Acoustic phonon modes of free-standing rectangular wires

1997 ◽  
Vol 22 (2) ◽  
pp. 213-216 ◽  
Author(s):  
Norihiko Nishiguchi ◽  
Yoshihiro Ando ◽  
Martin N. Wybourne
Keyword(s):  
Acoustic Phonon ◽  
Phonon Modes ◽  
Free Standing

scholarly journals Study of confined coherent acoustic phonon modes in a free-standing cubic GaN membrane by femtosecond spectroscopy

2015 ◽  
Vol 107 (11) ◽  
pp. 112105 ◽  
Author(s):  
Chuan He ◽  
Martin Grossmann ◽  
Delia Brick ◽  
Martin Schubert ◽  
Sergei V. Novikov ◽  
...  
Keyword(s):  
Acoustic Phonon ◽  
Femtosecond Spectroscopy ◽  
Phonon Modes ◽  
Free Standing ◽  
Cubic Gan ◽  
Coherent Acoustic Phonon

scholarly journals Universality in electron–modulated-acoustic-phonon interactions in a free-standing semiconductor nanowire

2010 ◽  
Vol 51 (7-8) ◽  
pp. 880-887 ◽  
Author(s):  
Junichi Hattori ◽  
Shigeyasu Uno ◽  
Nobuya Mori ◽  
Kazuo Nakazato
Keyword(s):  
Acoustic Phonon ◽  
Free Standing ◽  
Semiconductor Nanowire

Quantized Acoustic-Phonon Modes in Metallic Nanowire Structures

2015 ◽  
Vol 44 (12) ◽  
pp. 3019-3022 ◽  
Author(s):  
Hou Yuexia ◽  
Xu Wen ◽  
Hu Jiaguang ◽  
Xiao Yiming
Keyword(s):  
Acoustic Phonon ◽  
Phonon Modes

Guided Acoustic Phonon Modes in Layered Anisotropic Nanowires

2003 ◽  
Author(s):  
Osama M. Mukdadi ◽  
Subhendu K. Datta ◽  
Martin L. Dunn
Keyword(s):  
Thermal Conductivity ◽  
Acoustic Phonon ◽  
Energy Transport ◽  
Bulk Material ◽  
Rectangular Cross Section ◽  
Critical Role ◽  
Acoustic Phonons ◽  
Phonon Modes ◽  
Low Velocity ◽  
Analysis Technique

Acoustic phonons play a critical role in energy transport in nanostructures. The dispersion of acoustic phonons strongly influences thermal conductivity. Recent observations show lower values of thermal conductivity in finite dimensional nanostructures than in the bulk material. In this work, we will present results for guided acoustic phonon modes in (a) a bilayered GaAs-Nb nanowire of rectangular cross section and (b) a trapezoidal Si nanowire. The former has been used for phonon counting in a nanocalorimeter for measuring thermal conductivity and the latter is commonly used in MEMS applications. A semi-analytical finite element (SAFE) analysis technique has been used to investigate the effects of layering, anisotropy, and boundaries on the dispersion of modes of propagation. Many interesting features of group velocities are found that show confinements around the corners, in the low velocity layer, and coupling of the longitudinal and flexural modes. These would strongly influence thermal conductivity and might provide means of nondestrutive evaluation of mechanical properties.

scholarly journals Acoustic phonon lifetimes limit thermal transport in methylammonium lead iodide

2018 ◽  
Vol 115 (47) ◽  
pp. 11905-11910 ◽  
Author(s):  
Aryeh Gold-Parker ◽  
Peter M. Gehring ◽  
Jonathan M. Skelton ◽  
Ian C. Smith ◽  
Dan Parshall ◽  
...  
Keyword(s):  
Lattice Dynamics ◽  
Acoustic Phonon ◽  
Optoelectronic Devices ◽  
High Energy ◽  
High Energy Resolution ◽  
Phonon Coupling ◽  
Lead Iodide ◽  
Phonon Modes ◽  
Electron Phonon Coupling ◽  
Methylammonium Lead Iodide

Hybrid organic–inorganic perovskites (HOIPs) have become an important class of semiconductors for solar cells and other optoelectronic applications. Electron–phonon coupling plays a critical role in all optoelectronic devices, and although the lattice dynamics and phonon frequencies of HOIPs have been well studied, little attention has been given to phonon lifetimes. We report high-precision momentum-resolved measurements of acoustic phonon lifetimes in the hybrid perovskite methylammonium lead iodide (MAPI), using inelastic neutron spectroscopy to provide high-energy resolution and fully deuterated single crystals to reduce incoherent scattering from hydrogen. Our measurements reveal extremely short lifetimes on the order of picoseconds, corresponding to nanometer mean free paths and demonstrating that acoustic phonons are unable to dissipate heat efficiently. Lattice-dynamics calculations using ab initio third-order perturbation theory indicate that the short lifetimes stem from strong three-phonon interactions and a high density of low-energy optical phonon modes related to the degrees of freedom of the organic cation. Such short lifetimes have significant implications for electron–phonon coupling in MAPI and other HOIPs, with direct impacts on optoelectronic devices both in the cooling of hot carriers and in the transport and recombination of band edge carriers. These findings illustrate a fundamental difference between HOIPs and conventional photovoltaic semiconductors and demonstrate the importance of understanding lattice dynamics in the effort to develop metal halide perovskite optoelectronic devices.

Acoustic Phonon Lifetimes and Thermal Transport in Free-Standing and Strained Graphene

Nano Letters ◽  
2012 ◽  
Vol 12 (6) ◽  
pp. 2673-2678 ◽  
Author(s):  
Nicola Bonini ◽  
Jivtesh Garg ◽  
Nicola Marzari
Keyword(s):  
Thermal Transport ◽  
Acoustic Phonon ◽  
Free Standing ◽  
Strained Graphene

Excitation and detection of surface acoustic phonon modes inAu/Al2O3multilayers

2009 ◽  
Vol 80 (16) ◽  
Author(s):  
A. Halabica ◽  
S. T. Pantelides ◽  
R. F. Haglund ◽  
R. H. Magruder ◽  
A. Meldrum
Keyword(s):  
Acoustic Phonon ◽  
Phonon Modes

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.

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