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

Studies on the materials development of Ga1 - xInxAsySb1 - y alloys for the rmophotovoltaic (TPV) devices are reported. Ga1 - xInxAsySb1 - y epilayers were grown lattice-matched to GaSb substrates by organometallic vapor-phase epitaxy (OMVPE) using all organometallic precursors including triethylgall ium, trimethylindium, tertiarybutylarsine, and trimethylantimony with dieth yltellurium and dimethylzinc as the n- and p-type dopants, respectively. Th e epilayer characteristics of these alloys depend on growth temperature, In and As content, V/III ratio, and substrate misorientation. A mirror-like s urface morphology and room-temperature photoluminescence (PL) are obtained for GaInAsSb layers with peak emission in the wavelength range between 2 an d 2.5 mu m. The material properties of the metastable alloys improve for gr owth temperature decreasing from 575 degrees C to 525 degrees C and with de creasing In and As content, as based on epilayer surface morphology, X-ray diffraction, and low-temperature PL spectra. In general, GaInAsSb layers gr own on (1 0 0)GaSb substrates with a 6 degrees toward (1 1 1)B misorientati on exhibit overall better material quality than layers grown on the more st andard substrate (1 0 0) 2 degrees toward (1 1 0). Consistent growth of hig h-performance lattice-matched GaInAsSb TPV devices is also demonstrated. (C ) 1998 Published by Elsevier Science B.V, All rights reserved.