Lattice-matched epitaxial GaInAsSb/GaSb thermophotovoltaic devices

The materials development of ${\mathrm{Ga}}_{\text{1−x}}{\mathrm{In}}_x{\mathrm{As}}_y{\mathrm{Sb}}_{\text{1−y}}$ alloys for lattice-matched thermophotovoltaic (TPV) devices is reported. Epilayers with cutoff wavelength 2–2.4 μm at room temperature and lattice-matched to GaSb substrates were grown by both low-pressure organometallic vapor phase epitaxy and molecular beam epitaxy. These layers exhibit high optical and structural quality. For demonstrating lattice-matched TPV devices, $p$ - and $n$ -type doping studies were performed. Several TPV device structures were investigated, with variations in the base/emitter thicknesses, and some with the incorporation of a high-bandgap GaSb or AlGaAsSb window layer. Significant improvement in the external quantum efficiency and open circuit voltage is observed for devices with an AlGaAsSb window layer compared to those without one.