共查询到20条相似文献,搜索用时 328 毫秒
1.
Received: 4 June 1997/Accepted: 13 June 1997 相似文献
2.
P. Bunton M. Binkley G. Asbury 《Applied Physics A: Materials Science & Processing》1997,65(4-5):411-417
Received: 21 May 1997/Accepted: 4 July 1997 相似文献
3.
K. Chen J. Ihlemann P. Simon I. Baumann W. Sohler 《Applied Physics A: Materials Science & Processing》1997,65(4-5):517-518
3 by short ultraviolet laser pulses (0.5 ps, 248 nm) is presented. Gratings with a period of 360 nm and a modulation depth
of 80 nm are fabricated on the sample surface by single-laser-shot exposure. The structures are projection imaged by a Schwarzschild
objective in air. The modulation depth can be varied by applying multiple-pulse exposure.
Received: 18 July 1997/Accepted: 5 August 1997 相似文献
4.
Resonant Raman studies of surface composition and structural ordering in laser-irradiated Hg1-xCdxTe
1-x CdxTe for x=0.165 and x=0.18. The annealing was performed in air with a Nd:YAG laser tuned to the first harmonic. A pulse duration
of 72 ns and irradiation energy densities of 270 and 400 mJ/cm2 were used. Information on both the structural ordering and the alloy composition in irradiated Hg1-xCdxTe was obtained by resonance Raman spectroscopy with laser photon energies of between 2.41 and 2.54 eV. The presented Raman
spectra from annealed samples indicate structural disorder and a decrease in the degree of alloying as a result of Hg outdiffusion
and segregation caused by laser-induced nonequilibrium melting and solidification. Moreover, a shift of the maximum resonant
enhancement for the TO2, LO2, A, and LO1&TO1 modes in the case of a Hg0.82Cd0.18Te sample, annealed by 400 mJ/cm2 laser pulse, to higher photon energy points to an increase in the composition from x=0.18 to x?0.3.
Received: 14 July 1997/Accepted: 10 October 1997 相似文献
5.
R. Kullmer 《Applied Physics A: Materials Science & Processing》1997,65(3):273-279
3 films were produced by KrF excimer-laser ablation. Films deposited on fused silica substrates were polycrystalline without
preferential orientation and had cubic rather than tetragonal structure. BaTiO3/Au/Ti/fused silica films showed a large dielectric constant, which increased with the thickness of the film, but poor ferroelectric
properties. This behavior seems to be related to the small size of grains. On (100)MgO substrates oriented films were obtained.
BaTiO3/YBa2Cu3O7-δ/(100)MgO films showed a large dielectric constant also and improved ferroelectric properties. Although this indicates a larger
degree of tetragonality, the tetragonal structure of single crystal BaTiO3 has not yet developed. Localized reduction and metallization of BaTiO3/(100)MgO films by means of Ar+-laser radiation was demonstrated. This technique allows to produce conducting patterns in a single-s
tep process.
Received: 6 January 1997/Accepted: 21 April 1997 相似文献
6.
M.M. Ivanenko H. Handreck J. Göthel W. Fuss K.-L. Kompa P. Hering 《Applied physics. B, Lasers and optics》1997,65(4-5):577-582
2 to the CHClF2/He mixture irradiated by a Q-switched CO2 laser leads to oxidation of the dissociation product according to the reaction: CF2+NO2→COF2+NO. The resulting COF2 with a 13C content near 50% is easy to convert to CO2 or CO for further enrichment by a nonlaser process. We measured the dependence of the fraction of dimerised CF2 on NO2 pressure pNO2 and the amount of NO2 required to suppress dimerisation on the dissociation yield. Both agree with a kinetic model using known rate constants.
For the range of the dissociation parameters (13CF2 yield of 10% per pulse, isotope selectivity of 130) of practical interest, 95% of the CF2 produced is oxidized at pNO2≈1/2pCHClF2. In the absence of NO2, major (20%–35%) losses of CF2 at the metal walls of the irradiation system were observed. Addition of NO2 suppresses them. For comparison, we also used O2 as a scavenger in CHClF2 dissociation. NO2 is by orders of magnitude more efficient.
Received: 21 January 1997/Revised version: 23 March 1997 相似文献
7.
V. Trtík F. Sánchez R. Aguiar Y. Maniette C. Ferrater M. Varela 《Applied Physics A: Materials Science & Processing》1998,67(4):455-457
2 (001) epitaxial thin films deposited on Si(001) with yttria-stabilized zirconia buffers have been obtained for the first time
at room temperature by pulsed-laser deposition. The influence of oxygen pressure on the crystal quality of CeO2 was studied for the films deposited at 100 °C. The rocking curve full width at half maximum of the CeO2(002) peak for films deposited at room temperature and 100 °C was between 1° and 2°, for oxygen pressures below 3×10-2 mbar. The best crystal quality was obtained at around 3×10-3 mbar. Epitaxial growth at room temperature was confirmed by cross-sectional transmission electron microscopy. Scanning electron
microscopy and atomic force microscopy revealed very smooth surfaces for oxygen pressure below 3×10-2 mbar, with rms roughness values around 0.3 nm over 5 μm×5 μm.
Received: 25 September 1997/Accepted: 22 April 1998 相似文献
8.
A. Luft U. Franz L. Emsermann J. Kaspar 《Applied Physics A: Materials Science & Processing》1996,63(2):93-101
Holes drilled in metals and silicon using different short-pulse lasers (copper vapour, Nd : YLF and titanium: sapphire) were characterized under optical and electron microscopy. The aim was to analyze and compare the thermal and mechanical effects on materials induced by laser drilling with a wide range of pulse widths (50 ns to 200 fs) and power densities (108 W/cm2 to 1015 W/cm2).Heat affected structural zones around micro-holes drilled in cold-rolled copper were revealed by analyzing ion-polished hole sections in the scanning electron microscope using electron channelling contrast. The heat affected zones were found to have a maximum width of 5 m to 10 m, independent of the duration of the pulses. Mechanically and thermally induced deformations and slip phenomena, including prismatic punching, were observed in laser-drilled molybdenum monocrystals. The dislocation arrangement which developed during laser drilling of silicon monocrystals was visualized by transmission electron microscopy.The microscopic studies showed that for percussion drilling in the high fluence range characterized by high ablation rates of a few micrometres per pulse the use of shorter pulses (H < 50 ns) did not lead to any appreciable reduction in the melt component, material re-deposition or thermal load on the wall of the hole. In addition, the increasing mechanical loads on the material due to the higher pressure in the drill channel becomes a limiting factor for the precision of the processing. 相似文献
9.
H. M. Phillips Yunjun Li Zhaoqi Bi Binglin Zhang 《Applied Physics A: Materials Science & Processing》1996,63(4):347-351
Transparent conducting SnO2 thin films with a thickness between 1000–2000 Å were deposited on glass, quartz and silicon substrates using standard pulsed laser deposition techniques with two different targets (Sri and SnO2) and with three different laser wavelengths (1.06, 0.532 and 0.266 ) from a Q-switched Nd: YAG laser. Tin dioxide films with optical transmission over most of the visible spectrum exceeding 80% were obtained using a Sn target and a background oxygen pressure of 20 Pa. The electrical resistivity () depended strongly on the substrate temperature during deposition, with the lowest values of of about 10–2 -cm obtained when the substrate was maintained at 400°C during deposition. Using SnO2 targets, predominantly amorphous phase SnO2 films were deposited on Si substrates and then transformed into polycrystalline Sn3O4 by laser induced crystallization ( = 1.06 m). Whereas these later films were essentially non-conducting as deposited ( > 400 -cm), the electrical resistivity was permanently reduced after laser induced crystallization by a factor greater than 1000 to a value of approximately 4 × 10–1 -cm. 相似文献
10.
An argon laser is used to induce Laser Chemical Vapor Deposition (LCVD) of platinum using platinum bihexafluoroacetyl-acetonate as precursor. The process can be photolytic or pyrolytic depending on the laser power used. These processes are studied by recording the laser light transmitted through of deposit and substrate. Photolytic deposition takes place either in the adsorbed phase or in the gaseous phase depending on the temperature induced by radiation absorption. The induced-temperature calculation using a model developed by us confirms the experimental results obtained. The influence of the substrate base temperature and the precursor product vapour pressure confirms photolytic deposition from the adsorbed phase for low powers and from the vapour phase onwards for high powers. The deposits obtained present a typical 96% Pt composition and its use in Schottky diode manufacture permit obtaining devices with good characteristics in spite of experimental limitations. 相似文献
11.
S.A. Nepijko R. Wiesendanger 《Applied Physics A: Materials Science & Processing》1997,65(4-5):361-366
Received: 6 June 1997/Accepted: 12 June 1997 相似文献
12.
J. Jersch F. Demming L.J. Hildenhagen K. Dickmann 《Applied Physics A: Materials Science & Processing》1998,66(1):29-34
Received: 8 April 1997/Accepted: 23 June 1997 相似文献
13.
The adsorption of CO on Pt(111) surfaces has been studied under clean conditions by a highly surface sensitive double-beam
infrared reflection spectroscopy (IRS). In contrast to results of other authors two stretching vibrations of adsorbed CO rather
than one are detected near 2100cm−1 and 1870cm−1. This is in agreement with recent findings in high-resolution electron energy loss spectroscopy (ELS). The results are discussed
in terms of two adsorption sites: CO adsorbed in on-top positions and double coordinated on bridging sites, respectively.
Furthermore, a precursor state and a preferential adsorption in islands at low coverage is taken into account. 相似文献
14.
H.-B. Jiang A. Grossmann Th.W. Hänsch 《Applied Physics A: Materials Science & Processing》1998,66(1):119-122
Received: 17 November 1997/Accepted: 18 November 1997 相似文献
15.
R. Pascal C. Zarnitz M. Bode R. Wiesendanger 《Applied Physics A: Materials Science & Processing》1997,65(1):81-83
Received: 5 May 1997/Accepted: 6 May 1997 相似文献
16.
M. Rusu 《Applied Physics A: Materials Science & Processing》1998,66(3):357-361
Received: 1 July 1997/Accepted: 6 August 1997 相似文献
17.
H.M. Lauranto 《Applied physics. B, Lasers and optics》1998,66(2):231-239
Received: 24 March 1997/Revised version: 8 September 1997 相似文献
18.
Received: 15 August 1997/Accepted: 13 November 1997 相似文献
19.
M. Löhndorf A. Wadas R. Wiesendanger 《Applied Physics A: Materials Science & Processing》1997,65(4-5):511-515
Received: 14 August 1997/Accepted: 14 August 1997 相似文献
20.
D.H. Sarkisyan A.S. Sarkisyan A.K. Yalanusyan 《Applied physics. B, Lasers and optics》1998,66(2):241-244
Received: 10 February 1997/Revised version: 16 May 1997 相似文献