Effect of interfacial bonding on the structural and vibrational properties of InAs/GaSb superlattices

Abstract

We have studied InAs/GaSb superlattices (SLs) grown with either InSb-like or GaAs-like interfaces (IFs) on top of a GaSb buffer layer on (100) GaAs substrates. The InAs layer thickness was varied from 4 to 14 monolayers (ML) while the GaSb layer thickness was kept fixed at 10 ML. The type of IF bonds realized was verified by Raman scattering from mechanical IF modes. High-resolution X-ray diffraction using one- and two-dimensional mapping of symmetric and asymmetric reflections allowed us to determine independently the lattice parameters parallel and perpendicular to the growth direction. The GaSb buffer layer was found to be fully relaxed whereas the SLs with InSb-like IFs were coherently strained to the in-plane lattice parameter of the GaSb buffer for InAs layer thicknesses exceeding 6 ML. The strain distribution within the SLs with GaAs-like IFs was obtained from simulations of the X-ray reflection profiles. The SLs were found to be coherently strained close to the GaSb buffer and showed increasing strain relaxation with increasing distance from the buffer layer. In addition, these simulations provide an accurate determination of the SL periods. Well-resolved Raman spectra of backfolded longitudinal acoustic (LA) phonons were observed showing for SLs with ZnSb-like IFs folded LA phonon lines up to the seventh order. The spectrum of quasiconfined optical SL phonons was examined by Raman spectroscopy and by IR reflection. A detailed analysis of the IR reflection spectra allowed an independent determination of the individual layer widths within the SL stack, including the spatial extent of the GaAs-like IF mode

Lattice vibration modes in type-II superlattice InAs/GaSb with no-common-atom interface and overlapping vibration spectra

“…[17][18][19][20][21][22][23][24] Most of them were performed in the (001) back-scattering geometry, with only one major Raman peak observed at around 236 238cm -1 assigned generally as a SL-LO mode. It was believed that the overlapping of the bulk phonon modes would make it difficult to resolve the confined and extended modes.…”

Overview of antimonide based III-V semiconductor epitaxial layers and their applications at the center for quantum devices

“…Based on the theoretical modeling and simulation we chose the optimum structure for a room temperature detector at λ = 11 µm. The structure consisted of a 2 µm superlattice with 48Å InAs, 30Å GaSb, and one monolayer of InSb at the interfaces as it is shown to improve the optical and electrical quality of the superlattice [68]. Finally, the superlattice was capped with a thin 200Å GaSb layer.…”

Quantitative evaluation of microtwins and antiphase defects in GaP/Si nanolayers for a III–V photonics platform on silicon using a laboratory X-ray diffraction setup

“…A more precise evaluation has been carried out based on the Williamson-Hall evaluation method (Williamson & Hall, 1953;Herres et al, 1996;Kirste et al, 2005), as described by Durand et al (2011b). Herres and co-workers attributed the line profile broadening to three mechanisms: the tilt, the average crystallite size and the inhomogeneous strain.…”