共查询到20条相似文献,搜索用时 46 毫秒
1.
Chan y Díaz E. Duarte-Moller A. Camacho Juan M. Castro-Rodríguez R. 《Applied Physics A: Materials Science & Processing》2012,106(3):619-624
SnO2 thin films have been deposited on glass substrates by pulsed Nd:YAG laser at different oxygen pressures, and the effects
of oxygen pressure on the physical properties of SnO2 films have been investigated. The films were deposited at substrate temperature of 500°C in oxygen partial pressure between
5.0 and 125 mTorr. The thin films deposited between 5.0 to 50 mTorr showed evidence of diffraction peaks, but increasing the
oxygen pressure up to 100 mTorr, three diffraction peaks (110), (101) and (211) were observed containing the SnO2 tetragonal structure. The electrical resistivity was very sensitive to the oxygen pressure. At 100 mTorr the films showed
electrical resistivity of 4×10−2 Ω cm, free carrier density of 1.03×1019 cm−3, mobility of 10.26 cm2 V−1 s−1 with average visible transmittance of ∼87%, and optical band gap of 3.6 eV. 相似文献
2.
M. Shahid Rafique Shazia Bashir Ali Ajami Wolfgang Husinsky Alison Hobro Bernhard Lendl 《Applied Physics A: Materials Science & Processing》2010,101(3):551-554
Investigations have been performed to explore ultrashort laser irradiation effects on the surface topography as well as structural
and nonlinear absorption properties of a polymer CR-39. For this purpose, a CR-39 target was exposed in air to 25 fs, 800 nm
Ti:sapphire laser radiation at fluences ranging from 0.25 J cm−2 to 3.6 J cm−2. The surface features, structural changes and nonlinear absorption were explored by AFM, Raman Spectroscopy and a Z-scan
technique, respectively. Several topographical structures like bumps, explosions and nano cavities have been observed on the
irradiated surface. Raman spectroscopy reveals changes in the fundamental structure of the polymer after the irradiation.
Nonlinear absorption data contained by the Z-scan technique predict the dominance of three-photon absorption in case of pristine
CR-39. Furthermore, nonlinear absorption (three or two photon) increases with increasing laser fluences and is well correlated
with surface and structural changes revealed by AFM and Raman spectroscopy. 相似文献
3.
M. Jelinek J. Lančok M. Pavelka P.A. Atanasov A. Macková F. Flory C. Garapon 《Applied Physics A: Materials Science & Processing》2002,74(4):481-485
Nd: KGd(WO4)2 thin films were deposited by KrF laser ablation on MgO, YAP, YAG and Si substrates at temperatures up to 800 °C. Film crystallinity,
morphology, stoichiometry (WDX, RBS and PIXE), excitation spectra, fluorescence, refractive index and waveguiding properties
were studied in connection with deposition conditions. The best films were crystalline and exhibited losses of approximately
5 dB cm-1 at a wavelength of 633 nm.
Received: 8 January 2001 / Accepted: 7 November 2001 / Published online: 11 February 2002 相似文献
4.
Laser crystals Nd3+:Gd3Ga5O12 (Nd:GGG) and Nd3+:Gd3Sc2Ga3O12 (Nd:GSGG) were grown by Czochralski method. The influence of gamma-ray irradiation on their absorption and luminescence spectra has been investigated. Two additional absorption (AA) bands induced by gamma-ray irradiation appear in the spectra of Nd:GGG crystal while only a very weak AA band appears for the Nd:GSGG crystal. This indicated that Nd:GSGG crystal has stronger ability to resist the color center formation by irradiation. The intensity of the excitation and emission spectra of Nd:GGG crystal decrease after the irradiation of 100 Mrad gamma-ray. In contrast, a luminescence strengthening effect was observed in Nd:GSGG crystal after exposure to the same irradiation dose. The results showed that the Nd:GSGG crystal is a promising candidate used under radiation environments such as in outer space. 相似文献
5.
We study the dynamics of ions produced upon ablation of Al and ceramic Al2O3 targets using nanosecond laser pulses at 193 nm (6.4 eV) as a function of the laser fluence from threshold up to 12 J cm−2. An electrical (Langmuir) probe located at 40 mm from the target surface has been used for determining the ion yield and
calculating the kinetic energy distributions. The results for both targets show the existence of a significant amount of ions
having kinetic energies >200 eV (≈20% around threshold fluence), and kinetic energies are up to >1.5 keV. The results are
related with the existence of direct photonionization processes caused by the photon energy of the laser being higher than
the ionization potential of Al (5.98 eV). Comparison of the ion yield when ablating the two types of targets for fluences
above threshold to data reported in the literature suggests that the magnitude of the yield and its threshold are parameters
depending on the thermal properties of the target rather than on the laser wavelength. Around threshold, the different behavior
of ion yield when ablating Al and Al2O3 targets suggests that the threshold for neutral aluminium and ion species in the case of ablation of the Al2O3 target must be similar. 相似文献
6.
Enrique Camps L. Escobar-Alarcón V. H. Castrejón-Sánchez P. Tolentino-Eslava 《Applied Physics A: Materials Science & Processing》2008,93(3):759-763
Amorphous carbon thin films were deposited by laser ablation of a graphite target, using the fundamental line of a 5 ns Nd:YAG
laser. Deposition was carried out as a function of the plasma parameters (mean kinetic ion energy and plasma density), determined
by means of a planar probe. In the selected working regimes the optical emission from the plasma is mainly due to atomic species,
namely C+ (426.5 nm); however, there is also emission from other atomic species and molecular carbon. The hardness and resistivity
could be varied in the range between 10 and 25 GPa, and 108 and 1011 Ω cm, respectively. The maximum values were obtained at a 200 eV ion energy and 6×1013 cm−3 plasma density, where the maximum quantity of C–C sp3 bonds was formed, as confirmed by Raman spectroscopy. 相似文献
7.
E. Coetsee J. J. Terblans H. C. Swart 《Applied Physics A: Materials Science & Processing》2010,101(4):645-650
Y2SiO5:Ce phosphor thin films were grown onto Si(100) substrates with pulsed laser deposition (PLD) using a 248-nm KrF excimer laser.
Process parameters were varied during the growth process and the effect on the surface morphology and cathodoluminescence
(CL) was analysed. The process parameters that were changed included the following: gas pressure (vacuum (5×10−6 Torr), 1×1−2 Torr and 1 Torr O2), different gas species (O2, Ar and N2 at a pressure of 455 mTorr), laser fluence (1.6±0.1 J cm−2 and 3.0±0.3 J cm−2) and substrate temperature (400 and 600°C). The surface morphology was investigated with atomic force microscopy (AFM). The
morphology of the thin films ablated in vacuum and 10 mTorr ambient O2 showed more or less the same trend. An increase in the pressure to 1 Torr O2, however, showed a definite increase in deposited particle sizes. Ablation in N2 gas resulted in small particles of 20 nm in diameter and ablation in O2 gas produced bigger particles of 20, 30 and 40 nm as well as an agglomeration of these particles into bigger size clusters
of 80 to 100 nm. Ablation in Ar gas led to particle sizes of 30 nm and the particles were much more spherically defined and
evenly distributed on the surface. The higher fluence deposition led to bigger particle and grain sizes as well as thicker
layers with respect to the lower fluence. The particle sizes of the higher fluence vary mainly between 130 and 140 nm and
the lower fluence sizes vary between 50 and 60 nm. The higher fluence particles consist of smaller particles ranging from
5 to 30 nm as measured with AFM. The surface structure of the thin film ablated at 400°C substrate temperature is less compact
(lesser agglomeration of particles than at 600°C). The increase in substrate temperature definitely resulted in a rougher
surface layer. CL was measured to investigate the effect of the surface morphology on the luminescent intensities. The increased
O2 ambient (1 Torr) resulted in a higher CL intensity compared to the thin films ablated in vacuum. The thin film ablated in
Ar gas showed a much higher CL intensity than the other thin films. Ablation at a high fluence resulted in a higher CL intensity.
The higher substrate temperature resulted in better CL intensities. The more spherically shaped particles and rougher surface
led to increase CL intensities. 相似文献
8.
E. D'Anna A. V. Drigo G. Leggieri A. Luches G. Majni P. Mengucci 《Applied Physics A: Materials Science & Processing》1990,50(4):411-415
Thin chromium films, 60 nm thick, were deposited onto single-crystal silicon wafers. The samples were irradiated with 30 ns single pulses from a Nd: glass laser at fluences ranging from 0.4 to 2.25 J/cm2. Rutherford backscattering spectrometry, transmission electron microscopy and electron diffraction measurements evidence the formation of CrSi2 layers at the Cr/Si interface. The silicide thickness depends on the laser fluence. 相似文献
9.
Yoshie Ishikawa Qi Feng Naoto Koshizaki 《Applied Physics A: Materials Science & Processing》2010,99(4):797-803
We studied the fabrication of B4C submicron particles by laser irradiation of boron nanoparticles dispersed in an organic solvent. The spherical shape of
the formed particles suggests that instantaneous melt formation and solidification by quenching are involved in the particle-forming
process. B4C particles gradually became larger with irradiation time at relatively low laser fluence (1.5 J cm−2 pulse−1) by repetitive melting and fusion of the particles, and the B4C yield increased with irradiation time to 90% for 600 min of irradiation. At higher laser fluences, the B4C yield decreased due to the explosive ablation of boron or B4C to form H3BO3, and thus only the larger B4C particles were observed. The dielectric constant of the organic solvent also affected the generated B4C particle size, probably due to the degree of particle aggregation. Thus, this technique can provide a new approach for fabricating
spherical submicron particles of ceramic materials, such as carbides, with simple and safe processes. 相似文献
10.
Radek Zeipl Jarmila Walachová Martin Pavelka Miroslav Jelínek Václav Studnička Tomáš Kocourek 《Applied Physics A: Materials Science & Processing》2008,93(3):663-667
Room temperature conductivity and the Seebeck coefficient of thin layers prepared by laser ablation from Bi2Te3 target were explored. The power factor was calculated for samples prepared at substrate temperature of 360°C with the density
of the laser beam 5 J cm−2 and at substrate temperature of 410°C with the density of the laser beam 2 J cm−2 during the deposition. Oscillations of the conductivity and the power factor with the layer thickness were observed at room
temperature. The oscillations of conductivity were also verified at the temperature of 77 K. The period of oscillations depends
on the preparation conditions. This behavior has been theoretically explained by the quantum size effect in the layers containing
different phases and in addition, it was demonstrated by the X-ray Diffraction measurement.
The behavior of the power factor of the layers is compared to the behavior of the figure of merit of the layers published
earlier. 相似文献
11.
M. Shahid Rafique Shazia Bashir Ali Ajami Wolfgang Husinsky 《Applied Physics A: Materials Science & Processing》2010,100(4):1183-1189
We have investigated femtosecond laser irradiation effects on the surface topography, structural changes and nonlinear absorption
properties of CR-39. For this purpose, a CR-39 target was exposed in air to 25 fs, 800 nm Ti: sapphire laser radiation at
fluences ranging from 0.25 J cm−2 to 3.6 J cm−2. The surface of irradiated CR-39 probed by an Atomic Force Microscope (AFM) exhibits the formation of several topographical
structures, like bumps, explosions and nano cavities. Raman spectroscopy is performed to explore chemical and structural modification
of the irradiated target. The spectroscopy reveals changes such as cross linking, bond breaking, formation of new bonds etc.
in the fundamental structure of the polymer after irradiation. In order to establish a correlation between morphological and
structural changes with the changes in the nonlinear absorption of the irradiated CR-39, a Z-scan technique was employed.
A comparison of experimentally obtained data from Z-scan measurements with our calculations predicts the dominance of three-photon
absorption in the case of pristine CR-39, whereas for irradiated targets concurrence of three- and two-photon absorption is
probable. Nonlinear absorption increases with increasing laser fluences and is well correlated by surface and structural changes
revealed by AFM and Raman spectroscopy. 相似文献
12.
H. Kim A. Cepler C. Cetina D. Knies M. S. Osofsky R. C. Y. Auyeung A. Piqué 《Applied Physics A: Materials Science & Processing》2008,93(3):593-598
Present p-type ZnO films tend to exhibit high resistivity and low carrier concentration, and they revert to their natural n-type state
within days after deposition. One approach to grow higher quality p-type ZnO is by codoping the ZnO during growth. This article describes recent results from the growth and characterization
of Zr–N codoped p-type ZnO thin films by pulsed laser deposition (PLD) on (0001) sapphire substrates. For this work, both N-doped and Zr–N
codoped p-type ZnO films were grown for comparison purposes at substrate temperatures ranging between 400 to 700 °C and N2O background pressures between 10−5 to 10−2 Torr. The carrier type and conduction were found to be very sensitive to substrate temperature and N2O deposition pressure. P-type conduction was observed for films grown at pressures between 10−3 to 10−2 Torr. The Zr–N codoped ZnO films grown at 550 °C in 1×10−3 Torr of N2O show p-type conduction behavior with a very low resistivity of 0.89 Ω-cm, a carrier concentration of 5.0×1018 cm−3, and a Hall mobility of 1.4 cm2 V−1 s−1. The structure, morphology and optical properties were also evaluated for both N-doped and Zr–N codoped ZnO films. 相似文献
13.
Wee Ong Siew Seong Shan Yap Cécile Ladam Øystein Dahl Turid Worren Reenaas Teck Yong Tou 《Applied Physics A: Materials Science & Processing》2011,104(3):877-881
Nanosecond-pulsed KrF (248 nm, 25 ns) and Nd:YAG (1064 nm, 532 nm, 355 nm, 5 ns) lasers were used to ablate a polycrystalline
Si target in a background pressure of <10−4 Pa. Si films were deposited on Si and GaAs substrates at room temperature. The surface morphology of the films was characterized
using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Round droplets from 20 nm to 5 μm were detected
on the deposited films. Raman Spectroscopy indicated that the micron-sized droplets were crystalline and the films were amorphous.
The dependence of the properties of the films on laser wavelengths and fluence is discussed. 相似文献
14.
S. Y. Huang S. Xu Q. J. Cheng J. D. Long K. Ostrikov 《Applied Physics A: Materials Science & Processing》2009,97(2):375-380
Aluminum-doped p-type polycrystalline silicon thin films have been synthesized on glass substrates using an aluminum target
in a reactive SiH4+Ar+H2 gas mixture at a low substrate temperature of 300 °C through inductively coupled plasma-assisted RF magnetron sputtering.
In this process, it is possible to simultaneously co-deposit Si–Al in one layer for crystallization of amorphous silicon,
in contrast to the conventional techniques where alternating metal and amorphous Si layers are deposited. The effect of aluminum
target power on the structural and electrical properties of polycrystalline Si films is analyzed by X-ray diffraction, Raman
spectroscopy, scanning electron microscopy and Hall-effect analysis. It is shown that at an aluminum target power of 100 W,
the polycrystalline Si film features a high crystalline fraction of 91%, a vertically aligned columnar structure, a sheet
resistance of 20.2 kΩ/□ and a hole concentration of 6.3×1018 cm−3. The underlying mechanism for achieving the semiconductor-quality polycrystalline silicon thin films at a low substrate temperature
of 300 °C is proposed. 相似文献
15.
Iron oxide films were deposited on <100> Si substrates by reactive pulsed laser deposition (RPLD) using a KrF laser (248 nm).
These films were deposited too by laser (light) chemical vapor deposition (LCVD) using continuous ultraviolet photodiode radiation
(360 nm). The deposited films demonstrated semiconducting properties. These films had large thermo-electromotive force (e.m.f.)
coefficient (S) and high photosensitivity (F). For films deposited by RPLD the S coefficient varied in the range 0.8–1.65 mV/K at 205–322 K. This coefficient depended on the band gap (E
g
) of the semiconductor films, which varied in the range 0.43–0.93 eV. The largest F value found was 44 Vc/W for white light at power density I≅0.006 W/cm2. Using LCVD, iron oxide films were deposited from iron carbonyl vapor. For these films, the S coefficient varied in the range −0.5 to 1.5 mV/K at 110–330 K. The S coefficient depended on E
g
of the semiconductor films, which varied in the range 0.44–0.51 eV. The largest F value of these films was about 40 Vc/W at the same I≅0.006 W/cm2. Our results showed that RPLD and LCVD can be used to synthesize iron oxide thin films with variable stoichiometry and, consequently,
with different values of E
g
. These films have large S coefficient and high photosensitivity F and therefore can be used as multi-parameter sensors: thermo–photo sensors. 相似文献
16.
The specific heat of undercooled liquid Ni80Fe10Cu10 alloy was experimentally measured by electromagnetic levitation drop calorimeter, and also numerically simulated by the molecular
dynamics method. The achieved maximum undercooling is up to 252 K (0.15 T
L) in the experiments, and the measured result is 41.67 J mol−1 K−1. The simulation provides calculated data within 0∼702 K undercooling range, which is much broader than the experimental regime.
The simulated value is 37.02 J mol−1 K−1. Although there exists a difference of 4.65 J mol−1 K−1 between them, the result is quite acceptable for simulation. Furthermore, the liquid structure of undercooled Ni80Fe10Cu10 alloy is studied in terms of the total and partial pair distribution functions, which display that the ordered degree of
atoms enhances from a normal liquid to metastable state. 相似文献
17.
Thin films of molybdenum trioxide were deposited on glass substrates employing direct current (DC) magnetron sputtering by
sputtering of molybdenum at different oxygen partial pressures in the range 8 × 10−5–1 × 10−3 mbar and at a substrate temperature of 473 K. The glow discharge characteristics of magnetron cathode target of molybdenum
were studied. The influence of oxygen partial pressure on the structural and optical properties of molybdenum trioxide films
was investigated. The films formed at an optimum oxygen partial pressure of 2 × 10−4 mbar were polycrystalline in nature with orthorhombic α- phase and an optical band gap of 3.16 eV. The refractive index of
the films formed at an oxygen partial pressure of 2 × 10−4 mbar decreased from 2.08 to 1.89 with increase of wavelength from 450 to 1,000 nm, respectively.
Paper presented at the Third International Conference on Ionic Devices (ICID 2006), Chennai, Tamilnadu, India, Dec. 7–9, 2006. 相似文献
18.
SrBi2Ta2O9 (SBT) ferroelectric thin films with different preferred orientations were deposited by pulsed laser deposition (PLD). Several
methods have been developed to control the preferred orientation of SBT thin films. For SBT films deposited directly on Pt/TiO2/SiO2/Si substrates and in situ crystallized at the deposition temperature, the substrate temperature has a significant impact
on the orientation and the remnant polarization (Pr) of the films; a higher substrate temperature benefits the formation of
(115) texture and larger grain size. The films deposited on Pt/TiO2/SiO2/Si substrates at 830 °C are (115)-oriented and exhibit 2Pr of 6 μC/cm2. (115)- and (200)-predominant films can be formed by using a La0.85Sr0.15CoO3 (LSCO) buffer layer or by annealing amorphous SBT films deposited on Pt/TiO2/SiO2/Si substrates at 450 °C using rapid thermal annealing (RTA). These films exhibit good electric properties; 2Pr of the films
are up to 12 μC/cm2 and 17 μC/cm2, respectively. The much larger 2Pr of the films deposited on the LSCO buffer layer and of the films obtained by RTA than
2Pr of the films deposited on Pt/TiO2/SiO2/Si substrates at 830 °C is attributed to a stronger (200) texture.
Received: 30 January 2001 / Accepted: 30 May 2001 / Published online: 25 July 2001 相似文献
19.
Y. Isshiki J. Shi H. Nakai M. Hashimoto 《Applied Physics A: Materials Science & Processing》2000,70(4):395-402
Laser surface alloying (LSA) with silicon was conducted on austenitic stainless steel 304. Silicon slurry composed of silicon
particle of 5 μm in average diameter was made and a uniform layer was supplied on the substrate stainless steel. The surface
was melted with beam-oscillated carbon dioxide laser and then LSA layers of 0.4–1.2 mm in thickness were obtained. When an
impinged energy density was adjusted to be equal to or lower than 100 W mm−2, LSA layers retained rapidly solidified microstructure with dispersed cracks. In these samples, Fe3Si was detected and the concentration of Si in LSA layer was estimated to be 10.5 wt.% maximum. When the energy density was
equal to or greater than 147 W mm−2, cellular grained structure with no crack was formed. No iron silicate was observed and alpha iron content in LSA layers
increased. Si concentration within LSA layers was estimated to be 5 to 9 wt.% on average. Crack-free as-deposited samples
exhibited no distinct corrosion resistance. The segregation of Si was confirmed along the grain boundaries and inside the
grains. The microstructure of these samples changed with solution-annealing and the corrosion resistance was fairly improved
with the time period of solution-annealing.
Received: 2 September 1999 / Accepted: 6 September 1999 / Published online: 1 March 2000 相似文献