Characterization of Electrical Properties in SiC Crystals by Raman Scattering Spectroscopy

2008 ◽  
Vol 600-603 ◽  
pp. 501-504 ◽  
Author(s):  
T. Kitamura ◽  
Shinichi Nakashima ◽  
Tomohisa Kato ◽  
K. Kojima ◽  
Hajime Okumura
Keyword(s):  
Electrical Properties ◽  
Raman Scattering ◽  
Shape Analysis ◽  
Line Shape ◽  
Carrier Density ◽  
Peak Frequency ◽  
Bulk Crystals ◽  
Raman Scattering Spectroscopy ◽  
Line Shape Analysis

We characterized the 4H- and 6H-SiC bulk crystals with graded doping and epitaxial films with various carrier densities by Raman scattering spectroscopy. Electrical properties such as free carrier density were examined for the SiC crystals through Raman measurements of the A1 LO-phonon plasmon coupled (LOPC) mode and its line shape analysis. The peak frequency and band width of LOPC mode varied with carrier density in the range from 1016 to 1019 cm-3. The line shape analysis revealed that the carrier density in the SiC crystals can be simply estimated from measured frequency shift of LOPC mode for 4H- and 6H-SiC crystals.

Raman Scattering Analysis of Electrical Property and Crystallinity in Freestanding GaN Crystals with Various Impurity Concentrations

2008 ◽  
Vol 600-603 ◽  
pp. 1293-1296
Author(s):  
T. Kitamura ◽  
Shinichi Nakashima ◽  
Hajime Okumura
Keyword(s):  
Raman Scattering ◽  
Shape Analysis ◽  
Line Shape ◽  
Carrier Density ◽  
Free Carrier ◽  
Raman Scattering Spectroscopy ◽  
Line Shape Analysis ◽  
Free Carrier Density ◽  
Low Dislocation Density ◽  
Shallow Impurity

We characterized the HVPE grown freestanding GaN crystals with various shallow impurity concentrations by Raman scattering spectroscopy. Electrical properties such as free carrier density were examined for the GaN crystals through Raman measurements of the A1 LO-phonon plasmon coupled (LOPC) mode and its line shape analysis. The asymmetric broadening and the up-shift of the LOPC band were clearly observed as the carrier density increased from 1017 to 1019 cm-3. The line shape analysis revealed that the carrier density in the GaN crystals can be simply estimated from measured frequency shift of LOPC mode. The variations of the width for TO phonon bands were also observed in this carrier density range. The band widths were slightly increased by 0.2 cm-1 as the impurity concentration increased from 1018 to 1019 cm-3 in samples with low dislocation density.

Line‐shape analysis of extra resonance signal in coherent Stokes Raman scattering of acridine in the T1 state

1989 ◽  
Vol 91 (4) ◽  
pp. 2030-2035 ◽  
Author(s):  
Toshio Kamisuki ◽  
Kazuhiro Suzuki ◽  
Yukio Adachi ◽  
Shiro Maeda
Keyword(s):  
Raman Scattering ◽  
Shape Analysis ◽  
Line Shape ◽  
Resonance Signal ◽  
Line Shape Analysis

Raman scattering of self-assembled gallium nitride nanorods synthesized by plasma-assisted molecular beam epitaxy

2005 ◽  
Vol 892 ◽  
Author(s):  
D. Wang ◽  
C.-C. Tin ◽  
J. R. Williams ◽  
M. Park ◽  
Y. S. Park ◽  
...  
Keyword(s):  
Residual Stress ◽  
Molecular Beam Epitaxy ◽  
Raman Scattering ◽  
Frequency Shift ◽  
Shape Analysis ◽  
Line Shape ◽  
Molecular Beam ◽  
Local Heating ◽  
Raman Mode ◽  
Line Shape Analysis

AbstractRaman scattering experiment was carried out to study material and electronic properties of the aligned GaN nanorods grown by plasma-assisted molecular beam epitaxy. Due to the small size of the nanorods and the relatively high power density of the laser illumination used in this investigation, local heating of the sample cannot be neglected. Special care has been taken to identify the frequency shift in the optical phonon peaks induced by local heating prior to any spectral analysis. The residual stress in the GaN nanorods was estimated by analyzing the frequency shift of its E2 Raman mode. It was found that the frequency of E2 mode is shifted by only 0.1 cm-1 comparing with the stress-free frequency, indicating a negligible residual stress in nanorods. Owing to aligned geometry of the nanorods and the back-scattering scattering geometry used in the experiment, A1(LO) Raman mode was collected. The free carrier concentration as well as electron mobility of the GaN nanorods were obtained by the line shape analysis of the coupled A1(LO) phonon-plasmon mode. The electron concentration and mobility of electron obtained from line shape analysis are 3.3×1017 cm-3 and 140 cm2/Vs, respectively. We presented a general method of better determining the electronic parameters of the GaN nanostructures via Raman scattering.

RESONANT Lα X-RAY RAMAN SCATTERING SPECTRA OF CeF3, CeO2andCeB6

2002 ◽  
Vol 09 (02) ◽  
pp. 1059-1064 ◽  
Author(s):  
S. NAKAI ◽  
T. WATANABE ◽  
K. SASAKI ◽  
T. IWASAKI ◽  
M. ODAKA ◽  
...  
Keyword(s):  
Absorption Spectrum ◽  
Raman Scattering ◽  
Shape Analysis ◽  
Line Shape ◽  
Emission Spectra ◽  
Edge Region ◽  
X Ray ◽  
Line Shape Analysis ◽  
Scattering Spectra ◽  
Raman Scattering Spectra

Resonant Lα emission spectra of Ce compounds, CeF 3, CeO 2 and CeB 6, were measured around the LIII absorption threshold. As the energy of the incident photon is tuned at the pre-edge region and at the absorption peaks of the Ce LIII absorption spectrum, the Raman peaks are resonantly enhanced. Obtained spectra are decomposed into Raman and normal Lα emission peaks by line shape analysis. The results show that the Raman spectra provide more detailed information than the absorption spectra about the 4f configuration of Ce compounds.

Determination of the Accurate Values of the Rate Constant and Thermodynamic Parameters for the Rotation About the C(sp2)-C(aryl) Bond; Adamantan-1-yl 3-Bromo-2,4,6-trimethylphenyl Ketone

1998 ◽  
Vol 63 (7) ◽  
pp. 955-966
Author(s):  
Eva Přibylová ◽  
Miroslav Holík
Keyword(s):  
Thermodynamic Parameters ◽  
Shape Analysis ◽  
Rate Constants ◽  
Line Shape ◽  
Microsoft Excel ◽  
Hindered Rotation ◽  
H Nmr ◽  
Line Shape Analysis ◽  
Coalescence Temperature

Four programs for the 1H NMR line shape analysis: two commercial - Winkubo (Bruker) and DNMR5 (QCPE 165) and two written in our laboratory - Newton (in Microsoft Excel) and Simtex (in Matlab) have been tested in order to get highly accurate rate constants of the hindered rotation about a single bond. For this purpose four testing criteria were used, two of them were also developed by us. As supplementary determinations the rate constants obtained for the coalescence temperature and for the thermal racemization of chromatographically separated enantiomers were used which fitted well the temperature dependence of the rate constants determined by the line shape analysis. As a test compound adamantan-1-yl 3-bromo-2,4,6-trimethylphenyl ketone was prepared and studied. It was shown that supermodified simplex method used in our algorithm (Simtex), though time consuming, gives the most accurate values of the rate constants and consequently the calculated thermodynamic parameters Ea, ∆H≠, and ∆S≠ lay in relatively narrow confidence intervals.

Sign in / Sign up

Export Citation Format

Share Document