Recent progress in GaInAsSb thermophotovoltaics grown by organometallic vapor-phase epitaxy

Abstract

Studies on the materials development of Ga 1− x In x As y Sb 1− y alloys for thermophotovoltaic (TPV) devices are reported. Ga 1− x In x As y Sb 1− y epilayers were grown lattice-matched to GaSb substrates by organometallic vapor-phase epitaxy (OMVPE) using all organometallic precursors including triethylgallium, trimethylindium, tertiarybutylarsine, and trimethylantimony with diethyltellurium and dimethylzinc as the n- and p-type dopants, respectively. The epilayer characteristics of these alloys depend on growth temperature, In and As content, V/III ratio, and substrate misorientation. A mirror-like surface morphology and room-temperature photoluminescence (PL) are obtained for GaInAsSb layers with peak emission in the wavelength range between 2 and 2.5 μm. The material properties of the metastable alloys improve for growth temperature decreasing from 575°C to 525°C and with decreasing In and As content, as based on epilayer surface morphology, X-ray diffraction, and low-temperature PL spectra. In general, GaInAsSb layers grown on (1 0 0)GaSb substrates with a 6° toward (1 1 1)B misorientation exhibit overall better material quality than layers grown on the more standard substrate (1 0 0) 2° toward (1 1 0). Consistent growth of high-performance lattice-matched GaInAsSb TPV devices is also demonstrated.