Raman scattering from impurities in semiconductors. II. Special cases

1978 ◽  
Vol 56 (5) ◽  
pp. 560-564
Author(s):  
Robert Barrie ◽  
H. -C. Chow
Keyword(s):  
Raman Scattering ◽  
General Result ◽  
Phonon Scattering ◽  
Phonon Coupling ◽  
Strong Electron ◽  
Impurities In Semiconductors ◽  
Electron Phonon Coupling ◽  
Special Cases ◽  
Weak Electron

Special cases of the general result for Raman scattering from an impurity in a semiconductor are discussed. For weak electron–phonon coupling the zero-phonon and one-phonon scattering intensities are derived. For strong electron–phonon coupling a comparison is made between two different approximations that have been previously used.

Raman scattering from impurities in semiconductors. I. General result

1978 ◽  
Vol 56 (5) ◽  
pp. 550-559 ◽  
Author(s):  
Robert Barrie ◽  
I. W. Sharpe
Keyword(s):  
Raman Scattering ◽  
General Result ◽  
Adiabatic Approximation ◽  
Phonon Coupling ◽  
Mathematical Technique ◽  
Impurity Site ◽  
Absorption And Emission ◽  
Systematic Fashion ◽  
Impurities In Semiconductors ◽  
Electron Phonon Coupling

A mathematical technique previously used for studying absorption and emission from impurity centres in semiconductors is applied to Raman scattering from such centres. The usual adiabatic approximation is not made. The method makes use of the fact that at most one electron can be bound at the impurity site and reduces the problem in a systematic fashion to the evaluation of traces over only phonon states. These traces are evaluated for a particular type of electron–phonon coupling.

scholarly journals New Insights into the Role of Weak Electron–Phonon Coupling in Nanostructured ZnO Thin Films

Nanomaterials ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 632 ◽  
Author(s):  
Ashish Gandhi ◽  
Wei-Shan Yeoh ◽  
Ming-An Wu ◽  
Ching-Hao Liao ◽  
Dai-Yao Chiu ◽  
...  
Keyword(s):  
Thin Films ◽  
Raman Scattering ◽  
High Performance ◽  
Zno Thin Films ◽  
Phonon Coupling ◽  
X Ray Diffraction ◽  
Electron Phonon Coupling ◽  
Weak Electron ◽  
Confined System

High-quality crystalline nanostructured ZnO thin films were grown on sapphire substrates by reactive sputtering. As-grown and post-annealed films (in air) with various grain sizes (2 to 29 nm) were investigated by scanning electron microscopy, X-ray diffraction, and Raman scattering. The electron–phonon coupling (EPC) strength, deduced from the ratio of the second- to the first-order Raman scattering intensity, diminished by reducing the ZnO grain size, which mainly relates to the Fröhlich interactions. Our finding suggests that in the spatially quantum-confined system the low polar nature leads to weak EPC. The outcome of this study is important for the development of nanoscale high-performance optoelectronic devices.

Multiphonon Raman Scattering and Strong Electron–Phonon Coupling in 2D Ternary Cu2MoS4 Nanoflakes

2020 ◽  
Vol 11 (20) ◽  
pp. 8483-8489
Author(s):  
Liang Qin ◽  
Zhilin Wen ◽  
Xiaoxian Zhang ◽  
Ke Zhang ◽  
Yunxiang Lin ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Phonon Coupling ◽  
Strong Electron ◽  
Electron Phonon Coupling

scholarly journals Polymerized hybrid perovskites with enhanced stability, flexibility and lattice rigidity

2021 ◽  
Author(s):  
Wenjing Chen ◽  
Yongliang Shi ◽  
Jia Chen ◽  
Pingchuan Ma ◽  
Zhibin Fang ◽  
...  
Keyword(s):  
Phonon Scattering ◽  
Phonon Coupling ◽  
Strong Electron ◽  
Light Emitting ◽  
Electron Phonon Coupling ◽  
External Stresses ◽  
Operation Stability ◽  
Halide Perovskites ◽  
Perovskite Lattice ◽  
Enhanced Stability

Abstract The intrinsic soft lattice nature of organometal halide perovskites (OHPs) makes them very tolerant to defects and ideal candidates for solution-processed optoelectronic devices. However, the soft lattice results in low stability towards external stresses such as heating and humidity, and induces high density of phonons, causing strong electron-phonon coupling. Here, we report solid-state polymerization of OHPs using unsaturated 4-vinylbenzylammonium as organoammonium cations without damaging perovskite structure and its tolerance to defects. The polymerized perovskites show enhanced stability and flexibility. Furthermore, the polymerized 4-vinylbenzylammonium group improves perovskite lattice rigidity substantially, resulting in reduced electron-phonon coupling and non-radiative recombination rate, and enhanced carrier mobility because of suppressed phonon scattering. We finally demonstrate efficient polymerized perovskite based light-emitting diodes with an external quantum efficiency of 23.2% and enhanced operation stability.

scholarly journals Structural phase transition and superconductivity hierarchy in 1T-TaS2 under pressure up to 100 GPa

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Qing Dong ◽  
Quanjun Li ◽  
Shujia Li ◽  
Xuhan Shi ◽  
Shifeng Niu ◽  
...  
Keyword(s):  
Structural Phase ◽  
Transition Metal Dichalcogenides ◽  
Phonon Coupling ◽  
Structural Phase Transitions ◽  
Strong Electron ◽  
Electron Phonon Coupling ◽  
Increasing Trend ◽  
Metal Dichalcogenides ◽  
Dome Shape ◽  
Enhanced Superconductivity

AbstractThe adoption of high pressure not only reinforces the comprehension of the structure and exotic electronic states of transition metal dichalcogenides (TMDs) but also promotes the discovery of intriguing phenomena. Here, 1T-TaS2 was investigated up to 100 GPa, and re-enhanced superconductivity was found with structural phase transitions. The discovered I4/mmm TaS2 presents strong electron–phonon coupling, revealing a good superconductivity of the nonlayered structure. The P–T phase diagram shows a dome shape centered at ~20 GPa, which is attributed to the distortion of the 1T structure. Accompanied by the transition to nonlayered structure above 44.5 GPa, the superconducting critical temperature shows an increasing trend and reaches ~7 K at the highest studied pressure, presenting superior superconductivity compared to the original layered structure. It is unexpected that the pressure-induced re-enhanced superconductivity was observed in TMDs, and the transition from a superconductor with complicated electron-pairing mechanism to a phonon-mediated superconductor would expand the field of pressure-modified superconductivity.

scholarly journals Resonance and antiresonance in Raman scattering in GaSe and InSe crystals

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
M. Osiekowicz ◽  
D. Staszczuk ◽  
K. Olkowska-Pucko ◽  
Ł. Kipczak ◽  
M. Grzeszczyk ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Temperature Effect ◽  
Band Gap ◽  
Raman Spectra ◽  
Quantum Interference ◽  
Optical Band Gap ◽  
Phonon Coupling ◽  
Phonon Modes ◽  
Electron Phonon Coupling ◽  
Resonant Raman

AbstractThe temperature effect on the Raman scattering efficiency is investigated in $$\varepsilon$$ ε -GaSe and $$\gamma$$ γ -InSe crystals. We found that varying the temperature over a broad range from 5 to 350 K permits to achieve both the resonant conditions and the antiresonance behaviour in Raman scattering of the studied materials. The resonant conditions of Raman scattering are observed at about 270 K under the 1.96 eV excitation for GaSe due to the energy proximity of the optical band gap. In the case of InSe, the resonant Raman spectra are apparent at about 50 and 270 K under correspondingly the 2.41 eV and 2.54 eV excitations as a result of the energy proximity of the so-called B transition. Interestingly, the observed resonances for both materials are followed by an antiresonance behaviour noticeable at higher temperatures than the detected resonances. The significant variations of phonon-modes intensities can be explained in terms of electron-phonon coupling and quantum interference of contributions from different points of the Brillouin zone.

scholarly journals Direct observation of excitonic instability in Ta2NiSe5

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Kwangrae Kim ◽  
Hoon Kim ◽  
Jonghwan Kim ◽  
Changil Kwon ◽  
Jun Sung Kim ◽  
...  
Keyword(s):  
Phase Transition ◽  
Direct Observation ◽  
Structural Phase ◽  
Temperature Phase ◽  
Phonon Coupling ◽  
Strong Electron ◽  
Weiss Temperature ◽  
Excitonic Insulator ◽  
Electron Phonon Coupling ◽  
Low Temperature Phase

AbstractCoulomb attraction between electrons and holes in a narrow-gap semiconductor or a semimetal is predicted to lead to an elusive phase of matter dubbed excitonic insulator. However, direct observation of such electronic instability remains extremely rare. Here, we report the observation of incipient divergence in the static excitonic susceptibility of the candidate material Ta2NiSe5 using Raman spectroscopy. Critical fluctuations of the excitonic order parameter give rise to quasi-elastic scattering of B2g symmetry, whose intensity grows inversely with temperature toward the Weiss temperature of TW ≈ 237 K, which is arrested by a structural phase transition driven by an acoustic phonon of the same symmetry at TC = 325 K. Concurrently, a B2g optical phonon becomes heavily damped to the extent that its trace is almost invisible around TC, which manifests a strong electron-phonon coupling that has obscured the identification of the low-temperature phase as an excitonic insulator for more than a decade. Our results unambiguously reveal the electronic origin of the phase transition.

Strong electron-phonon coupling at a metal/organic interface: PTCDA/Ag(111)

2002 ◽  
Vol 65 (12) ◽  
Author(s):  
F. S. Tautz ◽  
M. Eremtchenko ◽  
J. A. Schaefer ◽  
M. Sokolowski ◽  
V. Shklover ◽  
...  
Keyword(s):  
Phonon Coupling ◽  
Strong Electron ◽  
Electron Phonon Coupling ◽  
Metal Organic
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