scholarly journals Probing Phonons in Nonpolar Semiconducting Nanowires with Raman Spectroscopy

2012 ◽  
Vol 2012 ◽  
pp. 1-18 ◽  
Author(s):  
Kofi W. Adu ◽  
Martin D. Williams ◽  
Molly Reber ◽  
Ruwantha Jayasingha ◽  
Humberto R. Gutierrez ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Raman Spectroscopy ◽  
Phenomenological Model ◽  
Line Shape ◽  
Laser Heating ◽  
Acoustic Phonon ◽  
Phonon Confinement ◽  
Semiconducting Nanowires ◽  
Recent Developments ◽  
Raman Probe

We present recent developments in Raman probe of confined optical and acoustic phonons in nonpolar semiconducting nanowires, with emphasis on Si and Ge. First, a review of the theoretical spatial correlation phenomenological model widely used to explain the downshift and asymmetric broadening to lower energies observed in the Raman profile is given. Second, we discuss the influence of local inhomogeneous laser heating and its interplay with phonon confinement on Si and Ge Raman line shape. Finally, acoustic phonon confinement, its effect on thermal conductivity, and factors that lead to phonon damping are discussed in light of their broad implications on nanodevice fabrication.

scholarly journals Thermal conductivity of GaAs nanowires studied by micro-Raman spectroscopy combined with laser heating

2010 ◽  
Vol 97 (26) ◽  
pp. 263107 ◽  
Author(s):  
Martin Soini ◽  
Ilaria Zardo ◽  
Emanuele Uccelli ◽  
Stefan Funk ◽  
Gregor Koblmüller ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Raman Spectroscopy ◽  
Laser Heating ◽  
Micro Raman Spectroscopy ◽  
Gaas Nanowires

scholarly journals Identification of LDPE Grades Focusing on Specific CH2 Raman Vibration Modes

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Richard Jumeau ◽  
Patrice Bourson ◽  
Michel Ferriol ◽  
François Lahure ◽  
Marc Ponçot ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Raman Spectroscopy ◽  
Vibrational Spectroscopy ◽  
Phenomenological Model ◽  
Low Density ◽  
Vibration Modes ◽  
Scanning Calorimetry ◽  
Lamella Thickness ◽  
Poly Ethylene

The possibilities of applications of vibrational spectroscopy techniques (Raman spectroscopy) in the analysis and characterization of polymers are more and more used and accurate. In this paper, our purpose is to characterize Low Density Poly(Ethylene) (LDPE) grades by Raman spectroscopy and in particular with CH2 Raman vibration modes. With temperature measurements, we determine different amorphous and crystalline Raman assignments. From these results and on the basis of the evolution of CH2 bending Raman vibration modes, we develop a phenomenological model in correlation with Differential Scanning Calorimetry and in particular with crystalline lamella thickness determination.

scholarly journals Study of anisotropic thermal conductivity in textured thermoelectric alloys by Raman spectroscopy

RSC Advances ◽  
2021 ◽  
Vol 11 (39) ◽  
pp. 24456-24465
Author(s):  
Rapaka S. C. Bose ◽  
K. Ramesh
Keyword(s):  
Crystal Structure ◽  
Thermal Conductivity ◽  
Raman Spectroscopy ◽  
Transport Properties ◽  
Thermal Transport ◽  
Layered Crystal ◽  
Layered Crystal Structure ◽  
Thermal Transport Properties ◽  
Anisotropic Thermal Conductivity ◽  
P Type

Polycrystalline p-type Sb1.5Bi0.5Te3 (SBT) and n-type Bi2Te2.7Se0.3 (BTS) compounds possessing layered crystal structure show anisotropic electronic and thermal transport properties.

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 Study of Thermometry in Two-Dimensional Sb2Te3 from Temperature-Dependent Raman Spectroscopy

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Manavendra P. Singh ◽  
Manab Mandal ◽  
K. Sethupathi ◽  
M. S. Ramachandra Rao ◽  
Pramoda K. Nayak
Keyword(s):  
Thermal Conductivity ◽  
Raman Spectroscopy ◽  
Temperature Coefficient ◽  
Heat Dissipation ◽  
Peak Position ◽  
Two Dimensional ◽  
Phonon Modes ◽  
Temperature Dependent ◽  
Excellent Candidate ◽  
High Figure

AbstractDiscovery of two-dimensional (2D) topological insulators (TIs) demonstrates tremendous potential in the field of thermoelectric since the last decade. Here, we have synthesized 2D TI, Sb2Te3 of various thicknesses in the range 65–400 nm using mechanical exfoliation and studied temperature coefficient in the range 100–300 K using micro-Raman spectroscopy. The temperature dependence of the peak position and line width of phonon modes have been analyzed to determine the temperature coefficient, which is found to be in the order of 10–2 cm−1/K, and it decreases with a decrease in Sb2Te3 thickness. Such low-temperature coefficient would favor to achieve a high figure of merit (ZT) and pave the way to use this material as an excellent candidate for thermoelectric materials. We have estimated the thermal conductivity of Sb2Te3 flake with the thickness of 115 nm supported on 300-nm SiO2/Si substrate which is found to be ~ 10 W/m–K. The slightly higher thermal conductivity value suggests that the supporting substrate significantly affects the heat dissipation of the Sb2Te3 flake.

Modified phonon confinement model for Raman spectroscopy of nanostructured materials

2010 ◽  
Vol 82 (11) ◽  
Author(s):  
K. Roodenko ◽  
I. A. Goldthorpe ◽  
P. C. McIntyre ◽  
Y. J. Chabal
Keyword(s):  
Raman Spectroscopy ◽  
Nanostructured Materials ◽  
Phonon Confinement ◽  
Confinement Model

Anomalous Heat Conduction, Diffusion and Heat Rectification in Nanoscale Structures

2009 ◽  
Author(s):  
Gang Zhang ◽  
Nuo Yang ◽  
Gang Wu ◽  
Baowen Li
Keyword(s):  
Thermal Conductivity ◽  
Heat Conduction ◽  
Heat Transport ◽  
Nano Materials ◽  
Fourier Law ◽  
Nanoscale Structures ◽  
Recent Developments ◽  
Theoretical Results ◽  
Good Agreement ◽  
Anomalous Heat

In this paper, we report the recent developments in the study of heat transport in nano materials. First of all, we show that phonon transports in nanotube super-diffusively which leads to a length dependence thermal conductivity, thus breaks down the Fourier law. Then we discuss how the introduction of isotope doping can reduce the thermal conductivity efficiently. The theoretical results are in good agreement with experimental ones. Finally, we will demonstrate that nanoscale structures are promising candidates for heat rectification.

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