共查询到20条相似文献,搜索用时 15 毫秒
1.
Growth and characterization of silicon nitride films on various underlying materials 总被引:3,自引:0,他引:3
G.C. Han P. Luo K.B. Li Z.Y. Liu Y.H. Wu 《Applied Physics A: Materials Science & Processing》2002,74(2):243-247
Characteristics of silicon nitride (SiNx:H) films, grown by plasma enhanced chemical vapor deposition (PECVD) on various metals such as Ta, IrMn, NiFe, Cu, and CoFe
at various temperatures down to 100 °C, were studied using measurements of BHF etch rate, surface roughness and Auger electron
spectroscopy (AES). The results were compared with those obtained for SiNx:H films on Si. The deposition rate of SiNx:H films increased slightly as deposition temperature decreased, and showed a weak dependence on the underlying materials.
The surface of the nitride films deposited on all underlying materials at lower temperatures (below 150 °C) became rougher.
In particular, a bubble-like surface was observed on the nitride film deposited on NiFe at 100 °C. At higher deposition temperatures
(above 200 °C), SiNx:H films on all the above metals had small RMS values, except for films on Cu which cracked at 250 °C. BHF (10:1) etch rate
increased dramatically for nitride films deposited below 150 °C. For different underlying films, the BHF etch rate was quite
different, but exhibited the same trend with decrease in deposition temperature. AES measurements showed that Si and N concentrations
in the SiNx:H films were only slightly different for the various deposition temperatures and underlying materials. AES depth profile
of nitride films indicated that both surface O content and the depth of oxygen penetrating into SiNx:H increased for low temperature-deposited films. However, there was no observed oxygen signal from within the films, even
for films deposited at 100 °C, and both Si and N concentrations were uniform throughout the film.
Received: 26 October 2001 / Accepted: 2 March 2001 / Published online: 20 June 2001 相似文献
2.
A. Thomasson S. Geffroy E. Frejafon D. Weidauer R. Fabian Y. Godet M. Nominé T. Ménard P. Rairoux D. Moeller J.P. Wolf 《Applied physics. B, Lasers and optics》2002,74(4-5):453-459
Continuous mapping of an ozone episode in Paris in June 1999 has been performed using a differential absorption lidar system.
The 2D ozone concentration vertical maps recorded over 33 h at the Champ de Mars are compiled in a video clip that gives access
to local photochemical dynamics with unprecedented precision. The lidar data are compared over the whole period with point
monitors located at 0-, 50-, and 300-m altitudes on the Eiffel Tower. Very good agreement is found when spatial resolution,
acquisition time, and required concentration accuracy are optimized. Sensitivity to these parameters for successful intercomparison
in urban areas is discussed.
Received: 11 February 2002 / Published online: 14 March 2002 相似文献
3.
J.P. Zhao Z.Y. Chen T. Yano T. Ooie M. Yoneda J. Sakakibara 《Applied Physics A: Materials Science & Processing》2001,73(1):97-101
Carbon nitride films with high nitrogen content were prepared by reactive pulsed-laser deposition at nitrogen partial pressures
varying from 0.1 to 20.0 Torr. It was found that the nitrogen content in the films first increases with increase of the nitrogen
pressure, reaches a maximum of 46 at. % at 5.0 Torr, and then decreases to 37 at. % at 20.0 Torr. The almost pure carbon nitride
films were systematically characterized by using X-ray photoelectron spectroscopy (XPS) concerning the core-level and valence-band
structures. Some fingerprint information, which shows the role of nitrogen in controlling the electronic structure of carbon
nitride films, was found based on the XPS studies. With enhancing the nitrogen incorporation, both the binding energy and
the peak intensity of the core-level and the valence-band spectra vary systematically as a function of nitrogen content in
the films.
Received: 26 June 2000 / Accepted: 26 June 2000 / Published online: 20 September 2000 相似文献
4.
S.F. Hanna R. Barron-Jimenez T.N. Anderson R.P. Lucht J.A. Caton T. Walther 《Applied physics. B, Lasers and optics》2002,75(1):113-117
An all-solid-state continuous-wave laser system for ultraviolet absorption measurements of the nitric oxide (NO) molecule
has been developed and demonstrated. The single-mode, tunable output of a 10-mW, 395-nm external-cavity diode laser (ECDL)
is sum-frequency-mixed with the output of a 115-mW, frequency-doubled, diode-pumped Nd:YAG laser in a beta-barium-borate crystal
to produce 40 nW of tunable radiation at 226.8 nm. The wavelength of the 395-nm ECDL is then scanned over NO absorption lines
to produce fully resolved absorption spectra. Initial results from mixtures of NO in nitrogen in a room-temperature gas cell
are discussed. The estimated NO detection limit of the system for a demonstrated absorption sensitivity of 2×10-3 is 0.2 ppm per meter of path length for 300 K gas. The estimated accuracy of the measurements is ±10%.
Received: 25 February 2002 / Revised version: 31 May 2002 / Published online: 8 August 2002 相似文献
5.
Differentiation and subtraction of amplitude and phase images using a photorefractive novelty filter
M. Sedlatschek J. Trumpfheller J. Hartmann M. Müller C. Denz T. Tschudi 《Applied physics. B, Lasers and optics》1999,68(5):1047-1054
In this article, we demonstrate the capability of a two-beam coupling photorefractive optical novelty filter of detecting
changes in the amplitude or phase of optical images. These changes may either be continuous or discrete in time. The performance
of the two-beam coupling novelty filter is investigated and expressions for the output contrast corresponding to phase and
amplitude changes based on a novel, simple interference model of two-beam coupling are derived. These expressions are verified
by experimental results on the novelty contrast, revealing that the amplitude contrast is not described correctly by the commonly
accepted coupled-wave theory. The novelty filter was applied to the detection of temporally continuous phase changes provided
by a gas flow and moving microscopic objects. A novel scheme for image subtraction is also demonstrated, showing the novelty
filter’s ability to detect temporally discrete changes.
Received: 14 November 1998 / Revised version: 18 January 1999 / Published online: 12 April 1999 相似文献
6.
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
7.
Fengting Lü 《Applied Surface Science》2007,253(9):4123-4131
A novel fluorescence film has been fabricated by covalently coupling anthracene on a glass plate surface via a long flexible “Y” type spacer. Fluorescence measurement demonstrated that the emission of the film is dominated by anthracene monomer emission, and the emission can be selectively quenched by organic copper(II) salts including copper acetate, copper citrate, copper tartrate, etc. Addition of inorganic copper(II) salts like Cu(NO3)2, CuSO4, CuCl2, etc., however, has little effect upon the emission of the film. This observation was explained by considering the screening effect of the spacer layer, or spacer clusters, or even spacers adopting compact coiled conformation. Different from the reported fluorescence films with similar structures, immobilization of anthracene via a “Y” type spacer on a glass plate surface makes the fluorophore moieties exist in two different states, that is some of them were embedded within the spacer structures, and some of them might stay out of the structures. This hypothesis has been confirmed by model system, solvent effect and quenching mechanism studies. The emission of the film is sensitive to the presence of organic copper(II) salts like copper acetate. The response of the film to copper acetate is fully reversible. Presence of other inorganic salts, including Pb(Ac)2, Cd(Ac)2, Zn(Ac)2, and inorganic copper(II) salts has little effect upon the sensing performance of the film to copper acetate. 相似文献
8.
Parameters of eyesafe lidar at 1.54 μm for detection of small plumes of smoke from burning wood or oil have been evaluated.
It was assumed that a diode-pumped solid-state Er:glass laser at 1.54 μm or a Nd:YAG laser with a Raman cell or optical-parametric
oscillator is used as a light source and that detection of backscattered light is performed with an avalanche photodiode.
Ash and soot particle size distributions were taken from experiments. A backscattering coefficient at 1.54 μm for various
source of smoke was estimated. In computing the laser energy, range between lidar and smoke, receiver optics diameter, fuel
mass burned in unit time, fire source radius, laser pulse duration and visibility were varied. Results of the computations
enabled estimation of the required laser energy, which ranges from 0.05 to 1400 mJ depending on the parameters.
Received: 5 January 2000 / Revised version: 3 March 2000 / Published online: 11 May 2000 相似文献
9.
F. Immler 《Applied physics. B, Lasers and optics》2003,76(5):593-596
Aerosols can introduce significant errors in measurements of trace gas concentration profiles with differential absorption
lidar (DIAL). Here, a solution to counteract the aerosol effect is introduced, which does not depend on additional measurements
and is applicable when absorption at the off-wavelength is not negligible. It is based on a numerical solution of the coupled
lidar equations and calculates the trace-gas concentration and the aerosol backscatter ratio simultaneously. Consequently,
most of the errors introduced by aerosols to DIAL measurements are inherently corrected and, additionally, the aerosol backscatter
profiles at the DIAL wavelengths are obtained.
Received: 23 December 2002 / Revised version: 24 March 2003 / Published online: 14 May 2003
RID="*"
ID="*"Corresponding author. Fax: +49-331/288-2178, E-mail: fimmler@awi-bremerhaven.de Present address: AWI Bremerhaven, Am
Handelshafen 12, 27570 Bremerhaven, Germany 相似文献
10.
Synthesis of carbon nitride films by low-power inductively coupled plasma-activated transport reactions from a solid carbon source 总被引:1,自引:0,他引:1
C. Popov M.F. Plass A. Bergmaier W. Kulisch 《Applied Physics A: Materials Science & Processing》1999,69(2):241-244
Thin films of carbon nitride were prepared by low-power inductively coupled plasma chemical vapor deposition from a solid
carbon source by utilizing transport reactions. The maximum deposition rate achieved was 10 nm/min and depended mainly on
the substrate position in the reactor. The nitrogen fraction in the films was not so sensitive to the process parameters and
was at about 0.5 for all experiments as measured by Auger electron spectroscopy (AES) and elastic recoil detection (ERD) analysis.
The chemical bonding structure studied by Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy
(XPS) showed the presence of triple, double and single bonds between carbon and nitrogen atoms.
Received: 12 May 1999 / Accepted: 12 May 1999 / Published online: 24 June 1999 相似文献
11.
The efficiencies of direct lidars operating at 355, 532, 1064 and 1540-nm radiation wavelengths for early forest fire detection
were compared. For each wavelength, the range for reliable smoke-plume detection was estimated on the basis of a computer
simulation plume using a one-dimensional “top-hat” gas dynamic model for the calculation of the backscattering and extinction-coefficient
profiles within the plume. The agreement between the predicted signal-to-noise ratio (SNR) and experimental results for 532
and 1064-nm wavelength radiation is good. The decrease of the signal-to-noise ratio with distance is maximum for 355 nm and
minimum for 1064 nm. At 1540 nm, the decay of SNR with distance is slightly faster, but the SNR is higher than for other wavelengths,
leading to the highest detection efficiency for the same energy of the probing laser pulse. For a burning rate of 2 kg/s and
a laser beam divergence of 2.5 mr, the maximum distance for reliable detection varies between 6 and 12 km, depending on the
wavelength.
Received: 15 May 2002 / Revised version: 13 September 2002 / Published online: 22 January 2003
RID="*"
ID="*"Corresponding author. Fax: +351-21/841-8120, E-mail: rui.vilar@ist.utl.pt 相似文献
12.
A.B. Utkin A.V. Lavrov L. Costa F. Simões R. Vilar 《Applied physics. B, Lasers and optics》2002,74(1):77-83
The possibility of detecting small forest fires with the help of a simple and cheap lidar operating at 0.532-μm wavelength
up to distances of about 6.5 km is demonstrated. The values of the signal-to-noise ratio (SNR) achieved in the experiments
are consistent with theoretical estimations obtained by computational modeling of the lidar detection process, including simulation
of the smoke-plume shape and of the laser beam–plume interaction. This model was used to assess the potential of the lidar
technique for fire surveillance in large forest areas. In particular, the upper limiting range for effective detection (SNR>5)
of small localized fires in dry- and clear-weather conditions is estimated at 7–15 km depending on operation mode, burning
rate, and observation geometry.
Received: 29 August 2001 / Published online: 29 November 2001 相似文献
13.
J. Wang S.T. Sanders J.B. Jeffries R.K. Hanson 《Applied physics. B, Lasers and optics》2001,72(7):865-872
Measurements of oxygen concentration at high pressures (to 10.9 bar) were made using diode-laser absorption of oxygen A-band
transitions near 760 nm. The wide current-tuning frequency range (>30 cm-1) of vertical cavity surface-emitting lasers (VCSELs) was exploited to enable the first scanned-wavelength demonstration of
diode-laser absorption at high pressures; this strategy is more robust than fixed-wavelength strategies, particularly in hostile
environments. The wide tuning range and rapid frequency response of the current tuning were further exploited to demonstrate
wavelength-modulation absorption spectroscopy in a high-pressure environment. The minimum detectable absorbance demonstrated,
∼1×10-4, corresponds to ∼800 ppm-m oxygen detectivity at room temperature and is limited by etalon noise. The rapid- and wide-frequency
tunability of VCSELs should significantly expand the application domain of absorption-based sensors limited in the past by
the small current-tuning frequency range (typically <2 cm-1) of conventional edge-emitting diode lasers.
Received: 26 July 2000 / Revised version: 2 January 2001 / Published online: 20 April 2001 相似文献
14.
Z.Y. Chen J.P. Zhao T. Yano T. Ooie 《Applied Physics A: Materials Science & Processing》2002,75(2):213-216
Raman characteristics of carbon nitride films synthesized by nitrogen-ion-beam-assisted pulsed laser deposition were investigated.
In addition to the D (disorder) band and G (graphitic) band commonly observed in carbon nitride films, two Raman bands located
at 1080–1100 and 1465–1480 cm-1 were found from our carbon nitride films. These two bands were well matched with the predicted Raman frequencies for βC3N4 and the observed Raman bands reported for carbon nitride films, indicating their relation to carbon-nitrogen stretching vibrations.
Furthermore, the relative intensity ratio of the two Raman bands to the D and G bands increased linearly with increasing nitrogen
content of the carbon nitride films.
Received: 30 October 2000 / Accepted: 5 February 2001 / Published online: 2 October 2001 相似文献
15.
Modeling of UV pulsed-laser ablation of metallic targets 总被引:1,自引:0,他引:1
S. Amoruso 《Applied Physics A: Materials Science & Processing》1999,69(3):323-332
A model to describe the laser ablation of metallic targets is presented. It accounts for the main physical processes involved
in the laser–solid–plasma interaction by considering the photon absorption and the ionization mechanisms that are active in
the plasma, as well as the laser-produced plasma kinetics. The model is used to simulate the laser ablation of aluminum targets
irradiated with a 6-ns UV laser pulse at 0.35 μm, and the results are compared with experimental findings. Calculations show
that all the investigated plasma parameters strongly depend on the laser intensity until a roll-off is reached at irradiance
≥1.5 GW cm-2. The satisfactorily good agreement between model predictions and experimental findings confirms that laser–plasma interaction
processes and plasma kinetics play a relevant role during nanosecond laser ablation of metals in the laser intensity range
of concern in this study.
Received: 12 February 1999 / Accepted: 12 April 1999 / Published online: 7 July 1999 相似文献
16.
Z.-M. Ren P.-N. Wang Y.-C. Du Z.-F. Ying F.-M. Li 《Applied Physics A: Materials Science & Processing》1997,65(4-5):407-409
2 radicals when the 355 and 1064 nm outputs of a Nd:YAG laser were applied. While for the 532 nm ablation, a relatively higher
concentration of excited atomic carbon was obtained. Different Raman and FTIR spectral features were observed from the deposited
films with different ablation wavelengths. The 532 nm laser ablation is proposed for the synthesis of high quality carbon
nitride films.
Received: 16 October 1996 / Accepted: 11 April 1997 相似文献
17.
Spectroscopic sensing of gases can be performed with high sensitivity and photometric precision by cavity ringdown (CRD) absorption
spectroscopy. Our cavity ringdown spectrometer incorporates continuous-wave (cw) tunable diode lasers, fibre-optic coupling
and standard photonics and optical telecommunications components. It comprises a rapidly swept optical cavity in a single-ended
optical heterodyne transmitter–receiver configuration, enabling optical absorption of gases to be recorded either as single-frequency
scanned spectra or as simultaneous, multi-wavelength tailored spectra. By measuring weak near-infrared rovibrational spectra
of carbon dioxide gas (CO2), with high resolution in the vicinity of 1.53 μm, we have realised a noise-limited absorption sensitivity of 2.5×10-9 cm-1 Hz-1/2. Analytical sensitivity limits (both actual and projected) and prospective gas-diagnostic applications are discussed. Our
approach to cw-CRD spectroscopy offers high performance in a relatively simple, low-cost, compact instrument that is amenable
to chemical analysis of trace gases in medical, agricultural, industrial and environmental situations.
Received: 16 May 2002 / Revised version: 3 June 2002 / Published online: 21 August 2002
RID="*"
ID="*"Corresponding author. Fax: +61-2/9850-8313, E-mail: brian.orr@mq.edu.au 相似文献
18.
Weili Zhang Yiben XiaJianhua Ju Linjun WangZhijun Fang Minglong Zhang 《Solid State Communications》2003,126(3):163-166
The electrical conductivity of nitride carbon (DLC: N) films has been studied. It is found that the electrical conductivity of the deposited films increases slowly with increasing nitrogen content, however, it decreases after the nitrogen content in the film reaches a certain value of 12.8 at%. Thermal treatment results show that the electrical conductivity of the lowly nitrogen doped DLC film increases rapidly, while that of the heavily doped film decreases after annealing at 300 °C for 30 min. Raman and XPS spectra results show that when the nitrogen content in the films reaches a certain value, there appears nonconductive phases. Therefore the electrical conductivity of the heavily doped films decreases. FTIR spectra analysis results show that the nitrogen atom as an impurity center undergoes an ‘activation’ process during the thermal treatment, which leads to the increase of the electrical conductivity. Therefore, the nitrogen in these two kinds of films has different effects on the electrical conductivity. 相似文献
19.
The gas-sensing potential of nanocrystalline SnO2 produced by a mechanochemical milling via centrifugal action 总被引:1,自引:0,他引:1
Ü. Kersen 《Applied Physics A: Materials Science & Processing》2002,75(5):559-563
In this work, the synthesis of undoped nanocrystalline tin dioxide powders and the subsequent preparation of SnO2 thick-films were studied. An initial mixture of SnCl2 and Ca(OH)2 was sealed in a vial for milling in an air atmosphere. Heat treatment of the milled powder resulted in the formation of tetragonal
and orthorhombic SnO2 phases, which was confirmed by X-ray diffraction (XRD) analysis. It was found that crystallite size could be controlled by
varying the milling time, the rotation speed and the temperature used for the heat treatment. Crystallite sizes in the range
20 to 30 nm (determined by XRD measurements) were obtained. The total pore volume was 0.22 ml/g for a measured particle size
of 37 m2/g. No contamination of the powder during milling was found. The response of the prepared thick-films to H2S gas in the concentration range 0.5 to 10 ppm in air was investigated as a function of the preparation conditions. The advantage
of mechanochemical synthesis of powder is its relative simplicity, low cost and possibility of obtaining isolated, unagglomerated
nanosized grains. It is shown that chemical reactions, which usually occur in the vibratory mill to produce the SnO phase,
can also be initiated during a short processing time in the centrifugal mill.
Received: 25 July 2001 / Accepted: 4 September 2001 / Published online: 20 December 2001 相似文献
20.
The technology and applications of the differential absorption lidar (DIAL) technique have progressed significantly since
the first DIAL measurements of Schotland [1], and airborne DIAL measurements of ozone and water vapor are frequently being
made in a wide range of field experiments. In addition, plans are underway to develop DIAL systems for use on satellites for
continuous global measurements. This paper will highlight the history of airborne lidar and DIAL systems, summarize the major
accomplishments of the NASA Langley DIAL program, and discuss specifications and goals for DIAL systems in space.
Received: 2 April 1998 相似文献