Phonons and Holes in Magnesium Doped GaN

1998 ◽  
Vol 512 ◽  
Author(s):  
F. Demangeot ◽  
J. Frandon ◽  
M. A. Renucci ◽  
D. Smirnov ◽  
J. Létin ◽  
...  
Keyword(s):  
Experimental Data ◽  
Raman Scattering ◽  
Present Communication ◽  
Electrical Measurements ◽  
Phonon Modes ◽  
Free Hole ◽  
Reflectivity Spectra ◽  
Dielectric Model ◽  
Raman Study ◽  
Silicon Doped

ABSTRACTP doping of gallium nitride by incorporation of magnesium in the layers was controlled recently. Only Popovici et al. [1] have published the results of a Raman study on p type GaN. In the present communication, we report on the interaction of the free hole gas with the axial A1(LO) or planar E1(LO) phonon modes, evidenced by Raman scattering: the observed coupled phononplasmon mode is found very different from the corresponding one evidenced in silicon doped (n type) GaN. We compare the experimental data with the lineshape calculated within a dielectric model, using the results of electrical measurements. These results are also compared with infrared reflectivity spectra.

Optical phonons and its effect on physical properties of rare-earth orthoferrites RFeO3 (R = La, Nd, Gd, Dy, Er): IR reflectivity measurements

2018 ◽  
Vol 32 (21) ◽  
pp. 1850229
Author(s):  
Muhammad Tufiq Jamil ◽  
Javed Ahmad ◽  
Syed Hamad Bukhari ◽  
Hammad Ahmad
Keyword(s):  
Sol Gel ◽  
Structural Evolution ◽  
Electrical Measurements ◽  
Phonon Modes ◽  
Lorentz Oscillator ◽  
Reflectivity Spectra ◽  
Visible Spectra ◽  
Atomic Vibrations ◽  
Uv Visible ◽  
Method Analysis

We have investigated the infrared reflectivity, UV-visible spectra and electrical property of polycrystalline RFeO3 (R = La, Nd, Gd, Dy, Er) synthesized by sol–gel method. Analysis of IR reflectivity spectra through Lorentz oscillator model has led to the observation of 14 IR active phonon modes out of 25 predicted modes. The results have been discussed in terms of different phonon bands related to the origin of atomic vibrations, which provides information about the structural evolution. The energy bandgap [Formula: see text]1.67–1.90 eV estimated from optical conductivity ([Formula: see text]([Formula: see text])) spectrum is found consistent both with that calculated from UV-visible spectra and estimated from electrical measurements.

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.

Characteristic features of Raman scattering of light in silicon doped with high krypton doses

1997 ◽  
Vol 31 (7) ◽  
pp. 669-671
Author(s):  
M. F. Galyautdinov ◽  
N. V. Kurbatova ◽  
S. A. Moiseev ◽  
E. I. Shtyrkov
Keyword(s):  
Raman Scattering ◽  
Scattering Of Light ◽  
Characteristic Features ◽  
Silicon Doped

A density functional theory and resonance Raman study of a benzotriazole dye used in surface enhanced resonance Raman scattering

2006 ◽  
Vol 789 (1-3) ◽  
pp. 59-70 ◽  
Author(s):  
Prokopis C. Andrikopoulos ◽  
Karen M. McCarney ◽  
David R. Armstrong ◽  
Rachael E. Littleford ◽  
Duncan Graham ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Raman Scattering ◽  
Density Functional ◽  
Resonance Raman ◽  
Resonance Raman Scattering ◽  
Functional Theory ◽  
Surface Enhanced ◽  
Raman Study

Dispersion of plasmon-phonon modes in semiconductors: Raman scattering and infrared spectra

1975 ◽  
Vol 16 (2) ◽  
pp. 221-225 ◽  
Author(s):  
V.I. Zemski ◽  
E.L. Ivchenko ◽  
D.N. Mirlin ◽  
Reshina I.I.
Keyword(s):  
Raman Scattering ◽  
Infrared Spectra ◽  
Phonon Modes

The Meyer–Neldel Rule in Conduction Mechanism of the Electrospun ZnO Nanofibers

NANO ◽  
2016 ◽  
Vol 11 (03) ◽  
pp. 1650025 ◽  
Author(s):  
Andrzej Stafiniak ◽  
Marek Tłaczała
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Conduction Mechanism ◽  
Deep Level ◽  
Electrical Measurements ◽  
Thermally Activated ◽  
Theoretical Assumptions ◽  
Different Temperatures ◽  
Zno Nanofibers ◽  
Improved Model

An analytical model describing the conductivity of ZnO nanofibers depending on the grains size is proposed. The research is based on the thermal dc electrical measurements of a single electrospun ZnO nanofiber calcined at different temperatures. In the our previous research, we showed that electrical conduction of ZnO nanofibers is mainly thermally activated. The activation energy of conductivity was strongly dependent on the grain size, which in turn depended on the calcination temperature. This could be due to migration of a point defect in the grain of ZnO and could change the carrier concentration. Our recent studies have shown that ZnO nanofibers behavior is consistent with the Meyer–Neldel rule. This indicates an exponential energy distribution of deep level traps in the material. Based on the theoretical assumptions and experimental data, the improved model of conductivity in a single ZnO nanofiber calcined at different temperatures was proposed.

OPTICAL REFLECTIVITY STUDY ON THE SINGLE CRYSTALLINE (La1−xSrx)2CuO4

1988 ◽  
Vol 01 (09n10) ◽  
pp. 353-361 ◽  
Author(s):  
S. TAJIMA ◽  
S. UCHIDA ◽  
H. ISHII ◽  
H. TAKAGI ◽  
S. TANAKA ◽  
...  
Keyword(s):  
Infrared Spectrum ◽  
Energy Range ◽  
Single Crystal ◽  
Phonon Spectrum ◽  
Wide Energy Range ◽  
Phonon Modes ◽  
Single Crystalline ◽  
Optical Reflectivity ◽  
Reflectivity Spectra ◽  
Wide Energy

The optical reflectivity spectra were measured for single crystalline La2CuO4 and La1.8Sr0.2CuO4 over a wide energy range from 12meV to 3eV. Comparing the phonon spectrum of single crystal with that of polycrystal, the observed four phonon modes can be classified into the two—the vibrations parallel and perpendicular to the c-axis. The infrared spectrum of La1.8Sr0.2CuO4 shows the normal Drude-type behavior without any extra excitation.

ONE-PHONON-ASSISTED ELECTRON RESONANT RAMAN SCATTERING IN FREE-STANDING QUANTUM WIRES

2007 ◽  
Vol 21 (17) ◽  
pp. 2989-3000
Author(s):  
XIANG-FU ZHAO ◽  
CUI-HONG LIU
Keyword(s):  
Raman Scattering ◽  
Quantum Wire ◽  
Quantum Wires ◽  
Longitudinal Optical ◽  
Phonon Modes ◽  
Free Standing ◽  
Surface Optical ◽  
Resonant Raman ◽  
Resonant Raman Scattering ◽  
Valence Bands

The scattering intensity (SI) for an electron resonant Raman scattering (ERRS) process in a free-standing semiconductor quantum wire of cylindrical geometry associated with bulk longitudinal optical (LO) phonon modes or the surface optical (SO) phonon modes is calculated for T=0 K . The Fröhlich interaction is considered to illustrate the theory for a GaAs system. Electron states are confined within a free-standing quantum wire (FSW). Single parabolic conduction and valence bands are assumed. The selection rules are studied. Numerical results and a discussion are also presented for various radii of the cylindrical quantum wires.

STUDIES OF NEW SUPERCONDUCTING Bi-Sr-Ca-Cu-O SYSTEM BY INFRARED AND RAMAN SPECTROSCOPY

1988 ◽  
Vol 02 (05) ◽  
pp. 707-711 ◽  
Author(s):  
JINGQING LIU ◽  
YIFENG YAN ◽  
TANG ZHOU ◽  
GUANGCAN CHE ◽  
DAWEI CHANG ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Absorption Band ◽  
Infrared Spectrum ◽  
Raman Scattering ◽  
Vibrational Mode ◽  
Raman Scattering Spectrum ◽  
Infrared Transmission ◽  
Phonon Modes ◽  
Scattering Spectrum ◽  
Infrared And Raman Spectroscopy

We report both infrared transmission and Raman scattering results on the new superconducting Bi-Sr-Ca-Cu-O system. Because of its layered structure along c axis, some very thin and transparent slices have been got. In the infrared spectrum there is an absorption band around 500cm−1 with a width of about 300cm−1, and a vibrational mode at 840cm−1, higher frequency than those of phonon modes in Y-Ba-Cu-O system, has also been observed. The Raman scattering spectrum shows similar results, but the scattering signals are very weak because of the strong absorption in visible of this system.

The Lifetime of Polar-Optical Modes in Semiconductors

2009 ◽  
Vol 1221 ◽  
Author(s):  
Brian K Ridley ◽  
Angela Dyson
Keyword(s):  
Raman Scattering ◽  
Bulk Material ◽  
Phonon Modes ◽  
High Frequencies ◽  
Power Semiconductor ◽  
Power Semiconductor Devices ◽  
Optical Modes ◽  
Electronic Performance ◽  
Anharmonic Decay

AbstractAn enduring problem in the engineering of high-power semiconductor devices is how to mitigate the effect of heating. Heating means the proliferation of phonons, and phonons, interacting with electrons directly affect the electronic performance of the device. Nowhere is this more evident than the role of hot polar-optical phonons in reducing the drift velocity in the channel of an HFET and hence reducing its performance at high frequencies. The task of describing hot-phonon effects is complicated by the coupling to plasma modes. We present a theory of coupled plasmon-phonon modes in GaN, how they interact with electrons and how their lifetime becomes density-dependent. Raman scattering in bulk material shows a reduction of lifetime with increasing density and we offer an explanation for this in terms of the frequency dependence of the anharmonic decay mechanism. Hot-phonon effects, however, involve modes with wave-vectors beyond those probed by Raman scattering. By adopting a single-pole approximation for these modes we have obtained the lifetime dependence on wave vector, electron temperature and density.

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