THE QUASI-CONFINED OPTICAL PHONONS IN WURTZITE SYMMETRY MULTIPLE QUANTUM WELLS

Within the framework of the dielectric-continuum model and Loudon's uniaxial crystal model, the equation of motion for p-polarization field in wurtzite multiplayer symmetry heterostructures are solved for the quasi-confined phonon (QC) modes. The polarization eigenvector, the dispersion relation, and the electron-QC interaction Fröhlich-like Hamiltonian are derived by using the transfer-matrix method. The analytical theory and formulas can be directly applied to the single quantum well (QW) and multiple quantum wells (QWs), and superlattices (SLs). The dispersion relations and the electron-QC coupling strength are investigated for a wurtzite GaN/Al 0.15 Ga 0.85 N single QW. The results show that there are infinite branches of the dispersion curve with definite symmetry with respect to the center of the QW structure. The confinement of the quasi-confined phonons in the QW leads to a quantization of qz,j characterized by an integer m that defines the order of corresponding quasi-confined modes. The QC modes are more dispersive for decreasing m. The QC modes display an interface behavior in the barrier and a confined behavior in the well. When q⊥ is small, the symmetric modes have more contribution to electron-QC interaction than the antisymmetric modes.

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DISPERSION OF THE QUASI-CONFINED OPTICAL PHONONS IN WURTZITE GaN/AlN MULTIPLE QUANTUM WELLS

International Journal of Modern Physics B ◽

10.1142/s0217979207037843 ◽

2007 ◽

Vol 21 (25) ◽

pp. 4407-4418

Author(s):

WEN DENG HUANG ◽

SHU YI WEI ◽

YA JIE REN ◽

YA HUI WANG

Keyword(s):

Quantum Wells ◽

Uniaxial Crystal ◽

Strain Effect ◽

Multiple Quantum ◽

Optical Phonons ◽

Phonon Modes ◽

Crystal Model ◽

Dielectric Continuum ◽

Dielectric Continuum Model ◽

Confined Phonons

Within the framework of the dielectric-continuum model and Loudon's uniaxial crystal model, the dispersions of the quasi-confined optical phonons in arbitrary wurtzite multiplelayer heterostructures are solved by using the transfer-matrix method. The dispersion relations of the quasi-confined phonons are investigated for GaN/AlN single QW and coupled QWs. The confinement of the quasi-confined phonons leads to a quantization of qz, j characterized by an integer m that defines the order of corresponding quasi-confined modes. The quasi-confined modes are more dispersive for decreasing m (i.e., for decreasing qz, j, the bands formed by the dispersion curves are narrower for higher order quasi-confined modes. The strain effect of QW structures has a clear influence on the dispersion behavior of the quasi-confined phonon modes and improves the frequency of the quasi-confined phonons.

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POLAR INTERFACE-OPTICAL VIBRATIONAL SPECTRA IN A WURTZITE GaN/AlN RECTANGULAR QUANTUM WIRE

Surface Review and Letters ◽

10.1142/s0218625x0600786x ◽

2006 ◽

Vol 13 (01) ◽

pp. 75-80 ◽

Cited By ~ 1

Author(s):

L. ZHANG

Keyword(s):

Quantum Wells ◽

Quantum Wire ◽

Quantum Wires ◽

Uniaxial Crystal ◽

Wave Number ◽

Phonon Modes ◽

Crystal Model ◽

Limited Frequency ◽

Dielectric Continuum ◽

Dielectric Continuum Model

Under the dielectric continuum model and Loudon's uniaxial crystal model, the interface optical (IO) phonon modes in a quasi-one-dimensional (Q1D) wurtzite rectangular quantum wire are deduced and analyzed. Numerical calculation on a wurtzite GaN/AlN rectangular wurtzite quantum wire was performed. Results reveal that the dispersion frequencies of IO modes sensitively depend on the geometric structures of the Q1D wurtzite rectangular quantum wires. The degenerating behavior of the IO phonon modes in the Q1D wurtzite rectangular quantum wire has been clearly observed for small free wave number kz in z-direction. The limited frequency behaviors of IO modes have been analyzed deeply, and detailed comparisons with those in wurtzite planar quantum wells and cylindrical quantum wires are also done. Moreover, once the anisotropy of the wurtzite material has been ignored, the present theories can be naturally reduced to the situation of Q1D cubic rectangular quantum wire systems.

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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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GaSb/InGaAsSb/GaSb SINGLE AND MULTIPLE QUANTUM WELLS: OPTICAL PROPERTIES ENGINEERING AND APPLICATION

International Journal of Nanoscience ◽

10.1142/s0219581x07004857 ◽

2007 ◽

Vol 06 (05) ◽

pp. 315-318 ◽

Cited By ~ 4

Author(s):

A. A. KOVALYOV ◽

O. P. PCHELYAKOV ◽

V. V. PREOBRAZHENSKII ◽

M. M. PUTYATO ◽

N. N. RUBTSOVA ◽

...

Keyword(s):

Optical Properties ◽

Quantum Wells ◽

Quantum Confinement ◽

Multiple Quantum Wells ◽

Saturable Absorption ◽

Multiple Quantum ◽

Transmission Spectra ◽

Single Quantum Well ◽

Mbe Growth ◽

High Reflection

MBE growth of GaSb / InGaAsSb / GaSb heterostructures of high crystal quality is performed under continual RHEED control. Transmission spectra of the films forming multiple quantum wells in λ ≈ 2–3 μm region confirm possibility to control optical properties of the structures through quantum confinement and through the content of semiconductor elements. New design of saturable absorption semiconductor mirror (SESAM) for Cr 2+: ZnSe laser is proposed and manufactured on the base of the single quantum well GaSb / InGaAsSb / GaSb placed between dielectric antireflection and broadband high reflection coatings.

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DISPERSION OF INTERFACE OPTICAL PHONONS AND THEIR COUPLING WITH ELECTRONS IN ASYMMETRICAL WURTZITEGaN/Ga1-xAlxNQUANTUM WELLS

Surface Review and Letters ◽

10.1142/s0218625x05007268 ◽

2005 ◽

Vol 12 (03) ◽

pp. 433-442

Author(s):

LI ZHANG ◽

SONG GAO ◽

JUN-JIE SHI

Keyword(s):

Frequency Dispersion ◽

Uniaxial Crystal ◽

Phonon Modes ◽

Phonon Interaction ◽

Electron Phonon Interaction ◽

Electron Phonon Coupling ◽

Crystal Model ◽

Physical Reasons ◽

Dielectric Continuum ◽

Dielectric Continuum Model

Within the framework of the dielectric continuum model and Loudon's uniaxial crystal model, the properties of frequency dispersion of the interface optical (IO) phonon modes and the coupling functions of electron–IO-phonon interaction in an asymmetrical wurtzite quantum well (QW) are deduced and analyzed via the method of electrostatic potential expansion. Numerical results reveal that in general, there are four branches of IO phonon modes in the systems. The dispersions of the four branches of IO phonon modes are obvious only when the free wavenumber ktin xy plane is small. The degenerating behavior of all the four branches of IO phonon modes in the asymmetric wurtzite QWs has been clearly observed for small kt. When ktis relatively large, with the increase of kt, the frequencies of the IO phonon modes converge to the four definite limiting frequencies in the corresponding wurtzite single planar heterostructure. This feature is obviously different from that in symmetric wurtzite QW, and the mathematical and physical reasons have been analyzed in depth. The calculations of electron–phonon coupling function show that the electrostatic distribution of the IO modes is neither symmetrical nor antisymmetrical, and the high-frequency IO phonon branches and the short-wavelength IO phonon modes play a more important role in the electron–phonon interaction.

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