Novel High Speed Devices and Heterostructures Prepared by Molecular Beam Epitaxy
Abstract
Study of the small-bandgap III-V compounds InAs(1-x)Sb(x) and GaAs (1-x)Sb(x) has continued towards the goal of eventual application to long wavelength infrared sources and detectors. Optical characterization of these small bandgap compounds was performed, resulting in the best reported low- temperature photoluminescence linewidth of 7.6 meV for a GaAs(0.46)Sb(0.54) sample. The first experimental data on the band alignment of the GaSb/GaAs system was reported from the results of photoreflectance measurements. A heavy- hole band offset of approx. 1.7 for GaAs(0.9)Sb(0.1), establishing a type-II structure with electrons in the GaAs layers and holes in the GaAs(1-x)Sb(x) layers. Electrical characterization of these materials was also studied by variable temperature Hall measurements. For the GaAs(1-x)Sb(x) material grown on InP, a two-acceptor model was forwarded to describe the Hall coefficient temperature behavior. The growth of InAs(1-x)Sb(x) on GaAs, is studied using the effects of graded layers, strained-layer superlattices, and titled substrates to reduce or constrain the misfit dislocations induced by the large lattice mismatch (7.2 - 14.6% for 0 < or = x < or = 1). Transmission electron microscopy on the microstructure and interfacial structure of the InSb layers on (100) GaAs has revealed the accommodation of the misfit strain by square arrays of a/2 01(1) edge-type dislocations. From Hall measurements, room temperature electron mobilities as high as 57000 sqcm/Vs were reported in a 4.6 micro thick unintentionally-doped InSb layer on GaAs.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 13, 1989
- Accession Number
- ADA205002
Entities
People
- Hadis Morkoç
Organizations
- University of Illinois Urbana–Champaign