EFFECTS OF CONFINED LO AND SO PHONON MODES ON POLARON IN FREESTANDING CYLINDRICAL QUANTUM WIRE WITH PARABOLIC CONFINEMENT

2009 ◽  
Vol 23 (29) ◽  
pp. 3515-3523 ◽  
Author(s):  
ANYUN ZOU ◽  
HONGJING XIE
Keyword(s):  
Effective Mass ◽  
Quantum Wire ◽  
Longitudinal Optical ◽  
Perturbation Approach ◽  
Wire Radius ◽  
Phonon Modes ◽  
Phonon Interaction ◽  
Electron Effective Mass ◽  
Self Energy ◽  
Parabolic Confinement

The electron self-energy and correction to the electron effective mass in a freestanding quantum wire with parabolic confining potential was investigated by the perturbation approach. Both the electron-confined longitudinal optical (LO) phonon and surface optical (SO) phonon interactions were considered. Results shows that, for small wire radius, the contributions of electron–LO phonon interaction to the electron self-energy and the correction to the electron effective mass are relatively small in compare with those of the electron–SO phonon interaction.

ONE-PHONON-ASSISTED ELECTRON RESONANT RAMAN SCATTERING IN FREE-STANDING QUANTUM WIRES

2007 ◽  
Vol 21 (17) ◽  
pp. 2989-3000
Author(s):  
XIANG-FU ZHAO ◽  
CUI-HONG LIU
Keyword(s):  
Raman Scattering ◽  
Quantum Wire ◽  
Quantum Wires ◽  
Longitudinal Optical ◽  
Phonon Modes ◽  
Free Standing ◽  
Surface Optical ◽  
Resonant Raman ◽  
Resonant Raman Scattering ◽  
Valence Bands

The scattering intensity (SI) for an electron resonant Raman scattering (ERRS) process in a free-standing semiconductor quantum wire of cylindrical geometry associated with bulk longitudinal optical (LO) phonon modes or the surface optical (SO) phonon modes is calculated for T=0 K . The Fröhlich interaction is considered to illustrate the theory for a GaAs system. Electron states are confined within a free-standing quantum wire (FSW). Single parabolic conduction and valence bands are assumed. The selection rules are studied. Numerical results and a discussion are also presented for various radii of the cylindrical quantum wires.

Electron-Phonon Interaction in a Multi-Shell Spherical Nanoheterosystem

2003 ◽  
Vol 17 (20n21) ◽  
pp. 1081-1094
Author(s):  
Li Zhang ◽  
Hong-Jing Xie ◽  
Chuan-Yu Chen
Keyword(s):  
Longitudinal Optical ◽  
Core Region ◽  
Continuum Approximation ◽  
Phonon Modes ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
The Core ◽  
Dielectric Continuum ◽  
Shell Region

Under the dielectric continuum approximation, the confined longitudinal-optical (LO) phonon and interface-optical (IO) phonon modes of a multi-shell spherical nanoheterosystem are discussed. To describe the vibrations of the LO phonons, a proper eigenfunction for LO phonon modes in the core region is adopted and a legitimate eigenfunction for LO modes in the shell region is constructed. To deal with the IO phonon modes, determinant methods are employed, and the determinant deciding the frequencies of IO phonon modes are obtained. The quantized LO and IO phonons fields as well as their corresponding electron-phonon interaction Hamiltonians are also derived.

ELECTRIC FIELD EFFECTS ON POLARONS WITH SPATIALLY DEPENDENT MASS IN PARABOLIC QUANTUM WELLS

2004 ◽  
Vol 18 (22) ◽  
pp. 2991-2999 ◽  
Author(s):  
FENG-QI ZHAO ◽  
ZI-ZHENG GUO
Keyword(s):  
Electric Field ◽  
Quantum Wells ◽  
Effective Mass ◽  
Energy Levels ◽  
Longitudinal Optical ◽  
Optical Phonons ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Dependent Mass ◽  
Parabolic Quantum Wells

The free polaron energy levels in finite GaAs / Al x Ga 1-x As parabolic quantum wells have been investigated by a modified variational method. The effect of the electric field, the electron-phonon interaction including the longitudinal optical phonons and the four branches of interface optical phonons, and the effect of spatial dependent effective mass have been considered in the calculation. The dependence of the energies of free polarons on the alloy composition x is given. The numerical results for finite GaAs / Al x Ga 1-x As parabolic quantum wells are obtained and discussed. The results show that the effect of the electric field and the interface optical phonons as well as the longitudinal optical phonons on the energy levels is obvious. One can find that the effect of the spatially dependent effective masses on the energy levels in finite parabolic quantum wells is considerable except for large well width. Thus, the electron-phonon interaction and the effect of the spatially dependent effective mass should not be neglected for the study of the electron state problem in finite parabolic quantum wells.

SURFACE POLARON SELF-ENERGY AND EFFECTIVE MASS IN A WURTZITE GaN NANOWIRE

2009 ◽  
Vol 23 (16) ◽  
pp. 3403-3416 ◽  
Author(s):  
LI ZHANG
Keyword(s):  
Effective Mass ◽  
Ground State ◽  
Bulk Material ◽  
Coupling Constants ◽  
Perturbation Approach ◽  
Polar Optical Phonon ◽  
Phonon Coupling ◽  
Phonon Modes ◽  
Self Trapping ◽  
Gan Nanowire

The ground-state self-trapping energy and effective mass of surface polarons in a freestanding wurtzite GaN nanowire (NW) are studied using the second-order perturbation approach. Based on the dielectric continuum and Loudon's uniaxial crystal models, the polar optical phonon modes in the one-dimensional (1D) systems are analyzed, and the vibrating spectra of surface optical (SO) modes and electron–SO phonon coupling functions are discussed and analyzed. The calculations of the ground-state polaron self-trapping energy and the correction of effective mass due to the SO phonon modes in the 1D GaN NWs reveal that the polaron self-trapping energy and the correction of effective mass is far larger than those in 1D GaAs NW systems. The reasons for this obvious difference in the two 1D structures can be attributed to the different electron–phonon coupling constants and electron effective masses of bulk material constituting the two types of 1D confined systems. Finally, the polaronic properties of the wurtzite 1D GaN NWs are compared with those of wurtzite GaN -based two-dimensional quantum wells. The physical origins leading to these characteristics and their distinction in the different-dimensionality systems is carefully analyzed.

scholarly journals Electron, phonon and thermoelectric properties of Cu7PS6 crystal calculated at DFT level

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
B. Andriyevsky ◽  
I. E. Barchiy ◽  
I. P. Studenyak ◽  
A. I. Kashuba ◽  
M. Piasecki
Keyword(s):  
Thermal Conductivity ◽  
Effective Mass ◽  
Thermoelectric Properties ◽  
Density Functional ◽  
Copper Ions ◽  
Boltzmann Transport ◽  
Phonon Modes ◽  
Electron Effective Mass ◽  
Low Thermal Conductivity ◽  
Ion Conducting

AbstractThe promising class of the environment-friendly thermoelectrics is the copper-based argyrodite-type ion-conducting crystals exhibiting just extraordinary low thermal conductivity below the glass limit associated with the molten copper sublattice leading to a softening of phonon modes. To explain why the argyrodite structure containing copper ions favors the low thermal conductivity, we have utilized the ab initio calculations of the electron, phonon, and thermoelectric properties of Cu7PS6 crystal in the framework of the density functional and Boltzmann transport theories. To obtain the reliable thermoelectric properties of Cu7PS6, we take into account the dependence of the electron effective mass m* on the redundant carrier concentration n. We propose to use the Burstein–Moss effect for the calculation of the electron effective mass m* of a semiconductor. We have found the strong nonlinear character of copper atom vibrations in Cu7PS6 which exceeds substantially the similar values for phosphorous and sulfur atoms. The large vibration nonlinearity of the copper atoms found in Cu7PS6 explains the diffusion-like heat transfer and the relatively low coefficient of the lattice thermal conductivity (κ = 0.7 W/(m K)), which is favorable to achieve the large thermoelectric figure of merit.

Electron–Interface–Phonon Interaction and Magnetopolaronic Impurity Transitions in Quantum Wells

1997 ◽  
Vol 11 (08) ◽  
pp. 991-1008 ◽  
Author(s):  
R. Chen ◽  
D. L. Lin
Keyword(s):  
Quantum Wells ◽  
Optical Phonon ◽  
Phonon Frequency ◽  
Transition Energy ◽  
Bulk Sample ◽  
Longitudinal Optical ◽  
Longitudinal Optical Phonon ◽  
Phonon Modes ◽  
Phonon Interaction ◽  
Double Heterostructure

The polaronic effect on the hydrogenic 1s–2p+ transition energy of a donor impurity located at the quantum well center in a double heterostructure is studied theoretically in detail. The electron–optical–phonon interaction Hamiltonian is derived on the basis of eigenmodes of lattice vibrations supported by the double heterostructure. Both the confined and interface phonon modes are included in the electron–phonon coupling. The transition energy is calculated as a function of the applied magnetic field for GaAs/Al 1-x Ga x As samples of well -widths d=125 Å, 210 Å and 450 Å by the second-order perturbation. Wide transition gaps are predicted around the two-level and three-level resonances for all three cases. It is found that the transition gap narrows with the increasing well-width but remains larger than the LO and TO phonon frequency difference for d=450 Å as is observed. We also perform the same calculation by assuming that the confined electron interacts with three-dimensional and two-dimensional phonon modes. The transition energy spectra from these calculations appear to be similar to those for a bulk sample, the spectrum splits at the resonance with the longitudinal optical phonon frequency only. From comparisons of our results with these calculations as well as with experiments, it is conclusively established that the wide gap of transition energy is solely due to the interface modes.

scholarly journals Electron effective mass and phonon modes in GaAs incorporating boron and indium

2007 ◽  
Vol 90 (18) ◽  
pp. 182110 ◽  
Author(s):  
T. Hofmann ◽  
M. Schubert ◽  
G. Leibiger ◽  
V. Gottschalch
Keyword(s):  
Effective Mass ◽  
Phonon Modes ◽  
Electron Effective Mass

SIZE DEPENDENCE OF THE LONGITUDINAL OPTICAL AND SURFACE OPTICAL PHONON MODES IN CYLINDRICAL QUANTUM WIRES

1994 ◽  
Vol 08 (08n09) ◽  
pp. 545-551
Author(s):  
HAI-YANG ZHOU ◽  
SHI-WEI GU
Keyword(s):  
Dispersion Relation ◽  
Optical Phonon ◽  
Quantum Wire ◽  
Size Dependence ◽  
Quantum Wires ◽  
Longitudinal Optical ◽  
Phonon Modes ◽  
Surface Optical ◽  
Macroscopic Approach

With the use of the classical macroscopic approach, we have derived the longitudinal optical (LO) and surface optical (SO) phonon modes in a cylindrical quantum wire (QW). The dispersion relation of the SO phonon modes in the QW is discussed explicitly. Having quantized the vibrational eigenmodes, we give the interaction Hamiltonian of the electron with the LO and SO phonon modes in QW.

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