共查询到20条相似文献,搜索用时 31 毫秒
1.
J.-M. Liu N. Chong H.L.W. Chan K.H. Wong C.L. Choy 《Applied Physics A: Materials Science & Processing》2003,76(1):93-96
Epitaxial (001) aluminum nitride (AlN) thin films on (111) Si substrates are prepared using pulsed-laser deposition. The epitaxial
structure of the as-prepared thin films is characterized by checking the X-ray-diffraction θ-2 θ scan and pole-figure, using
scanning electron microscopy, infrared radiation (IR) spectroscopy and Raman spectroscopy. The surface acoustic-wave resonance
at 345 MHz for a 1.5 μm thick AlN film on a (111) Si substrate is observed using an inter-digital electrode.
Received: 18 September 2001 / Accepted: 29 January 2002 / Published online: 3 June 2002
RID="*"
ID="*"Corresponding author. Fax: +86-25/359-5535, E-mail: liujm@nju.edu.cn 相似文献
2.
Investigation of size-driven phase transition in bismuth titanate nanocrystals by Raman spectroscopy 总被引:2,自引:0,他引:2
Y.L. Du M.S. Zhang Q. Chen Z. Yin 《Applied Physics A: Materials Science & Processing》2003,76(7):1099-1103
Raman spectroscopy was used to investigate the lattice dynamics and structural transformations in bismuth titanate (Bi4Ti3O12) nanocrystals prepared by a chemical coprecipitation technique. The crystal structure of the samples of different grain sizes
was determined by X-ray-diffraction analysis. The evolution of the Raman spectrum with grain size was characterized by an
intensity decrease, a broadening of the line width, a frequency shift, and the disappearance of the Raman mode. The results
revealed the appearance of a size-driven phase transition from orthorhombic to tetragonal phases at a critical size of 44 nm.
This result is quite consistent with the X-ray-diffraction measurement and differential thermal analysis. The origin was attributed
to the grain-size effect and explained by the surface-energy mechanism.
Received: 26 June 2002 / Accepted: 18 August 2002 / Published online: 15 January 2003
RID="*"
ID="*"Corresponding author. Fax: +86-25/3595535, E-mail: msz@nju.edu.cn 相似文献
3.
T. Ruf 《Applied Physics A: Materials Science & Processing》2003,76(1):21-26
Inelastic X-ray scattering with meV resolution has recently become available for studies of dynamical properties and elementary
excitations in solids. Contrary to Raman spectroscopy at visible wavelengths, which in first order is limited to the Brillouin-zone
center, the wave vectors in hard X-ray Raman scattering are very large, and the crystal-momentum transfer to elementary excitations,
whose energies may range from a few meV up to several eV, can be tuned continuously across the whole Brillouin zone. This
paper reviews new and unique possibilities offered by X-ray Raman spectroscopy for crystalline solids, such as phonon-dispersion
measurements (GaN), the determination of phonon self-energies (isotopically mixed diamond), and resonance effects and studies
of electronic excitations (copper oxides).
Received: 19 October 2001 / Accepted: 12 December 2001 / Published online: 27 March 2002 / Published online: 27 March 2002
RID="*"
ID="*"Present address: Agilent Technologies Deutschland GmbH, Herrenberger Str. 130, 71034 B?blingen, Germany 相似文献
4.
G. Abstreiter E. Bauser A. Fischer K. Ploog 《Applied Physics A: Materials Science & Processing》1978,16(4):345-352
It is shown that Raman spectroscopy can provide useful information on characteristic properties of thin crystalline films
of compound semiconductors. Crystal orientation, carrier concentration, scattering times of charge carriers, composition of
mixed crystals and depth profiles can be studied in thin layers and heterostructures of GaAs and AlxGa1−xAs. The advantages and disadvantages of Raman scattering compared to conventional characterization methods are discussed. 相似文献
5.
Mathias Steiner Marcus Freitag James C. Tsang Vasili Perebeinos Ageeth A. Bol Antonio V. Failla Phaedon Avouris 《Applied Physics A: Materials Science & Processing》2009,96(2):271-282
We study the optical properties of a single, semiconducting single-walled carbon nanotube (CNT) that is partially suspended
across a trench and partially supported by a SiO2-substrate. By tuning the laser excitation energy across the E
33 excitonic resonance of the suspended CNT segment, the scattering intensities of the principal Raman transitions, the radial
breathing mode (RBM), the D mode and the G mode show strong resonance enhancement of up to three orders of magnitude. In the
supported part of the CNT, despite a loss of Raman scattering intensity of up to two orders of magnitude, we recover the E
33 excitonic resonance suffering a substrate-induced red shift of 50 meV. The peak intensity ratio between G band and D band
is highly sensitive to the presence of the substrate and varies by one order of magnitude, demonstrating the much higher defect
density in the supported CNT segments. By comparing the E
33 resonance spectra measured by Raman excitation spectroscopy and photoluminescence (PL) excitation spectroscopy in the suspended
CNT segment, we observe that the peak energy in the PL excitation spectrum is red-shifted by 40 meV. This shift is associated
with the energy difference between the localized exciton dominating the PL excitation spectrum and the free exciton giving
rise to the Raman excitation spectrum. High-resolution Raman spectra reveal substrate-induced symmetry breaking, as evidenced
by the appearance of additional peaks in the strongly broadened Raman G band. Laser-induced line shifts of RBM and G band
measured on the suspended CNT segment are both linear as a function of the laser excitation power. Stokes/anti-Stokes measurements,
however, reveal an increase of the G phonon population while the RBM phonon population is rather independent of the laser
excitation power. 相似文献
6.
W.J. Zhang C.Y. Chan K.M. Chan I. Bello Y. Lifshitz S.T. Lee 《Applied Physics A: Materials Science & Processing》2003,76(6):953-955
Large-area, 1-μm-thick cubic boron nitride (cBN) films were deposited on (001) silicon substrates by electron-cyclotron-resonance-enhanced
microwave-plasma chemical vapor deposition (ECR-MP CVD) in a mixture of He-Ar-N2-BF3-H2 gases. With the assistance of fluorine chemistry in the gas phase and substrate reactions, the phase purity of the sp3-configuration was improved to over 85% at a reduced substrate bias voltage of -40 V. The grown films show clear Raman transversal
optical (TO) and longitudinal optical (LO) phonon vibration modes, characteristic of cBN. Such Raman spectral characteristics
are the first ever observed in cBN films prepared under ECR-MP CVD conditions.
Received: 3 May 2002 / Accepted: 7 May 2002 / Published online: 22 November 2002
RID="*"
ID="*"Corresponding author. Fax: +852-2788/7830, E-mail: apwjzh@cityu.edu.hk 相似文献
7.
Manganese oxide (hausmannite) nanowires were prepared by annealing precursor powders at a temperature of 800 °C for 3 h, which
were produced in a novel inverse microemulsion (IμE) system. The microstructures of the as-prepared Mn3O4 nanowires were investigated by means of X-ray diffraction, transmission electron microscopy, and Raman spectra. It has been
found that the Mn3O4 nanowires were relatively straight and their surfaces were smooth with a typical diameter of 75–150 nm. The formation mechanism
of the Mn3O4 nanowires is discussed.
Received: 30 May 2002 / Accepted: 7 October 2002 / Published online: 17 December 2002
RID="*"
ID="*"Corresponding author. Fax: +86-25/359-5535, E-mail: wangqun@nju.edu.cn 相似文献
8.
W. Wang Z. Liu Y. Liu C. Xu C. Zheng G. Wang 《Applied Physics A: Materials Science & Processing》2003,76(3):417-420
Using a simple wet-chemical route, we synthesized CuO nanorods with diameters of ca. 5–15 nm and lengths of up to 400 nm.
The purity, crystallinity, morphology, structure features, and chemical composition of the as-prepared CuO nanorods were investigated
by powder X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron
spectroscopy, and Raman spectroscopy.
Received: 22 March 2002 / Accepted: 12 June 2002 / Published online: 28 October 2002
RID="*"
ID="*"Corresponding author. Fax: +86-25/359-5535, E-mail: wangqun@nju.edu.cn 相似文献
9.
Abstract: The relation between Raman scattering, resonance Raman scattering, and absorption is reviewed to determine to what extent quantitative analysis can be applied in resonance Raman spectroscopy. In addition, it is demonstrated experimentally that normal Raman spectra can be dramatically inhibited by absorption and resonance Raman effects. Raman spectra of toluene and heptane mixtures—with progressively increasing concentrations of heptane—were measured using 229-nm laser excitation. The results show that the characteristic band intensities are not directly proportional to the relative concentrations of the compounds and deviate due to absorption resonance effects. An approximated mathematical model is developed to demonstrate that the intensities of the normal Raman scattering bands are suppressed. An inhibition coefficient Ki is introduced to describe the situation and determine the penetration depth. Most remarkably, it is shown that the intensity of the resonance Raman scattering bands can be constant even when the concentration ratios differ substantially in the sampled mixtures. 相似文献
10.
M.Y. Goulkov T. Granzow U. Dörfler T. Woike M. Imlau R. Pankrath 《Applied physics. B, Lasers and optics》2003,76(4):407-416
We study light-induced scattering (beam-fanning) in the photorefractive crystal SBN:Ce as a function of the polar structure
of the crystal. The spatial structure of the beam-fanning is measured at different externally applied electric fields, and
an optical hysteresis is found in the scattering. It is shown that the scattering hysteresis results from a polarization hysteresis
typical for ferroelectrics in the polar phase. New information about primary scattering in SBN is obtained, and a corresponding
model of its origin is proposed. It is shown that the intensity and angular distribution of the primary scattering strongly
depend on the polar structure of the crystal and can be affected by the subsequent action of an external field and coherent
illumination.
Received: 27 August 2002 / Revised version: 19 December 2002 / Published online: 26 March 2003
RID="*"
ID="*"Corresponding author. E-mail: mirco.imlau@uni-osnabrueck.de 相似文献
11.
N. Esser 《Applied Physics A: Materials Science & Processing》1999,69(5):507-518
Only recently Raman spectroscopy (RS) has advanced into the study of surface phonons from clean and adsorbate-covered semiconductor
surfaces. RS allows the determination of eigenfrequencies as well as symmetry selection rules of surface phonons, by k-conservation limited to the Brillouin zone-center, and offers a significantly higher spectral resolution than standard surface
science techniques such as high-resolution electron energy loss spectroscopy. Moreover, surface electronic states become accessible
via electron–phonon coupling. In this article the fundamentals of Raman scattering from surface phonons are discussed and
its potential illustrated by considering two examples, namely Sb-monolayer-terminated and clean InP(110) surfaces. Both are
very well understood with respect to their atomic and electronic structure and thus may be regarded as model systems for heteroterminated
and clean semiconductor surfaces. In both cases, localized surface phonons as well as surface resonances are detected by Raman
spectroscopy. The experimental results are compared with surface modes predicted by theoretical calculations. On InP(110),
due to the high spectral resolution of Raman spectroscopy, several surface modes predicted by theory can be experimentally
verified. Surface electronic transitions are detected by changing the energy of the exciting laser light indicating resonances
in the RS cross section.
Received: 7 April 1999 / Accepted: 25 June 1999 / Published online: 16 September 1999 相似文献
12.
D. Ning Q. H. Lou J. X. Dong Y. R. Wei 《Applied Physics A: Materials Science & Processing》1996,62(6):509-512
After being irradiated in air by a XeCI (308 nm) excimer laser, the electrical conductivity of solid thin-film C60 has been improved by more than six orders of magnitudes. The products resulting from laser irradiation of C60 films have been investigated by Raman scattering and the onset of conductivity can be attributed to laser-induced oxygenation and disintegration of the fullerene. Irradiated by 40 ns laser pulses with different fluence, products with different microstructure were observed. At lower fluence, the Raman features of microcrystalline graphite and fullerene polymer were observed. At a fluence just below the ablation threshold (36 mJ/cm2), the fullerene molecules in the film were disintegrated completely and transformed to amorphous graphite. 相似文献
13.
W. Ma M. Zhang T. Yu Y. Chen N. Ming 《Applied Physics A: Materials Science & Processing》1998,66(3):345-349
3 were successfully grown on Pt-coated SrTiO3 single-crystal substrates by metalorganic chemical vapor deposition (MOCVD) and were investigated by using X-ray diffraction
(XRD), scanning electron microscopy (SEM) and Raman spectroscopy. The as-deposited thin films were found to be highly (001)-oriented
with an average grain size of about 0.3 μm. Both a decrease of the tetragonality and a frequency downshift of the long-wavelength
optical phonons were observed and attributed to the effect of compressive stress in the thin films. However, Raman scattering
studies estimated a stress value of 2.6 GPa, which is much larger than the value of 0.75 GPa obtained from the XRD analyses.
Raman spectroscopic studies also confirmed the grain-size-related disorder feature in the as-grown PbTiO3 thin films. Structural investigations implied the weakening of ferroelectricity in the heteroepitaxial ferroelectric thin
films.
Received: 1 April 1997/Accepted: 14 July 1997 相似文献
14.
B. Todorovi? Markovi? V. Jokanovi? S. Jovanovi? D. Kleut M. Drami?anin Z. Markovi? 《Applied Surface Science》2009,255(17):7537-7541
In this study different encapsulating agents have been used for chemical modification of fullerenes. Fullerenes have reacted with tetrahydrofuran, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate and ethylene vinyl acetate-ethylene vinyl versatate at room temperature under mechanical milling. The obtained powder has been dispersed in water by ultrasonication. The fullerene based colloids have been characterized by UV-vis, FTIR, Raman spectroscopy and atomic force microscopy. FTIR and Raman analysis have shown the presence of C60 after surface functionalization. 相似文献
15.
M. Afzelius P.-E. Bengtsson J. Bood J. Bonamy F. Chaussard H. Berger T. Dreier 《Applied physics. B, Lasers and optics》2002,75(6-7):771-778
Rotational coherent anti-Stokes Raman spectroscopy (CARS) is a well-established spectroscopic technique for thermometry at
pre-combustion temperatures and atmospheric pressure. However, at pressures of several MPa, a previous investigation revealed
large discrepancies between experimental data and the theoretical model. A re-evaluation has been made of these data (at room
temperature and in the range 1.5–9 MPa) with two improvements to the spectral code. The first is the inclusion of an inter-branch
interference effect, which is described in detail in Paper I. The second is the use of experimental S1-branch Raman line widths measured at 295 K, with a temperature dependence extracted from semi-classical calculations following
the Robert–Bonamy formalism. It is shown that these two modifications significantly improve the theoretical model, since both
the spectral fits and the accuracy of the evaluated temperatures are considerably improved.
Received: 18 February 2002 / Revised version: 9 July 2002 / Published online: 22 November 2002
RID="*"
ID="*"Corresponding author. Fax: +46-46/2224542, E-mail: mikael.afzelius@forbrf.lth.se 相似文献
16.
Brillouin scattering from thermally excited magnons and ferromagnetic resonance are used to determine the spin wave dispersion
of the low-frequency spin wave branch in FeBO3, a transparent weak ferromagnet. In addition to the dominant exchange and Zeeman contributions, the investigation takes into
account magnetic dipole and magnetoelastic interactions. Due to the antisymmetric exchange enhancement the material exhibits
a broad spin wave band and a large gap energy at small magnetic fields. Competing directional dependences of the dipole and
the exchange energy produce a degeneracy of spin waves with a certain magnitude of the wavevector propagating in different
directions. The gap energy is shown to be due to magnetoelastic coupling, whereas the contribution of the anisotropy in the
easy plane is negligible atT=300 K. 相似文献
17.
Modification of the fused silica glass network associated with waveguide fabrication using femtosecond laser pulses 总被引:1,自引:0,他引:1
J.W. Chan T.R. Huser S.H. Risbud D.M. Krol 《Applied Physics A: Materials Science & Processing》2003,76(3):367-372
Atomic-scale structural changes have been observed in the glass network of fused silica after modification by tightly focused
800-nm, 130-fs laser pulses at fluences between 5 and 200 J cm-2. Raman spectroscopy of the modified glass shows an increase in the 490 and 605-cm-1 peaks, indicating an increase in the number of 4- and 3-membered ring structures in the silica network. These results provide
evidence that densification of the glass occurs after exposure to fs pulses. Fluorescence spectroscopy of the modified glass
shows a broad fluorescence band at 630 nm, indicating the formation of non-bridging oxygen hole centers (NBOHC) by fs pulses.
Waveguides that support the fundamental mode at 633 nm have been fabricated inside fused silica by scanning the glass along
the fs laser beam axis. The index changes are estimated to be approximately 0.07×10-3.
Received: 17 December 2001 / Accepted: 9 July 2002 / Published online: 25 October 2002
RID="*"
ID="*"Corresponding author. Fax: +1-925/423-2463, E-mail: dmkrol@ucdavis.edu 相似文献
18.
19.
We present Raman scattering on carbon nanotubes functionalized with pentyl groups. Studies of the intermediate frequency region and the C–H bond stretching signal along with the D mode show evidence of the addition reaction by Raman spectroscopy. From the resonance profiles of the radial breathing mode (RBM) we assign the chiral indices of the tubes and study the influence of the functionalization on the transition energies, shift and intensity of the RBM signal. The largest effect we observe is on the Raman intensity of the radial breathing mode. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
20.
Q. Ren D. Xu Y.T. Chow Z.H. Lü C.B. Ma G.H. Zhang H.P. Chan P.L. Chu 《Applied Physics A: Materials Science & Processing》2003,76(2):183-186
Composite thin films of PbTiO3 nanocrystals and high-transparency PEKc polymer for applications in electro-optical devices were prepared using the spin
coating technique. The size of the PbTiO3 nanocrystals was estimated to be 30–40 nm using a transmission electron microscope. The transmission technique, a simple
method for measuring the electro-optic coefficients of poled composite polymer films was developed. The electro-optic coefficient
γ33 of poled PbTiO3/PEKc composite polymer films was measured to be 18.34 pm V-1 at 633 nm under room temperature. The index at 633 nm and the dielectric constant at 100 kHz under room temperature were
determined to be 1.65248 and 7.32, respectively. The figure of merit F2=n7γ2/ε was estimated to be 1546, showing very good electro-optical properties.
Received: 5 February 2002 / Accepted: 12 March 2002 / Published online: 19 July 2002
RID="*"
ID="*"Corresponding author. Fax: +852/2788-7791, E-mail: eeytc@cityu.edu.hk 相似文献