OPTICAL VIBRATION MODES IN SPHERICAL CORE-SHELL QUANTUM DOTS

Using a dielectric continuum approach, the optical vibration modes in a spherical core-shell quantum dots (QDs) imbedded in a host nonpolar material are studied. The dispersion relation and the corresponding electron–phonon interaction Hamiltonian are derived. The numerical calculations for the CdSe/ZnS system are performed. The results reveal that there are three branches frequencies of interface/surface optical phonon in the system. A detailed discussion of the combined effects of the spatial confinement and dielectric mismatch between the dot and the host medium is given.

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Effects of ternary mixed crystals on interface/surface optical phonon in spherical core-shell quantum dots

Modern Physics Letters B ◽

10.1142/s0217984919500684 ◽

2019 ◽

Vol 33 (06) ◽

pp. 1950068

Author(s):

Y. Liu ◽

L. P. Liu ◽

Y. Xing ◽

X. X. Liang

Keyword(s):

Mixed Crystals ◽

Core Shell ◽

Phonon Modes ◽

Electron Phonon Interaction ◽

Interface Surface ◽

Photoelectric Properties ◽

Surface Optical ◽

Spherical Core ◽

The One ◽

Dielectric Continuum

Within the framework of the dielectric continuum approach and modified random-element-isodisplacement model, the optical vibration mode in a spherical core-shell quantum dot (CSQD) consisting of ternary mixed crystals (TMCs) are investigated. The dispersion relation and electron–phonon interaction Hamiltonian are derived. As a typical case, the numerical results for [Formula: see text] and [Formula: see text] CSQDs are obtained and discussed. Taking the one- and two-mode behaviors of TMCs into account, the effects of TMCs on interface/surface optical (IO/SO) phonon show that there are 3 and 5 branches of IO/SO phonon modes in [Formula: see text] and [Formula: see text] CSQDs for a given component of TMC, respectively. It is also found that the IO/SO phonon frequencies and electron–phonon interactions are strongly dependent on the component of TMCs and the size of CSQDs. We hope this work would be useful for the study of the phonon-related photoelectric properties in CSQDs consisting of TMCs.

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POLAR VIBRATION SPECTRA OF INTERFACE AND SURFACE OPTICAL PHONONS AND THEIR FRÖHLICH ELECTRON-PHONON INTERACTIONS IN FREESTANDING SYMMETRICAL AND ASYMMETRICAL WURTZITEGaN/Ga1-xAlxNMULTI-LAYER HETEROSTRUCTURES

International Journal of Modern Physics B ◽

10.1142/s0217979206033425 ◽

2006 ◽

Vol 20 (05) ◽

pp. 559-578 ◽

Cited By ~ 3

Author(s):

LI ZHANG ◽

JUN-JIE SHI

Keyword(s):

Quantum Wells ◽

Electrostatic Potential ◽

Uniaxial Crystal ◽

Wave Number ◽

Phonon Modes ◽

Electron Phonon Interaction ◽

Surface Optical ◽

Electron Phonon Coupling ◽

Crystal Model ◽

Dielectric Continuum

Under the dielectric continuum model and Loudon's uniaxial crystal model, by adopting the transfer matrix method, the dispersion properties of the interface optical (IO) and surface optical (SO) phonon modes and their couplings with electrons in multi-layer coupling wurtzite quantum wells (QWs) are deduced and analyzed via the method of electrostatic potential expanding. Numerical calculations on a freestanding symmetrical wurtzite QW and an asymmetrical wurtzite QW have been performed. Results reveal that, in general, there are four branches of IO and two branches of SO phonon modes in the systems. The dispersions of these IO and SO phonon modes are obvious only when the free two-dimensional phonon wave number ktparallel to the heterostructure interfaces is small. The degenerating behavior for these phonon modes has been clearly observed for small kt. When ktis relatively large, with the increase in kt, the frequencies of the IO and SO phonon modes converge to some definite limiting frequencies in corresponding wurtzite single planar heterostructure. This feature have been analyzed in depth from the mathematical and physical viewpoints. The calculations of electron-phonon coupling function show that, the electrostatic potential distribution of the IO and SO mode in freestanding symmetrical wurtzite QW is either symmetrical or is antisymmetrical; but that in freestanding asymmetrical wurtzite QW is neither symmetrical nor is antisymmetric. The calculation also shows that the SO modes and the short wavelength phonon modes play a more important role in the electron-phonon interaction.

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