Phonon confinement and laser heating effects in Germanium nanowires

2006 ◽  
Vol 74 (15) ◽  
Author(s):  
R. Jalilian ◽  
G. U. Sumanasekera ◽  
H. Chandrasekharan ◽  
M. K. Sunkara
Keyword(s):  
Laser Heating ◽  
Phonon Confinement ◽  
Germanium Nanowires ◽  
Heating Effects

scholarly journals Depth-Resolved Microspectroscopy of Porous Silicon Multilayers

1999 ◽  
Vol 588 ◽  
Author(s):  
S. Manotas ◽  
F. Agulló-Rueda ◽  
J. D. Moreno ◽  
R. J. Martín-Palma ◽  
R. Guerrero-Lemus ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Quantum Confinement ◽  
Silicon Nanocrystals ◽  
Phonon Frequency ◽  
Lattice Mismatch ◽  
High Porosity ◽  
Phonon Confinement ◽  
Heating Effects ◽  
Average Size ◽  
Good Agreement

AbstractWe have measured micro-photoluminescence (PL) and micro-Raman spectra on the cross section of porous silicon multilayers to sample different layer depths. We find noticeable differences in the spectra of layers with different porosity, as expected from the quantum confinement of electrons and phonons in silicon nanocrystals with different average sizes. The PL emission band gets stronger, blue shifts, and narrows at the high porosity layers. The average size can be estimated from the shift. The Raman phonon band at 520 cm−1 weakens and broadens asymmetrically towards the low energy side. The line shape can be related quantitatively with the average size by the phonon confinement model. To get a good agreement with the model we add a band at around 480 cm−1, which has been attributed to amorphous silicon. We also have to leave as free parameters the bulk silicon phonon frequency and its line width, which depend on temperature and stress. We reduced laser power to eliminate heating effects. Then we use the change of frequency with depth to monitor the stress. At the interface with the substrate we find a compressive stress in excess of 10 kbar, which agrees with the reported lattice mismatch. Finally, average sizes are larger than those estimated from PL.

In situmonitoring of Joule heating effects in germanium nanowires by μ-Raman spectroscopy

2013 ◽  
Vol 24 (6) ◽  
pp. 065701 ◽  
Author(s):  
Alois Lugstein ◽  
Mario Mijić ◽  
Thomas Burchhart ◽  
Clemens Zeiner ◽  
Rupert Langegger ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Joule Heating ◽  
Germanium Nanowires ◽  
Heating Effects

Raman scattering of MnOxCeOx composite catalysts: structural aspects and laser-heating effects

2011 ◽  
Vol 42 (7) ◽  
pp. 1583-1588 ◽  
Author(s):  
Barbara Fazio ◽  
Lorenzo Spadaro ◽  
Giuseppe Trunfio ◽  
Jacopo Negro ◽  
Francesco Arena
Keyword(s):  
Raman Scattering ◽  
Laser Heating ◽  
Composite Catalysts ◽  
Heating Effects ◽  
Structural Aspects

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.

Effect of Parameters on Lattice Thermal Conductivity in Germanium Nanowires

2013 ◽  
Vol 832 ◽  
pp. 33-38 ◽  
Author(s):  
S.M. Mamand ◽  
M.S. Omar
Keyword(s):  
Thermal Conductivity ◽  
Low Temperatures ◽  
Lattice Thermal Conductivity ◽  
Phonon Scattering ◽  
Intrinsic Properties ◽  
Phonon Confinement ◽  
Germanium Nanowires ◽  
Transverse Modes ◽  
Experimental Values ◽  
Electron Phonon Scattering

Modified Callaway's theory was used to calculate lattice thermal conductivity (LTC) of Germanium nanowires. Results are compared to those of experimental values of the temperature dependence of LTC for nanowire diameters of 62, 19, and 15nm. In this calculation, both longitudinal and transverse modes are taken into account. Scattering of phonons is assumed to be by nanowire boundaries, imperfections, dislocations, electrons, and other phonons via both normal and Umklapp processes. Effect of parameters, phonon confinement and imperfections in limiting thermal conductivity for the nanowires under considerations are investigated. The suppression in thermal conductivity of these nanowires is arise from electron-phonon scattering and phonon-boundary scattering at low temperatures, while at high temperatures is due to imperfections and intrinsic properties.

Local laser heating effects in monolayer WS2 probed by photoluminescence

2021 ◽  
pp. 150226
Author(s):  
Q. Peng ◽  
C.C. Zheng ◽  
X. Chen ◽  
R.X. Wang ◽  
S.J. Xu ◽  
...  
Keyword(s):  
Laser Heating ◽  
Heating Effects

Laser heating versus phonon confinement effect in the Raman spectra of diamond nanoparticles

2012 ◽  
Vol 14 (6) ◽  
Author(s):  
Marc Chaigneau ◽  
Gennaro Picardi ◽  
Hugues A. Girard ◽  
Jean-Charles Arnault ◽  
Razvigor Ossikovski
Keyword(s):  
Raman Spectra ◽  
Laser Heating ◽  
Confinement Effect ◽  
Phonon Confinement ◽  
Diamond Nanoparticles ◽  
Phonon Confinement Effect
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