Optical phonons as a probe to determine both composition and strain in In _x Al _(1−x) As quantum dots embedded in an AlAs matrix

Abstract

InxAl (1−x) As quantum dots (QDs) embedded in an AlAs matrix were studied using Raman scattering and photoluminescence spectroscopy techniques. The longitudinal optical (LO) and transverse optical (TO) In-As bond vibrations frequencies are found to depend on both composition and strain. Using different scattering geometries (allowed for LO or for TO modes) we were able to obtain the experimental values of these frequencies. By comparing these values with the calculated frequencies, one can determine both the mean composition (stoichiometry parameter x) and the biaxial strain in InxAl (1−x) As QDs embedded in an AlAs matrix. Our approach is simple, non-destructive and fast.

Localized Strain Measurement in Molecular Beam Epitaxially Grown Chalcogenide Thin Films by Micro-Raman Spectroscopy

“…Micro-Raman spectroscopy has been used as a noninvasive and versatile tool to map the mechanical strain/stress in large domain single crystalline materials on arbitrary substrates, such as MBE III–V materials, graphene, − multilayered semiconductors, metal oxides and 2D layered chalcogenides . As Raman peaks can be influenced by temperature, charge density, polarization, , and defects, it is critical to choose the phonon modes that are most sensitive to strain/stress. On the same sample, both the phonon frequency shift and the full width at half maximum (FWHM) vary less than 0.1 cm –1 .…”

Optical properties of tensile-strained and relaxed Ge films grown on InGaAs buffer

“…It is known that the band gap (in meV) for solid alloy In x Al 1Àx As depends on the stoichiometric parameter x as E g ¼ 3020-3390xþ740x 2 (Refs. [30][31][32] and with the required parameter (x ¼ 0.37) is 1870 meV. This is almost two times more than that of In 0.37 Ga 0.63 As and it gives us hope that in such a heterostructure one can achieve a high probability of optical transitions from Ge films in IR range.…”

Interaction of optical and interface phonons and their anisotropy in GaAs/AlAs superlattices: Experiment and calculations

“…Because of this, experimental stud ies of the angular anisotropy of phonons are scarce, although this problem remains urgent in the physics of phonons in solid nanostructures [20]. The develop ment of experimental equipment and the advent of micro Raman spectrometers for studying Raman scattering from microobjects has made it possible to use the scattering geometry, in which the wave vector of light is not only perpendicular to superlattice layers, but can also lie in its plane when the light is incident on the face of the superlattice [20][21][22][23][24]. We used this method in this paper.…”