Growth and characterization of InAsSb/GaInAsAb/AlGaAsAb/GaSb heterostructures for wafer-bonded thermophotovoltaic devices

InAsSb/GaInAsSb/AlGaAsSb/GaSb heterostructures were grown by organometallic vapor phase epitaxy for wafer bonding and epitaxial transfer. The InAsSb epilayer, which is used as an etch-stop layer, is the template for subsequent growth of GaInAsSb/AlGaAsSb/GaSb thermophotovoltaic device structures. Atomic force microscopy images of as-grown InAsSb epilayers exhibit extreme roughness with features that are aligned with the substrate miscut orientation. Interior InAsSb surfaces, which were prepared by selectively etching the cap layers, are atomically smooth. Thus, the InAsSb surface undergoes extensive roughening during cool down. X-ray characterization of InAsSb/GaSb/GaInAsSb heterostructures that were grown without interruption between successive layers shows that GaInAsSb material quality is maintained. GaInAsSb/AlGaAsSb heterostructures wafer-bonded to GaAs substrates with an internal reflector have enhanced optical quality compared to unbonded heterostructures.