Function Of InAs Research Articles

Effects of growth rate variations on carrier lifetime and interface structure in InAs/GaSb superlattices

InAs/GaSb superlattice samples have been grown with variations in interface design and growth rates of InAs and GaSb. Time resolved photoluminescence measurements show no decrease in Shockley–Read–Hall carrier lifetime for samples with rougher interfaces and a rise and then decrease in lifetimes with increasing growth rate. Interface growth sequences that tend to increase the effective growth rate of the superlattice result in longer lifetimes. The peak lifetime of 82ns occurs at a growth rate of 0.5ml/s for both InAs and GaSb. Growth rates from 0.2 to 0.8ml/s show similar lifetimes, while those at faster growth rates show reduced lifetimes. Transmission electron microscopy and high resolution x-ray diffraction measurements show no variation in superlattice structural quality as a function of InAs and GaSb growth rates. Comparison of photoluminescence results with GaInAsSb quaternary structures suggests that changes in lifetime are not due to changes in superlattice structure, but result from point defects in the layers.

Temperature dependence of the dielectric function and critical-point energies of InAs

We report the complex dielectric function of InAs for energies from 0.74 to 6.54 eV and temperatures from 22 to 675 K. The complex dielectric function was determined by using spectroscopic ellipsometry. The critical-point (CP) structures at low temperatures are blue-shifted and are sharpened significantly relative to those observed at high temperatures, which can be explained by using the reduction of the electron-phonon interaction and the thermal expansion. The CP energies are determined by using lineshape fittings to numerically calculated second energy derivatives of the dielectric function. The obtained CP energies are fit to a phenomenological expression that contains the Bose-Einstein statistical factor and to a linear equation.

Above GaSb barrier in type II quantum well structures for mid-infrared emission detected by Fourier-transformed modulated reflectivity

AbstractModulation spectroscopy in its Fourier-transformed mode has been employed to investigate the optical properties of broken gap ‘W’-shaped GaSb/AlSb/InAs/InGaSb/InAs/AlSb/GaSb quantum well structures designed to emit in the mid infrared range of 3–4 μm for applications in laser-based gas sensing. Besides the optical transitions originating from the confined states in the type II quantum wells, a number of spectral features at the energy above the GaSb band gap have been detected. They have been analyzed in a function of InAs and GaSb layer widths and ultimately connected with resonant states in the range of AlSb tunneling barriers.

Transport properties of InSb and InAs 0.1Sb 0.9 thin films sandwiched between Al 0.1In 0.9Sb layers grown by molecular beam epitaxy

InAs 0.1Sb 0.9 active layers sandwiched between Al 0.1In 0.9Sb insulating layers were grown on GaAs(1 0 0) substrates by molecular beam epitaxy (MBE) where the InAs 0.1Sb 0.9 active layers had no lattice mismatch with the Al 0.1In 0.9Sb layers. Basic transport properties and electronic properties of the InAs 0.1Sb 0.9 were studied as functions of InAs 0.1Sb 0.9 thickness. Very large electron mobility of InAs 0.1Sb 0.9 active layers and very small thickness dependence at <500 nm were observed. The large lattice mismatch effect observed for InSb active layers grown directly on GaAs substrates and for an InSb active layer sandwiched between Al 0.1In 0.9Sb was almost completely eliminated.

Proposal of interband tunneling structures with strained layers

A type of interband tunneling structure with strained layers is proposed. InxGa1−xSb/ InxAl1−xSb/InAs/InxAl1−xSb/InxGa1−xSb strained resonant interband tunneling structures are theoretically studied by calculating current-voltage characteristics using realistic band structure and making comparisons to analogous unstrained structures. The results show that the interband tunneling windows of strained structures can be expanded by the introduction of strain in the InAs quantum-well layer. With a wider interband tunneling window, the peak current density is enhanced due to the broader tunneling transmission spectrum and higher bias required for resonant interband tunneling. The peak current density is also examined as a function of InAs well width for different InAlSb barrier widths.

Electronic Structure of Type-II InAs/GaSb Misaligned Superlattice

The Energy band edges of type-II InAs/GaSb (001) misaligned superlattices as functions of InAs and GaSb layer thicknesses are calculated by a pseudopotential method with quick convergency. The results show the trend of deep-shallow transitions of impurities in the superlattices. The regime in which the superlattice changes from semiconductor to semimetal is also showed.