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1.
The morphology of pentacene organic thin films deposited on SiO2 and Au(111) surfaces using organic molecular beam deposition (OMBD) has been characterized by a multi-technique approach.
Among the techniques applied were X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), scanning electron
microscopy (SEM) and thermal desorption spectroscopy (TDS). Our rather detailed studies reveal that on both substrates the
growth is strongly influenced by dewetting and islanding phenomena, yielding very rough surfaces. Surprisingly, substantial
changes in the morphology were observed also after deposition on room-temperature samples on a time scale of several hours.
The rather extensive set of in situ XPS data was analyzed in the framework of a simple model, which allows us to derive rather
detailed information on the roughness parameters. 相似文献
2.
S. Canulescu T. Lippert A. Wokaun 《Applied Physics A: Materials Science & Processing》2008,93(3):771-778
The mass distributions of the species generated by laser ablation from a La0.6Ca0.4MnO3 target using laser irradiation wavelengths of 193 nm, 266 nm and 308 nm have been investigated with and without a synchronized
gas pulse of N2O. The kinetic energies of the species are measured using an electrostatic deflection energy analyzer, while the mass distributions
of the species were analyzed with a quadrupole mass filter.
In vacuum (pressure 10−7 mbar), the ablation plume consists of metal atoms and ions such as La, Ca, Mn, O, LaO, as well as multiatomic species, e.g.
LaMnO+. The LaO+ diatomic species are by far the most intense diatomic species in the plume, while CaO and MnO are only detected in small
amounts.
The interaction of a reactive N2O gas pulse with the ablation plume leads to an increase in plume reactivity, which is desired when thin manganite films are
grown, in order to incorporate the necessary amount of oxygen into the film. The N2O gas pulse appears to have a significant influence on the oxidation of the Mn species in the plume, and on the creation of
negative ions, such as LaO−,O− and O2−. 相似文献
3.
This work investigates pulsed laser ablation for Ga2O3 nanoparticles. Nanoparticles with diameters of 10 to 500 nm were deposited on silicon substrates in large quantities, by KrF excimer laser ablation of a GaN (99.99% purity) target in high purity nitrogen (99.9995%) background gas at room temperature, without a catalyst. The particle size and phase structure of the as-deposited nanoparticles are examined by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), and selected-area electron diffraction (SAD). FE-SEM images show that the nanoparticles aggregate to form micron-size nanoclusters at chamber pressures of 1 and 5 Torr. On the other hand, nanoparticles aggregate with chain-like nanostructures, are synthesized at high chamber pressures (10 Torr). TEM images further reveal that chain-like nanostructures are formed by the aggregation of individual spherical and ellipsoidal nanoparticles. Photoluminescence measurement shows stable and broad blue emission at 445 nm. PACS 81.20.-N; 81.15.Fg; 75.50.Vv 相似文献
4.
Masaki Oba Yoichiro Maruyama Katsuaki Akaoka Masabumi Miyabe Ikuo Wakaida 《Applied Physics A: Materials Science & Processing》2010,101(3):545-549
Emission characteristics of gadolinium (Gd) oxide are studied, using ns and fs laser pulses for ablation in double-pulse laser
induced breakdown spectroscopy (LIBS). In the current conditions of pulse energy and signal detection timing, emission intensity
enhancement in the reheating mode is 25-fold, but little effect can be observed in a pre-pulse mode. It is shown that the
optimum focus position of the ablation pulse is about 5 mm apart from the sample surface in the reheating mode. Although little
emission can be observed in the single-pulse configuration with fs ablation pulses, the intense emission can be observed in
the reheating mode in the double-pulse configuration. 相似文献
5.
K.?Sudheendran M.?Ghanashyam?Krishna K.?C.?James?Raju 《Applied Physics A: Materials Science & Processing》2009,95(2):485-492
Bismuth Zinc niobate (Bi1.5Zn1.0Nb1.5O7) thin films were deposited by pulsed laser deposition (PLD) method on fused silica substrates at different oxygen pressures.
The structural, microwave dielectric and optical properties of these thin films were systematically studied for both the as-deposited
and the annealed films at 600°C. The as-deposited films were all amorphous in nature but crystallized on annealing at 600°C
in air. The surface morphology as studied by atomic force microscopy (AFM) reveals ultra-fine grains in the case of as-deposited
thin films and cluster grain morphology on annealing. The as-deposited films exhibit refractive index in the range of 2.36–2.53
(at a wavelength of 750 nm) with an optical absorption edge value of 3.30–3.52 eV and a maximum dielectric constant of 11
at 12.15 GHz. On annealing the films at 600°C they crystallize to the cubic pyrochlore structure accompanied by an increase
in band gap, refractive index and microwave dielectric constant. 相似文献
6.
V. E. Rogalin O. M. Kugaenko E. E. Ashkinazi M. S. Andreeva S. A. Filin 《Bulletin of the Russian Academy of Sciences: Physics》2016,80(12):1489-1493
Comprehensive microstructure studies of the surfaces of duralumin sheets exposed to an intense microsecond СО2 laser pulse (Е ~ 500 J) are performed for the first time. The irradiated area is ~100 cm2. A pulse with a duration of ~5 μs has an ~200 ns leading peak. Passivated duralumin sheets subjected to pressure and thermal treatment resulting in the formation of Al2O3 layers ~7 μm thick are irradiated. Electron and atomic force microscopy, X-ray spectral analysis, and optical profilometry are used in the study. Detected traces of nonequilibrium evaporation contained a polycrystalline aggregate of several stoichiometric and nonstoichiometric phases of aluminum oxide and its compounds with manganese and magnesium. 相似文献
7.
T. Kobayashi T. Kato Y. Matsuo M. Kurata-Nishimura Y. Hayashizaki J. Kawai 《Applied Physics A: Materials Science & Processing》2008,92(4):777-780
By ablating solid C60 with a laser pulse, we observe various processes such as the prompt- and the delayed-ionization of C60, the fragmentation into molecular ions and the formation of cluster ions. We found these processes show distinct dependences
on the temporal pulse width, the power and the wavelength of the ablation laser. From the observations, we could confirm efficient
coupling of laser energy to C60 through the molecular absorption even with a laser pulse width less than the electron-phonon coupling time of the C60 molecule. 相似文献
8.
Composite polymer electrolyte systems composed of poly(methyl methacrylate) (PMMA) as the host polymer, lithium trifluoromethanesulphonate
(also known as lithium triflate; LiCF3SO3) as dopant salt, and a variety of different concentrations of nano-sized fumed silica (SiO2) as inorganic filler were studied. The effect upon addition of SiO2 on the ionic conductivity of the composite polymer electrolytes was investigated, and it was proven that the ionic conductivity
had been enhanced. In addition, the interfacial stability also showed improvement. Maximum conductivity was obtained upon
addition of 2 wt.% SiO2. The complexation of PMMA and LiCF3SO3 was verified through Fourier transform infrared studies. The thermal stability of the polymer electrolytes was also found
to improve after dispersion of inorganic filler. This was proven in the thermogravimetric studies. 相似文献
9.
Balsam M. Mirdan Luca Antonelli Dimitri Batani Rashida Jafer Katarzyna Jakubowska Saad al Tarazi 《辐射效应与固体损伤》2013,168(7):610-619
The interaction of 40 ps pulse duration laser emitting at 532 nm wavelength with human dental tissue (enamel, dentin, and dentin–enamel junction) has been investigated. The crater profile and the surface morphology have been studied by using a confocal auto-fluorescence microscope (working in reflection mode) and a scanning electron microscope. Crater profile and crater morphology were studied after applying consecutive laser pulses and it was found that the ablation depth increases with the number of consecutive pulses, leaving the crater diameter unchanged. We found that the thermal damage is reduced by using short duration laser pulses, which implies an increased retention of restorative material. We observe carbonization of the irradiated samples, which does not imply changes in the chemical composition. Finally, the use of 40 ps pulse duration laser may become a state of art in conservative dentistry. 相似文献
10.
A. Langner M. Knez F. Müller U. Gösele 《Applied Physics A: Materials Science & Processing》2008,93(2):399-403
An approach is presented which is capable of fabricating arbitrarily shaped three-dimensional microstructures. Two methods—namely,
macroporous silicon and atomic layer deposition—are combined to realize structures in the micrometer and submicrometer range.
Using TiO2 as an example, the fabrication of single hollow objects as well as complex network structures is shown. The scalability and
the wide range of applicable materials are the key points of this method for future applications. 相似文献
11.
Cryogenic temperature operation of a 〈010〉-cut microchip Tm,Ho:Lu2SiO5 laser end-pumping by a fiber-coupled laser-diode is presented. A 2.73 W absorbed pump power is used to generate a maximum
laser output of 470 mW, representing a 17.2% optical-to-optical conversion efficiency and a 61.7% slope efficiency corresponding
to absorbed power. In the experiment, the oscillating wavelength shifting from 2.03 to 2.08 μm has been observed and a single
2.03 μm wavelength oscillation has obtained. To our knowledge, this work is the first time to investigate the Cryogenic temperature
operation of microchip Tm,Ho:Lu2SiO5. 相似文献
12.
Cheng-Fu Yang Hong-Hsin Huang Cheng-Yi Chen Ping-Chih Huang Chien-Chen Diao 《Applied Physics A: Materials Science & Processing》2009,94(1):117-122
In this study, two different thin films, TiO2 thin film and TiO2–W–TiO2 multi-layer thin films (W, tungsten), are prepared by RF magnetron sputtering onto glass substrates. The crystal structure,
morphology, and transmittance of TiO2 and TiO2–W–TiO2 multi-layer thin films are investigated by X-ray diffraction, SEM, and UV-Vis spectrometer, respectively. The amorphous,
rutile, and anatase TiO2 phases are observed in the TiO2 thin film and in the TiO2–W–TiO2 multi-layer thin films. The deposition of tungsten as the inter-layer will have large effect on the transmittance and phase
ratios of rutile and anatase phases in the TiO2–W–TiO2 multi-layer thin films. The crystal intensities of amorous TiO2 will decrease as the tungsten is used as the middle layer in the multi-layer structure. The band gap energy values of TiO2 thin film and TiO2–W–TiO2 multi-layer thin films are evaluated from (αhν)1/2 versus energy plots, and the calculated results show that the energy gap decreases from 3.21 eV (TiO2 thin film) to 3.08∼3.03 EV (TiO2–W–TiO2 multi-layer thin films). 相似文献
13.
D. A. Zayarny A. A. Ionin S. I. Kudryashov S. V. Makarov A. A. Kuchmizhak O. B. Vitrik Yu. N. Kulchin 《JETP Letters》2016,103(12):752-755
Single-shot thresholds of surface ablation of aluminum and silicon via spallative ablation by infrared (IR) and visible ultrashort laser pulses of variable width τlas (0.2–12 ps) have been measured by optical microscopy. For increasing laser pulse width τlas < 3 ps, a drastic (threefold) drop of the ablation threshold of aluminum has been observed for visible pulses compared to an almost negligible threshold variation for IR pulses. In contrast, the ablation threshold in silicon increases threefold with increasing τlas for IR pulses, while the corresponding thresholds for visible pulses remained almost constant. In aluminum, such a width-dependent decrease in ablation thresholds has been related to strongly diminished temperature gradients for pulse widths exceeding the characteristic electron-phonon thermalization time. In silicon, the observed increase in ablation thresholds has been ascribed to two-photon IR excitation, while in the visible range linear absorption of the material results in almost constant thresholds. 相似文献
14.
G. N. Gerasimov M. M. Grekhov V. F. Gromov M. I. Ikim E. Yu. Spiridonova L. I. Trakhtenberg 《Russian Journal of Physical Chemistry B, Focus on Physics》2018,12(4):709-713
The structural characteristics, valence states, and distribution of cerium ions between the components in In2O3–CeO2 and SnO2–CeO2 nanocomposites fabricated using the impregnation method were studied. X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDX) were used to show that, during impregnation, cerium ions are not included into In2O3 crystals and are disposed only on their surface in the form of nano-sized crystallites or amorphous clusters. On the other side, under the contact of CeO2 clusters with a surface of SnO2 matrix crystals, cerium ions penetrate into the surface layer of these crystals. In contrast to an In2O3–CeO2 system, where the addition of CeO2 does not affect the conduction activation energy, where cerium oxide is added to SnO2, the observed increase in the resistance of a SnO2–CeO2 composite is accompanied by a sufficient increase in activation energy. These data and the XPS spectra confirm the modification of the surface layers of conductive SnO2 crystals as, a result of the penetration of cerium ions into these layers. 相似文献
15.
J. L. Shang T. Zhang H. Wang J. Xie G. J. Hu 《Applied Physics A: Materials Science & Processing》2009,95(3):699-702
Evolution of microstructure and optical property with annealing temperature has been examined for Ba0.9Sr0.1TiO3 films derived from one single precursor solution containing polyethylene glycol polymer. The films sintered below 750°C exhibit
a uniform phase structure across the cross-sections and an ordinary optical thin film feature, while the Ba0.9Sr0.1TiO3 films crystallized at 750°C or higher temperature render a lamellar texture consisting of dense and porous Ba0.9Sr0.1TiO3 layers and a good performance as a one-dimensional photonic crystal. The discrepancy in cross-sectional morphology and reflectance
property observed in these Ba0.9Sr0.1TiO3 films has been preliminarily explained. 相似文献
16.
Y. W. Li Z. G. Hu F. Y. Yue W. Z. Zhou P. X. Yang J. H. Chu 《Applied Physics A: Materials Science & Processing》2009,95(3):721-725
(La0.5Sr0.5)CoO3 (LSCO) thin films have been fabricated on silicon substrate by the pulsed laser deposition method. The effects of substrate
temperature and post-annealing condition on the structural and electrical properties are investigated. The samples grown above
650°C are fully crystalline with perovskite structure. The film deposited at 700°C has columnar growth with electrical resistivity
of about 1.99×10−3 Ω cm. The amorphous films grown at 500°C were post-annealed at different conditions. The sample post-annealed at 700°C and
10−4 Pa has similar microstructure with the sample in situ grown at 700°C and 25 Pa. However, the electrical resistivity of the
post-annealed sample is one magnitude higher than that of the in situ grown sample because of the effect of oxygen vacancy.
The temperature dependence of resistivity exhibits semiconductor-like character. It was found that post-annealing by rapid
thermal process will result in film cracks due to the thermal stress. The results are referential for the applications of
LSCO in microelectronic devices. 相似文献
17.
Y. Q. Zhang J. X. Wang Y. L. Shang Y. L. Song L. Jiang 《Applied Physics A: Materials Science & Processing》2011,102(3):531-536
The acid-base vapors/light double responsive dye-infiltrated SiO2 inverse opal photonic crystals (PCs) were fabricated by sacrificial template method and a subsequent infiltration of spiropyran
derivative dye molecules. The fluorescence of ring-open dye molecules infiltrated in PCs can be switched on/off based on different
fluorescence properties of spiropyran dye under stimuli of acid-base vapors or light, when PCs with suitable stopband were
selected. The fluorescence switch behavior based on PCs has potential applications in data storage, color displays, chemical
and biological sensors. 相似文献
18.
Surasing Chaiyakun Artorn Pokaipisit Pichet Limsuwan Boonlaer Ngotawornchai 《Applied Physics A: Materials Science & Processing》2009,95(2):579-587
Titanium dioxide thin films were deposited on three different unheated substrates by unbalanced magnetron sputtering. The
effects of the sputtering current and deposition time on the crystallization of TiO2 thin films were studied. The TiO2 thin films were deposited at three sputtering current values of 0.50, 0.75, and 1.00 A with different deposition times of 25,
35, and 45 min, respectively. The surface morphology of the films was investigated by atomic force microscopy (AFM). The structure
was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The film thickness was determined
by field emission scanning electron microscopy (FE-SEM), and the optical property was evaluated with spectroscopic ellipsometry.
The results show that polycrystalline anatase films were obtained at a low sputtering current value. The crystallinity of
the anatase phase increases as the sputtering current increases. Furthermore, nanostructured anatase phase TiO2 thin films were obtained for all deposition conditions. The grain size of TiO2 thin films was in the range 10–30 nm. In addition, the grain size increases as the sputtering current and deposition time
increase. 相似文献
19.
Chih-Yuan Lu Patrick J. Shamberger Esmeralda N. Yitamben Kenneth M. Beck Alan G. Joly Marjorie A. Olmstead Fumio S. Ohuchi 《Applied Physics A: Materials Science & Processing》2008,93(1):93-98
Phase transformation of thin film (∼30 nm)In2Se3/Si(111) (amorphous→crystalline) was performed by resistive annealing and the reverse transformation (crystalline→amorphous)
was performed by nanosecond laser annealing. As an intrinsic-vacancy, binary chalcogenide semiconductor, In2Se3 is of interest for non-volatile phase-change memory. Amorphous In
x
Se
y
was deposited at room temperature on Si(111) after pre-deposition of a crystalline In2Se3 buffer layer (0.64 nm). Upon resistive annealing to 380°C, the film was transformed into a γ-In2Se3 single crystal with its {0001} planes parallel to the Si(111) substrate and
parallel to Si
, as evidenced by scanning tunneling microscopy, low energy electron diffraction, and X-ray diffraction. Laser annealing with
20-ns pulses (0.1 millijoules/pulse, fluence≤50 mJ/cm2) re-amorphized the region exposed to the laser beam, as observed with photoemission electron microscopy (PEEM). The amorphous
phase in PEEM appears dark, likely due to abundant defect levels inhibiting electron emission from the amorphous In
x
Se
y
film. 相似文献
20.
GaN thin films grown on sapphire substrates by metalorganic chemical vapor deposition (MOCVD) are successfully bonded and transferred onto Si receptor substrates using fusion bonding and laser lift-off (LLO) technique. GaN/Al_2O_3 structures are joined to Si substrates by pressure bonding Ti/Au coated GaN surface onto Ti/Au coated Si receptor substrates at the temperature of 400℃. KrF excimer laser with 400-mJ/cm~2 energy density, 248-nm wavelength, and 30-ns pulse width is used to irradiate the wafer through the transparent sapphire substrates and separate GaN films from sapphire. Cross-section scanning electron microscopy (SEM) combined with energy dispersive X-ray spectrometer (EDS) measurements show that Au/Si solid solution is formed during bonding process. Atomic force microscopy (AFM) and photoluminescence (PL) measurements show that the qualities of GaN films on Si substrates degrade little after substrates transfer. 相似文献