Molecular beam epitaxy of strained-layer InAs/GaInSb superlattices for long-wavelength photodetectors

We report on the growth and characterization of strained-layer InAs/Ga1−xInxSb superlattices for long-wavelength photodetectors. The thickness and alloy composition x < 0.4 of the layers were designed to produce narrow superlattice energy gaps of <50 meV for optical absorption in the terahertz spectral range. The structures were grown on GaSb (1 0 0) substrates by solid-source molecular beam epitaxy. The structure and surface quality were analyzed by using X-ray diffraction, scanning transmission electron microscopy, energy-dispersive spectroscopy, and Rutherford backscattering spectroscopy. Transmittance and reflectance spectra were measured to evaluate the optical properties. The characterization results demonstrated the feasibility of the pseudomorphic growth of strained InAs/GaInSb superlattices and their promising optical properties for long-wavelength photodetectors.