Raman Scattering Study of Lattice Vibrations in the Type-II Superlattice InAs/InAs1−xSbx

Abstract

InAs/InAs1-xSbx superlattice system differ distinctly from two well-studied superlattice systems GaAs/AlAs and InAs/GaSb, in terms of electronic band alignment, common-element at the interface, and phonon spectrum overlapping of the constituents. This fact leads to unique electronic and vibrational properties of the InAs/InAs1-xSbx system when compared to the other two systems. In this work, we report a polarized Raman study on the vibrational properties of the InAs/InAs1-xSbx SLs as well as selected InAs1-xSbx alloys, all grown on GaSb substrates by either MBE or MOCVD, from both growth surface and cleaved edge. In the SL, from the (001) backscattering geometry, an InAs-like LO mode is observed as the primary feature and its intensity is found to increase with increasing Sb composition; from the (110) cleaved edge backscattering geometry, an InAs-like TO mode is observed as the main feature in two crosspolarization configurations, but an additional InAs-like "forbidden" LO mode was observed in two parallel-polarization configurations. InAs1-xSbx alloys lattice-matched to the substrate (xSb ~ 0.09) grown by MBE were also found to exhibit the "forbidden" LO mode, implying the existence of some unexpected [001] modulation, but the strained xSb ~ 0.35 samples grown by MOCVD were found to behavior like a disordered alloy. The primary conclusions are (1) the InAs-like LO or TO mode could be either a confined or quasi-confined mode in the InAs layers of the SL or extended mode of the whole structure, depending on the Sb composition; (2)InAs/InAsSb and InAs/GaSb SLs exhibit significantly different behaviors in the cleaved edge geometry, but qualitatively similar in the (001) geometry; and (3) the appearance of the "forbidden" LO-like mode is a universal signature for SLs and bulk systems resulting from mixing of phonon modes due to structural modulation or symmetry reduction.3

Monolithic Growth of Patternable III–V on LiNbO3

“…The Raman spectrum of LT-TLP-grown InP and InAs presented in Figure c identifies discernible transverse (TO) and longitudinal (LO) mode peaks. For InAs, these peaks are observed at 218 cm –1 (TO) and 239 cm –1 (LO), while for InP, peaks are noted at 300 cm –1 (TO) and 348 cm –1 (LO). , Additionally, the Raman spectrum exhibits peaks corresponding to LiNbO 3 , aligning with findings from prior studies on LiNbO 3 . Alongside the crystalline validation, the electron mobility of the III and V templated films is determined through Hall effect measurements.…”

Phonon Analysis of 2D Organic‐Halide Perovskites in the Low‐ and Mid‐IR Region

“…[10] These modes have long been experimentally observed and confirmed in semiconducting superlattices grown by molecularbeam epitaxy. [11][12][13][14][15][16] Recently, Dahod et al [17] have proposed using the Rytov model, first used in seismic tomography and then expanded to describe the vibrations in layered materials, [18,19] to account for the low-frequency (<30 cm −1 ) Raman features of layered hybrid perovskite materials. However, due to the difficulty in obtaining the precise material parameters, the assignment cannot be considered definite.…”