Structural and dynamical properties of Bridgman-grown CdSe[subscript x]Te[subscript 1−x] (0<x≤0.35) ternary alloys
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Talwar-2013-Structural and dynamical properties.pdf
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Author(s)
Talwar, Devki N.
Feng, Zhe Chuan
Lee, Jyh-Fu
Becla, Piotr
Date Issued
April 2013
Journal
Physical Review B
Publisher
American Physical Society
Citation
Talwar, Devki N., Zhe Chuan Feng, Jyh-Fu Lee, and P. Becla. “Structural and Dynamical Properties of Bridgman-Grown CdSe[subscript x]Te[subscript 1−x] (0
Version
Final published version
Abstract
Measurements of the Raman scattering and extended x-ray-absorption fine-structure (EXAFS) spectroscopy are reported on a series of Bridgman-grown zinc-blende CdTe[subscript 1−x]Se[subscript x] (0.35 ≥ x > 0.05) ternary alloys to empathize their lattice dynamical and structural properties. Low-temperature Raman spectra have revealed the classic CdTe-like (TO[subscript 1], LO[subscript 1]) and CdSe-like (TO[subscript 2], LO[subscript 2]) pairs of optical phonons. The composition-dependent peak positions of the LO[subscript 2] modes exhibited shifts towards the higher-energy side, while those of the LO[subscript 1] phonon frequencies have unveiled the slight redshifts. Detailed analyses of EXAFS data by using the first-principles bond orbital model have enabled us to estimate both the lattice relaxations and nearest-neighbor radial force constants around the Se/Te atoms in the CdTe/CdSe matrix. These results are methodically integrated in the “average t-matrix” formalism within the Green's-function theory for defining the impurity perturbations to comprehend the composition-dependent optical phonons in CdTe[subscript 1−x]Se[subscript x] alloys. Based on our comprehensive calculations of impurity modes in the low-composition regime x → 0, we have assigned the weak phonon feature observed near ∼175 cm[superscript −1] in the low-temperature infrared reflectivity spectroscopy study to a Se[subscript Te] localized vibrational mode.
MIT Department
MIT Materials Research Laboratory
Massachusetts Institute of Technology. Department of Materials Science and Engineering
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DOI of Published Version
https://doi.org/10.1103/PhysRevB.87.165208
