Study of interfaces in GaInSb/InAs quantum wells by high-resolution X-ray diffraction and reciprocal space mapping

Abstract

The electrical and optical properties of advanced epitaxial structures, such as quantum wells and superlattices are strongly influenced by the quality of their interfaces. The GaInSb/InAs system is particularly important because of its promise for use in infrared detection in the 8–14 μm ranges. In this material system the two compounds do not share a common anion, and different bond types exist at the interface depending upon the growth parameters. We have looked at single quantum-well structures grown with solid source molecular beam epitaxy such that a distinct interface type would be found in each sample. X-ray rocking curves and full dynamical simulations were performed for each quantum well structure. Quantum wells with three types of interfaces were grown and analyzed; random interfaces, Sb-like interfaces, and As-like interfaces formed with a one monolayer group III deposition followed by a five second group V soak. With the exception of the interfaces, all three SQWs have nominally the same structure; 5000 Å of GaSb buffer layer grown upon a GaSb substrate, a 150 Å quantum well with 35 Å Ga 0.75In 0.25Sb barriers and a final GaSb cap layer of 50 Å thickness. Well-resolved Pendellösung fringes were found in all samples indicating high quality in the epitaxial layers and interfaces. The SQW with the As-like interfaces had the highest degree of quality as evidenced by persistence of the fringes.