Effect of Nonlinearity Between Raman Shift and Laser Power on the Thermal Conductivity of Graphene Measured by Micro-Raman Spectroscopy

2012 ◽  
Vol 7 (4) ◽  
pp. 395-399 ◽  
Author(s):  
D. P. H. Hasselman ◽  
J. R. Thomas
Keyword(s):  
Thermal Conductivity ◽  
Raman Spectroscopy ◽  
Laser Power ◽  
Raman Shift ◽  
Micro Raman Spectroscopy

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

Measurement of In-Plane Thermal Conductivity of Ultrathin Films Using Micro-Raman Spectroscopy

2014 ◽  
Vol 18 (2) ◽  
pp. 183-193 ◽  
Author(s):  
Zhe Luo ◽  
Han Liu ◽  
Bryan T. Spann ◽  
Yanhui Feng ◽  
Peide Ye ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Raman Spectroscopy ◽  
Ultrathin Films ◽  
Micro Raman Spectroscopy

Laser Flash Raman Spectroscopy Method for Characterizing Thermal Diffusivity of Suspended and Supported 2D Nanomaterials

2016 ◽  
Author(s):  
Qin-Yi Li ◽  
Xing Zhang
Keyword(s):  
Thermal Conductivity ◽  
Raman Spectroscopy ◽  
Thermal Diffusivity ◽  
Laser Power ◽  
2D Materials ◽  
Laser Flash ◽  
Spectroscopy Method ◽  
Measured Temperature ◽  
Laser Absorption ◽  
2D Nanomaterials

2D nanomaterials have been attracting extensive research interests due to their superior properties and the accurate thermophysical characterization of 2D materials is very important for nanoscience and nanotechnology. Recently, a noncontact technique based on the temperature dependent Raman band shifts has been used to measure the thermal conductivity of 2D materials. However, the heat flux, i.e. the absorbed laser power, was either theoretically estimated or measured by a laser power meter with uncertainty, resulting in large errors in thermal conductivity determination. This paper presents a transient “laser flash Raman spectroscopy” method for measuring the thermal diffusivity of 2D nanomaterials in both the suspended and supported forms without knowing laser absorption. Square pulsed laser instead of continuous laser is used to heat the sample and the laser absorption can be eliminated by comparing the measured temperature rises for different laser heating time and laser spot radii. This method is sensitive for characterizing typical 2D materials and useful for nanoscale heat transfer research.

Performance Analysis of Micro-Raman Spectroscopy Models for Thermal Conductivity Calculation

2021 ◽  
Author(s):  
Taher Meydando ◽  
Nazli Donmezer
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Raman Spectroscopy ◽  
Phonon Scattering ◽  
Raman Laser ◽  
Current Approach ◽  
Slab Model ◽  
Boltzmann Transport ◽  
Micro Raman Spectroscopy ◽  
Thermal Conductivities

Abstract Micro-Raman spectroscopy has been preferred recently to measure the thermal conductivity of thin-films due to its nondestructive and non-contact nature. However, the thermal size effects originating from both localized heat generation from Raman laser and phonon scattering at boundaries may cause erroneous estimation of the thermal conductivities with the current approach. In this study, the gray phonon Boltzmann transport equation (BTE) is solved to improve the results of micro-Raman thermal conductivity measurements. Due to the frequency independence of single phonon mode in the gray BTE model, our method stays ahead of most theoretical methods in calculation time while giving adequate agreement with the literature data. The improved thermal conductivities are evaluated at various laser powers and focal lengths. Subsequently, the values of thermal conductivities are compared with a simple slab model in which the deduction of thermal conductivity in sub-micron thicknesses is calculated using reduced heat flux through the slab resulting from phonon directional energy densities. The results show that subsequent errors are present in measuring the thermal conductivity of relatively thick, thin films with this technique which are noticed by comparing with the simple slab model. Finally, a virtual micro-Raman thermography experiment is developed, and its validity is verified by the same slab model.

Dislocation Analysis of 4H-/6H-SiC Single Crystals Using Micro-Raman Spectroscopy

2013 ◽  
Vol 740-742 ◽  
pp. 481-484 ◽  
Author(s):  
Y.J. Shin ◽  
W.J. Kim ◽  
H.Y. Kim ◽  
W. Bahng
Keyword(s):  
Raman Spectroscopy ◽  
Room Temperature ◽  
Dislocation Core ◽  
Raman Shift ◽  
Analysis Method ◽  
Lattice Disorder ◽  
Micro Raman Spectroscopy ◽  
Destructive Analysis ◽  
Measurement Geometry ◽  
Non Destructive

Micro-Raman spectroscopy is an excellent non-destructive analysis method, which compensates for disadvantages of KOH method. Raman shift of A1(LO) and E1(TO) band at threading screw dislocation(TSD) were investigated in n-type on/off-axis 4H- and 6H-SiC single crystal wafers by Micro-Raman scattering at room temperature. The results showed that A1(LO) band were shifted toward higher frequency while the E1(TO) band were shifted toward lower frequency on the on-axis wafers. The shifts are caused by increasing electron concentration and lattice disorder near the dislocation core, respectively. In the off-axis wafers, no shifts were observed possibly due to the measurement geometry which does not contain whole dislocation core.

Study of thermal conductivity in two-dimensional Bi2Te3 from micro-Raman spectroscopy

2021 ◽  
Vol 01 ◽  
Author(s):  
Manavendra P. Singh ◽  
Sumarlang Ryntathiang ◽  
Sivarama Krishnan ◽  
Pramoda K. Nayak
Keyword(s):  
Thermal Conductivity ◽  
Raman Spectroscopy ◽  
Temperature Coefficient ◽  
Raman Spectra ◽  
Heat Dissipation ◽  
Surface States ◽  
Power Coefficient ◽  
Great Promise ◽  
Temperature Dependent ◽  
Micro Raman Spectroscopy

Background: Topological insulator (TI), Bi2Te3 is a new class of the quantum materials. Having ultralow dissipation surface states, TIs hold great promise toward different potential applications. Micro-Raman spectroscopy is a conventional and non-destructive technique, which has been widely used to characterize the structural and electronic properties of the thermoelectric materials. Objective: To study power dependent and temperature dependent Raman spectra of Bi2Te3 nano flakes on SiO2/Si substrate to estimate the temperature coefficient and thermal conductivity of these flakes for possible application of this material in thermoelectrics. Method: Bi2Te3 flakes of different thicknesses were mechanically exfoliated from high quality bulk Bi2Te3 crystal using scotch tape on 300 nm SiO2/ Si substrates. The power dependent and temperature dependent Raman spectra were acquired with the help of HORIBA LabRAM confocal micro-Raman system in a back scattering geometry. Result: . The observed power dependent and temperature dependent Raman spectra of Bi2Te3 nano flakes follow the same trend as discussed in various literatures. From temperature coefficient and power coefficient values, the in plane thermal conductivity has been estimated, which is found to be in the order of 10 2 W/m-K. The enhancement in the thermal conductivity suggests that the underlying substrate significantly affects the heat dissipation of the Bi2Te3 flake based on the coupling strength with Bi2Te3. Conclusion: This work provides a good platform to understand the role of substrate on the thermal conductivity of exfoliated Bi2Te3 nano flakes and this study can be extended to other substrates.

Beyond ultra-high pressure metamorphism: evidence for extremely high pressure conditions during frictional fusion in gigantic landslides using micro-Raman spectroscopy of quartz: the Tsergo Ri (Langtang Himal, Nepal) rockslide

2021 ◽  
Author(s):  
Peter Tropper ◽  
Kurt Krenn ◽  
Diethard Sanders
Keyword(s):  
Raman Spectroscopy ◽  
High Pressure ◽  
Mass Movement ◽  
Planetary Science ◽  
Raman Mode ◽  
Raman Shift ◽  
Glassy Matrix ◽  
Significant Shift ◽  
Micro Raman Spectroscopy ◽  
Quartz Grains

<p>The Tsergo Ri rockslide represents one of the world's biggest rockslides in crystalline rocks (original volume: 10<sup>10</sup> m<sup>3</sup>). The mass movement comprises migmatites, leucogranites, orthogneisses and paragneisses (Weidinger et al. 2014). During mass-wasting, frictionites and microbreccias formed at the base of the rockslide. The frictionite is mainly composed of a glassy matrix containing biotite, quartz, and abundant plagioclase and K-feldspar. Biotite locally shows a transformation to spinel + glass in highly glassy microdomains. Fe-rich layers in the glass indicate melting of biotite-rich layers of the protolith biotite-bearing orthogneiss. Locally, quartz grains are rimmed by a thin layer of SiO<sub>2</sub> glass (lechatelierite).</p><p>Investigations by McMillan et al. (1991) and Kowitz et al. (2013) have shown that shocked quartz shows a shift in the main A1 Raman mode down to lower wavenumbers with increasing pressures. Tropper et al. (2017) and Sanders et al. (2020) found that quartz from the frictionites in the Köfels landslide (Austria) shows a significant shift of up to 4 cm<sup>-1</sup> in the main A1 Raman mode. Therefore micro-Raman spectroscopy was applied to quartz crystals with and without lechatelierite rims in the Tsergo Ri frictionites. Raman maps of quartz grain areas were prepared using a HORIBA Jobin Yvon LabRam HR800 micro-spectrometer equipped with a 30 mW He-Ne laser (633 nm emission).</p><p>Micro-Raman spectroscopy of 'normal' quartz yielded an intense A1 Raman mode at 464 cm<sup>-1</sup>, whereas<sup>  </sup>quartz without lechatelierite rims shows a shift of this band down to 461.5 cm<sup>-1</sup>. The highest shifts down to 460.5 cm<sup>-1</sup> were observed in quartz grains rimmed by lechatelierite. It is also noteworthy that these grains show an internal gradient of Raman shift of up to 3 cm<sup>-1</sup> from the core (463.5 cm<sup>-1</sup>) to the rim (460.5 cm<sup>-1</sup>) to just below the lechatelierite rims. This is an important observation since lechatelierite formation in frictionites from rockslides was considered so far to be a function of temperature only. Because lechatelierite only rims quartz with strongly shifted A1 band numbers, we interpret lechatelierite formation to be driven by both temperature and pressure, at least under frictionite conditions. The completely molten granitic matrix and the breakdown of biotite to spinel + melt indicates minimum temperatures of 900-1000°C. Sanders et al. (2020) showed that the shifted A1 mode of quartz is stable only below 1100°C, thus giving an upper limit of the temperature range. The observed Raman shift of the A1 mode and the presence of lechatelierite strongly suggest that a pressure of possibly >24-26 GPa was attained (cf. McMillan et al. 1991, Kowitz et al. 2013). The data from Köfels and Tsergo Ri provide the first quantitative estimates of peak pressures during frictionite formation, and show that UHP-modified quartz associated with lechatelierite is common in landslides of silica-rich rocks.</p><p> </p><p> </p><p>References:</p><p>Kowitz et al. 2013: Earth and Planetary Science Letters, 384:17</p><p>McMillan et al. 1992: Physics and Chemistry of Minerals, 19:71</p><p>Sanders et al. 2020: EGU2020-4831</p><p>Tropper et al. 2017: Mitteilungen der Österreichischen Mineralogischen Gesellschaft, 163: 89</p><p>Weidinger et al. 2014: Earth and Planetary Science Letters, 389:62</p>

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