Direct determination of Debye temperature and electron-phonon interaction in1T−VSe2

2001 ◽  
Vol 63 (7) ◽  
Author(s):  
G. V. Kamarchuk ◽  
A. V. Khotkevich ◽  
V. M. Bagatsky ◽  
V. G. Ivanov ◽  
P. Molinié ◽  
...  
Keyword(s):  
Debye Temperature ◽  
Direct Determination ◽  
Phonon Interaction ◽  
Electron Phonon Interaction

scholarly journals Temperature Dependence of G and D’ Phonons in Monolayer to Few-Layer Graphene with Vacancies

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Mingming Yang ◽  
Longlong Wang ◽  
Xiaofen Qiao ◽  
Yi Liu ◽  
Yufan Liu ◽  
...  
Keyword(s):  
Negative Temperature Coefficient ◽  
Negative Temperature ◽  
Intrinsic Properties ◽  
Temperature Dependent ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Layer Graphene ◽  
A Value ◽  
Few Layer Graphene

Abstract The defects into the hexagonal network of a sp2-hybridized carbon atom have been demonstrated to have a significant influence on intrinsic properties of graphene systems. In this paper, we presented a study of temperature-dependent Raman spectra of G peak and D’ band at low temperatures from 78 to 318 K in defective monolayer to few-layer graphene induced by ion C+ bombardment under the determination of vacancy uniformity. Defects lead to the increase of the negative temperature coefficient of G peak, with a value almost identical to that of D’ band. However, the variation of frequency and linewidth of G peak with layer number is contrary to D’ band. It derives from the related electron-phonon interaction in G and D’ phonon in the disorder-induced Raman scattering process. Our results are helpful to understand the mechanism of temperature-dependent phonons in graphene-based materials and provide valuable information on thermal properties of defects for the application of graphene-based devices.

scholarly journals The determination of the electron–phonon interaction from tunneling data in the two-band superconductor MgB2

2004 ◽  
Vol 408-410 ◽  
pp. 353-354 ◽  
Author(s):  
D. Daghero ◽  
R.S. Gonnelli ◽  
G.A. Ummarino ◽  
O.V. Dolgov ◽  
J. Kortus ◽  
...  
Keyword(s):  
Phonon Interaction ◽  
Electron Phonon Interaction

scholarly journals Thermophysical Characterization of Efficiency Droop in GaN-Based Light-Emitting Diodes

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1449
Author(s):  
Tzer-En Nee ◽  
Jen-Cheng Wang ◽  
Bo-Yan Zhong ◽  
Jui-Ju Hsiao ◽  
Ya-Fen Wu
Keyword(s):  
Debye Temperature ◽  
Light Emitting Diodes ◽  
Molar Fraction ◽  
Efficiency Droop ◽  
Multiple Quantum ◽  
Coupling Coefficients ◽  
Phonon Interaction ◽  
Characteristic Ratio ◽  
Light Emitting ◽  
Electron Phonon Interaction

An efficiency droop in GaN-based light-emitting diodes (LED) was characterized by examining its general thermophysical parameters. An effective suppression of emission degradation afforded by the introduction of InGaN/GaN heterobarrier structures in the active region was attributable to an increase in the capture cross-section ratios. The Debye temperatures and the electron–phonon interaction coupling coefficients were obtained from temperature-dependent current-voltage measurements of InGaN/GaN multiple-quantum-well LEDs over a temperature range from 20 to 300 K. It was found that the Debye temperature of the LEDs was modulated by the InN molar fraction in the heterobarriers. As far as the phonons involved in the electron–phonon scattering process are concerned, the average number of phonons decreases with the Debye temperature, and the electron–phonon interaction coupling coefficients phenomenologically reflect the nonradiative transition rates. We can use the characteristic ratio of the Debye temperature to the coupling coefficient (DCR) to assess the efficiency droop phenomenon. Our investigation showed that DCR is correlated to quantum efficiency (QE). The light emission results exhibited the high and low QEs to be represented by the high and low DCRs associated with low and high injection currents, respectively. The DCR can be envisioned as a thermophysical marker of LED performance, not only for efficiency droop characterization but also for heterodevice structure optimization.

Determination of the dilation and vibrational contributions to the temperature shift of excitons in CdS: melting of semiconductors

1982 ◽  
Vol 60 (10) ◽  
pp. 1490-1495 ◽  
Author(s):  
A. Manoogian
Keyword(s):  
Melting Point ◽  
Temperature Shift ◽  
Empirical Method ◽  
Vibrational Amplitude ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Melting Temperatures ◽  
Simple Equations ◽  
Lattice Dilation

An empirical method was used to separate the temperature shift curves of the A- and B-exciton energies in CdS. It was found that the lattice dilation contributed an amount −2.3 × 10−5 eV/K to the temperature shift, and the frequencies of the terms representing the electron–phonon interaction were found to correspond to the average frequencies of the phonons in CdS. The data on the semiconductors analyzed up to now by the empirical method (C, Si, Ge, CdS) were examined at the melting point temperatures of the materials and it was found that the combined results could be described by simple equations. It was found that the r.m.s. vibrational amplitude of the atoms in the above four materials was nearly identical at their melting temperatures.

Tunneling determination of electron-phonon interaction in Mg

1982 ◽  
Vol 90 (9) ◽  
pp. 471-473 ◽  
Author(s):  
D.M. Burnell ◽  
E.L. Wolf
Keyword(s):  
Phonon Interaction ◽  
Electron Phonon Interaction

CORRELATION EFFECTS AND ELECTRON-PHONON INTERACTION IN DOPED FULLERITE

1993 ◽  
Vol 07 (27) ◽  
pp. 1733-1739 ◽  
Author(s):  
VALERY IVANOV ◽  
RENATO PUCCI ◽  
VLADIMIR YARUNIN
Keyword(s):  
Experimental Data ◽  
Electron Scattering ◽  
Low Frequency ◽  
Superconducting Gap ◽  
Correlation Effects ◽  
Phonon Modes ◽  
Phonon Interaction ◽  
Atom Concentration ◽  
Electron Phonon Interaction

We propose a model for A x C 60 systems involving both Hubbard repulsion of alkali electrons in the narrow LUMO band of C 60 and their interaction with both high- and low-frequency phonon modes. In our approach, these phonons play different roles in the determination of a nonzero interband hopping integral hp, which increases the value of the superconductive critical temperature T c . A nonadiabatical approximation is used for the calculation of the soft-phonon-electron scattering. In the framework of the Gor’kov method and the kinematical high-T c mechanism, we have obtained an expression for T c as a function of the A atom concentration x and found that the superconducting gap Δ0 satisfies the inequality 2Δ0/T c >3.53. The qualitative agreements with experimental data were obtained.

The Direct Determination of I131 in Heterogeneous Fecal Specimens

1961 ◽  
Vol 41 (4) ◽  
pp. 380-384 ◽  
Author(s):  
Arthur F. Dratz ◽  
James C. Coberly
Keyword(s):  
Direct Determination
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