV efficiencies in excess of 35%, are feasible. Keywords include: Thermophotovoltaic energy conversion; GaAs solar cells; Photochemical etching; GaAs; Free carrier absorption; and Infra-red reflectivity.