Model for Long ‐ Wavelength Optical‐Phonon Modes of Mixed Crystals

Genzel, L.; Martin, T. P.; Perry, C. H.

doi:10.1002/pssb.2220620108

Cited by 216 publications

(110 citation statements)

References 16 publications

Supporting

Mentioning

101

Contrasting

Unclassified

Order By: Relevance

“…In ZnTeSe it is commonly admitted that the impurity modes are screened by the disorder-induced phonon density of states, and thereby do not give rise to any observable feature in the Raman/IR spectra. 10 Note that in the MREI-VCA schemes related to InGaP and ZnTeSe, the basic TO branches, as obtained simply by joining the corresponding parent and impurity modes, cross each other (not shown), which contradicts the expected trend of quasi-parallel TO branches.…”

Section: Introductionmentioning

confidence: 89%

Unification of the phonon mode behavior in semiconductor alloys: Theory andab initiocalculations

Pagès¹,

Postnikov²,

Kassem³

et al. 2008

Phys. Rev. B

View full text Add to dashboard Cite

We demonstrate how to overcome serious problems in understanding and classification of vibration spectra in semiconductor alloys, following from traditional use of the virtual crystal approximation (VCA). We show that such different systems as InGaAs (1-bond→1-mode behavior), InGaP (modified 2-mode) and ZnTeSe (2-bond→1-mode) obey in fact the same phonon mode behavior -hence probably a universal one -of a percolation-type (1-bond→2-mode). The change of paradigm from the 'VCA insight' (an averaged microscopic one) to the 'percolation insight' (a mesoscopic one) offers a promising link towards the understanding of alloy disorder. The discussion is supported by ab initio simulation of the phonon density of states at the zone-center of representative supercells at intermediary composition (ZnTeSe) and at the impurity-dilute limits (all systems). In particular, we propose a simple ab initio 'protocol' to estimate the basic input parameters of our semi-empirical 'percolation' model for the calculation of the 1-bond→2-mode vibration spectra of zincblende alloys. With this, the model turns self-sufficient.

show abstract

Section: Introductionmentioning

confidence: 89%

Unification of the phonon mode behavior in semiconductor alloys: Theory andab initiocalculations

Pagès¹,

Postnikov²,

Kassem³

et al. 2008

Phys. Rev. B

View full text Add to dashboard Cite

show abstract

“…I n a recent model calculation [2] this question is answered in the second way. Following this theory, additional modes should appear in any mixed system.…”

Section: Introductionmentioning

confidence: 99%

Raman Scattering Studies on (NH₄)Cl_1−xBr_x Mixed Crystals in the Tetragonal Phase

Bauhofer¹,

Genzel²,

Perry³

et al. 1974

Physica Status Solidi (b)

Self Cite

View full text Add to dashboard Cite

Raman measurements have been performed on the mixed system (NH,)C11 -.Br, in the tetragonal phase. For intermediate x-values, new peaks are found in the acoustical frequency region of the spectra, whose mode strengths are proportional to x and (1 -x ) , respectively. Adopting the assumption that the concept of a Brillouin zone is still useful in a mixed crystal, the Raman active modes of the tetragonal phase of the mixed crystals are identified with the M-point modes of the cubic p-phase. The experimental data are compared with a simple calculation based on the REI-model. Am Mischsystem (NH,)Cl1 -.Brz in der tetragonalen Phase wurden Ramanmessungen durchgefiihrt. Im akustischen Frequenzbereich der Spektren werden fur mittlere z-Werte neue Moden gefunden, deren Intensitaten proportional zu x beziehungsweise (1 -x ) sind.Unter der Annabme, daB das Konzept der Brillouin-Zone auch fur einen Mischkristall anwendbar ist, konnen die ramanaktiven Moden der tetragonalen Phase der Mischkristalle mit den M-Punkt-Moden der kubischen p-Phase identifiziert werden. Die experimentellen Ergebnisse werden mit einer einfachen, auf dem REI-Model1 basierenden Rechnung verglichen.

show abstract

“…This mixed-crystal system exhibits a 'two-mode' behaviour, 53 i.e. it exhibits both GaAs-like and AlAs-like modes.…”

Section: Single-and Multi-layers and Superlatticesmentioning

confidence: 99%

Raman spectroscopy of optical phonon confinement in nanostructured materials

Arora

Rajalakshmi

Ravindran

et al. 2007

J Raman Spectroscopy

359

294

View full text Add to dashboard Cite

If the medium surrounding a nano-grain does not support the vibrational wavenumbers of a material, the optical and acoustic phonons get confined within the grain of the nanostructured material. This leads to interesting changes in the vibrational spectrum of the nanostructured material as compared to that of the bulk. Absence of periodicity beyond the particle dimension relaxes the zone-centre optical phonon selection rule, causing the Raman spectrum to have contributions also from phonons away from the Brillouin-zone centre. Theoretical models and calculations suggest that the confinement results in asymmetric broadening and shift of the optical phonon Raman line, the magnitude of which depends on the widths of the corresponding phonon dispersion curves. This has been confirmed for zinc oxide nanoparticles. Microscopic lattice dynamical calculations of the phonon amplitude and Raman spectra using the bond-polarizability model suggest a power-law dependence of the peak-shift on the particle size. This article reviews recent results on the Raman spectroscopic investigations of optical phonon confinement in several nanocrystalline semiconductor and ceramic/dielectric materials, including those in selenium, cadmium sulphide, zinc oxide, thorium oxide, and nano-diamond. Resonance Raman scattering from confined optical phonons is also discussed.

show abstract

Model for Long ‐ Wavelength Optical‐Phonon Modes of Mixed Crystals

Cited by 216 publications

References 16 publications

Unification of the phonon mode behavior in semiconductor alloys: Theory andab initiocalculations

Unification of the phonon mode behavior in semiconductor alloys: Theory andab initiocalculations

Raman Scattering Studies on (NH₄)Cl_1−xBr_x Mixed Crystals in the Tetragonal Phase

Raman spectroscopy of optical phonon confinement in nanostructured materials

Contact Info

Product

Resources

About

Model for Long ‐ Wavelength Optical‐Phonon Modes of Mixed Crystals

Cited by 216 publications

References 16 publications

Unification of the phonon mode behavior in semiconductor alloys: Theory andab initiocalculations

Unification of the phonon mode behavior in semiconductor alloys: Theory andab initiocalculations

Raman Scattering Studies on (NH4)Cl1−xBrx Mixed Crystals in the Tetragonal Phase

Raman spectroscopy of optical phonon confinement in nanostructured materials

Contact Info

Product

Resources

About

Raman Scattering Studies on (NH₄)Cl_1−xBr_x Mixed Crystals in the Tetragonal Phase