Effect of point defects on the decay of the longitudinal optical mode

2002 ◽  
Vol 316-317 ◽  
pp. 413-416 ◽  
Author(s):  
P.G. Klemens
Keyword(s):  
Point Defects ◽  
Longitudinal Optical ◽  
Optical Mode ◽  
Longitudinal Optical Mode

Experimental detection of collective modes In a polar liquid: application to the case of the solvated electron in H2O and NH3

1977 ◽  
Vol 55 (11) ◽  
pp. 1916-1919 ◽  
Author(s):  
Gianni Ascarelli
Keyword(s):  
Ionic Crystal ◽  
Collective Mode ◽  
Continuum Theory ◽  
Longitudinal Optical ◽  
Collective Modes ◽  
Coupling Constant ◽  
Optical Mode ◽  
Solvated Electron ◽  
Low Frequencies ◽  
Longitudinal Optical Mode

We present experimental data that confirm the predicted existence of a collective mode in a liquid corresponding to the longitudinal optical mode in an ionic crystal. The experimental investigation was carried out in nitromethane, and the results bear out all the calculated properties of this collective mode: the dipolar plasmon. The calculated frequency of the dipolar plasmon, as well as the dielectric constant at high and low frequencies, are then used to calculate without adjustable parameters the polaron coupling constant of the solvated electron in NH3 and H2O. A comparison of the calculated and measured properties of the solvated electron indicates that in either case a polaron-like continuum theory can at most account for only a fraction of the energy of the observed optical absorption.

Redshift ofA1(longitudinal optical) mode for GaN crystals under strong electric field

2017 ◽  
Vol 11 (1) ◽  
pp. 011002 ◽  
Author(s):  
Hong Gu ◽  
Kaijie Wu ◽  
Shunan Zheng ◽  
Lin Shi ◽  
Min Zhang ◽  
...  
Keyword(s):  
Electric Field ◽  
Strong Electric Field ◽  
Longitudinal Optical ◽  
Optical Mode ◽  
Longitudinal Optical Mode

Mechanisms of Raman Scattering in doped Indium Nitride

2004 ◽  
Vol 831 ◽  
Author(s):  
Claire Pinquier ◽  
François Demangeot ◽  
Jean Frandon ◽  
Miguel Gaio ◽  
Olivier Briot ◽  
...  
Keyword(s):  
Light Scattering ◽  
Raman Scattering ◽  
Charge Density ◽  
Dielectric Function ◽  
Density Fluctuation ◽  
Indium Nitride ◽  
Longitudinal Optical ◽  
Optical Mode ◽  
Longitudinal Optical Mode ◽  
Strong Mode

ABSTRACTHighly n-doped InN layers are investigated by means of Raman scattering: a strong mode is evidenced near the frequency of the A1(LO) phonon, despite the high conductivity of the films. This observation is interpreted assuming the breakdown of the wave-vector conservation leading to the decoupling of the plasmon from the phonon. The lineshape of the longitudinal optical mode is simulated using the Lindhard-Mermin dielectric function for various light scattering processes: we found that the charge density fluctuation mechanism is dominant, at least in the visible excitation range.

The Effects of Substrate Bias and Si Doping on the Properties of Rf Sputtered Bn Films

1992 ◽  
Vol 242 ◽  
Author(s):  
P.K. Banerjee ◽  
J.S. Kim ◽  
B. Chatterjee ◽  
M. Platek ◽  
S.S. Mitra
Keyword(s):  
Boron Nitride ◽  
Longitudinal Optical ◽  
Substrate Bias ◽  
Optical Mode ◽  
Linear Change ◽  
Temperature Range ◽  
Ir Transmission ◽  
Si Doped ◽  
Reflectivity Data ◽  
Boron Nitride Films

ABSTRACTThe effect of substrate bias on the properties of rf sputtered boron nitride films on Si and GaAs substrate were investigated. IR transmission and reflectivity of films with different substrate bias were measured with Perkin Elmer 983 IR spectroscopy. From the IR reflectivity data, transverse optical mode(TO) and longitudinal optical mode(LO) frequencies were derived by fitting Kramer-Kronig model. Absorption coefficient was determined from IR transmission data. The resultant TO and LO modes showed that substrate bias caused broadening of reststrahlen band of rf sputtered boron nitride. We also tried to dope boron nitride films with silicon by alternate sputtering of BN and Si targets controlling sputtering time of each target followed by annealing. Electrical resistivity was measured over the temperature range between 175 K to 370 K for both intrinsic and Si-doped boron nitride films. Intrinsic rf sputtered boron nitride showed Little change in resistivity (109 Ω cm - 1011 Ω cm ) over the temperature range studied. While Si doped BN showed linear change in resistivity with increasing temperature and its activation energy was about 0.22 eV. The effect of substrate bias was also investigated by monitoring the XPS core level spectra of both Bis and N Is peaks, respectively. Substrate bias caused the shift of both B ls and N ls peak to higher binding energy. The effect of substrate bias on refractive index was also studied.

scholarly journals Broadband Terahertz Spectroscopy of Phonon-Polariton Dispersion in Ferroelectrics

Photonics ◽  
2018 ◽  
Vol 5 (4) ◽  
pp. 55 ◽  
Author(s):  
Seiji Kojima
Keyword(s):  
Electromagnetic Waves ◽  
Terahertz Spectroscopy ◽  
Far Infrared ◽  
Longitudinal Optical ◽  
Vibrational Modes ◽  
Terahertz Time Domain Spectroscopy ◽  
Raman Scattering Spectroscopy ◽  
Longitudinal Optical Mode ◽  
Relationship Of ◽  
The Relationship

Electromagnetic waves at frequencies below the X-ray region strongly couple to the optical vibrational modes in a solid. These coupled excitations have been called phonon polaritons. The relationship of the polariton frequency versus the polariton wavevector shows a remarkable dispersion, especially in the vicinity of the transverse and longitudinal optical mode frequencies. The significant frequency dependence enables valuable applications such as a tunable terahertz radiation source. The polariton dispersion relations of technologically important dielectric and ferroelectric crystals were reviewed in the broad terahertz range using terahertz time-domain spectroscopy, far-infrared spectroscopy, and Raman scattering spectroscopy.

On determination of properties of ultrathin and very thin silicon oxide layers by FTIR and X - ray reflectivity

2008 ◽  
Vol 1066 ◽  
Author(s):  
Martin Kopani ◽  
Matej Jergel ◽  
Hikaru Kobayashi ◽  
Masao Takahashi ◽  
Robert Brunner ◽  
...  
Keyword(s):  
Absorption Band ◽  
Silicon Oxide ◽  
Layer Structure ◽  
Longitudinal Optical ◽  
Silicon Matrix ◽  
Oxide Layers ◽  
X Ray ◽  
Longitudinal Optical Mode ◽  
Complete Set

ABSTRACTWe analyze properties of ultra-thin SiO2 + very thin SiOx double layer structure formed on high-doped n-type Si (100) wafers using FTIR, X-ray reflectivity and AFM methods. The observed absorption band around 1230 cm−1 is attributed to the longitudinal optical mode of SiOx precipitates incorporated in silicon matrix. In particular, the corresponding peak positions indicate that there are precipitates of SiOx with x >1.8. The absorption band around 1070 cm−1 is attributed to the Si–O–Si stretching bond. This position is characteristic for stoichiometric SiO2. From the results it can be concluded that differently shaped particles co-exist in the samples. This assumption is supported by the oxide density measurements performed by FTIR and X-ray reflectivity. We determined density of oxide layers, roughness of corresponding interfaces, and surface roughness by the X-ray reflectivity. The obtained values were compared with those determined by FTIR and AFM. Additionally, we present the results of multifractal analysis on a complete set of six samples.

Sign in / Sign up

Export Citation Format

Share Document