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1.
Ultrashort-pulse laser ablation of indium phosphide in air 总被引:4,自引:0,他引:4
J. Bonse J.M. Wrobel J. Krüger W. Kautek 《Applied Physics A: Materials Science & Processing》2001,72(1):89-94
Ablation of indium phosphide wafers in air was performed with low repetition rate ultrashort laser pulses (130 fs, 10 Hz)
of 800 nm wavelength. The relationships between the dimensions of the craters and the ablation parameters were analyzed. The
ablation threshold fluence depends on the number of pulses applied to the same spot. The single-pulse ablation threshold value
was estimated to be φth(1)=0.16 J/cm2. The dependence of the threshold fluence on the number of laser pulses indicates an incubation effect. Morphological and
chemical changes of the ablated regions were characterized by means of scanning electron microscopy and Auger electron spectroscopy.
Received: 30 May 2000 / Accepted: 31 May 2000 / Published online: 23 August 2000 相似文献
2.
M. Mosbacher H.-J. Münzer J. Zimmermann J. Solis J. Boneberg P. Leiderer 《Applied Physics A: Materials Science & Processing》2001,72(1):41-44
We report on the role of local optical field enhancement in the neighborhood of particles during dry laser cleaning (DLC)
of silicon wafer surfaces. Samples covered with spherical colloidal particles (PS, SiO2) and arbitrarily shaped Al2O3 particles with diameters from 320–1700 nm were cleaned using laser pulses with durations from 150 fs to 6.5 ns and wavelengths
ranging from 400–800 nm. Cleaned areas were investigated with scanning electron and atomic force microscopy. Holes in the
substrate with diameters of 200–400 nm and depths of 10–80 nm, depending on the irradiation conditions, were found at the
former positions of the particles. For all pulse durations analyzed (fs, ps, ns), holes are created at laser fluences as small
as the threshold fluence. Calculations of the optical field intensities in the particles’ neighbourhood by applying Mie theory
suggest that enhancement of the incident laser intensity in the near field of the particles is responsible for these effects.
DLC for sub-ns pulses seems to be governed by the local ablation of the substrate rather than by surface acceleration.
Received: 31 May 2000 / Accepted: 7 September 2000 / Published online: 22 November 2000 相似文献
3.
Second-harmonic generation (SHG) in atmospheric-pressure air is experimentally studied using single focused linear-polarized
Ti:sapphire intense femtosecond laser pulses at 810 nm. The efficiency of SHG is found to reach a maximum at the optical breakdown
threshold of ≈2.9×1014 W/cm2. The spectral distribution and polarization property of the second harmonic are investigated. The contribution to SHG from
electric-field-induced third-order mixing plays the main role even after the optical breakdown had occurred.
Received: 23 May 2000 / Published online: 16 August 2000 相似文献
4.
F. Machalett K. Edinger J. Melngailis M. Diegel K. Steenbeck E. Steinbeiss 《Applied Physics A: Materials Science & Processing》2000,71(3):331-335
For direct writing of electrically conducting connections and areas into insulating gold oxide thin films a scanning Ar+ laser beam and a 30 keV Ga+ focused ion beam (FIB) have been used. The gold oxide films are prepared by magnetron sputtering under argon/oxygen plasma.
The patterning of larger areas (dimension 10–100 μm) has been carried out with the laser beam by local heating of the selected
area above the decomposition temperature of AuOx (130–150 °C). For smaller dimensions (100 nm to 10 μm) the FIB irradiation could be used. With both complementary methods
a reduction of the sheet resistance by 6–7 orders of magnitude has been achieved in the irradiated regions (e.g. with FIB
irradiation from 1.5×107 Ω/□ to approximately 6 Ω/□). The energy-dispersive X-ray analysis (EDX) show a considerably reduced oxygen content in the
irradiated areas, and scanning electron microscopy (SEM), as well as atomic force microscopy (AFM) investigations, indicate
that the FIB patterning in the low-dose region (1014 Ga+/cm2) is combined with a volume reduction, which is caused by oxygen escape rather than by sputtering.
Received: 30 May 2000 / Accepted: 31 May 2000 / Published online: 13 July 2000 相似文献
5.
E. Sicard C. Boulmer-Leborgne C. Andreazza-Vignolle M. Frainais 《Applied Physics A: Materials Science & Processing》2001,73(1):55-60
The excimer laser nitriding process reported is developed to enhance the mechanical and chemical properties of aluminum alloys.
An excimer laser beam is focused onto the alloy surface in a cell containing 1-bar nitrogen gas. A vapor plasma expands from
the surface and a shock wave dissociates and ionizes nitrogen. It is assumed that nitrogen from plasma in contact with the
surface penetrates to some depth. Thus it is necessary to work with a sufficient laser fluence to create the plasma, but this
fluence must be limited to prevent laser-induced surface roughness. The nitrogen-concentration profiles are determined from
Rutherford backscattering spectroscopy and scanning electron microscopy coupled to energy-dispersive X-ray analysis. Crystalline
quality is evidenced by an X-ray diffraction technique. Transmission electron microscopy gives the in-depth microstructure.
Fretting coefficient measurements exhibit a lowering for some experimental conditions. The polycrystalline nitride layer obtained
is several micrometers thick and composed of a pure AlN (columnar microstructure) top layer (200–500 nm thick) standing on
an AlN (grains) in alloy diffusion layer. From the heat conduction equation calculation it is shown that a 308-nm laser wavelength
would be better to increase the nitride thickness, as it corresponds to a weaker reflectance R value for aluminum.
Received: 17 October 2000 / Accepted: 19 October 2000 / Published online: 23 May 2001 相似文献
6.
Carbon nitride nanocrystals were prepared using a pulsed laser induced liquid–solid interfacial reaction and transmission
electron microscopy, while high resolution electron microscopy characterized their morphology and structure. It is important
that the cubic-C3N4 phase was observed. The formation mechanism of the carbon nitride nanocrystals is also discussed.
Received: 23 May 2000 / Accepted: 26 May 2000 / Published online: 2 August 2000 相似文献
7.
Yinzhong Wu Wei Jia Ching-yue Wang Minglie Hu Xiaochang Ni Lu Chai 《Optical and Quantum Electronics》2007,39(14):1223-1229
Vertical micro-holes were fabricated inside a photosensitive glass (FOTURAN) by focused femtosecond laser (λ = 775 nm) writing,
followed by heat treatment and wet chemical etching in 8% hydrofluoric acid solution for 50 min. The micro-holes were analyzed
by optical and scanning electron microscopy, and was found they own circular cross-section and clear edge. At present, micro-holes
with aspect ratio of about 7 is achieved. By varying the incident laser fluence in a range of 2.3–36.2 J/cm2 and the laser writing velocity in 100–1000 μm/s, the influences of femtosecond laser parameters on the formation of micro-holes
are characterized as that: writing velocities hardly affect the micro-hole diameter, while relatively lower laser fluences
result in smaller diameter, and the cross-section is more circular in this case. The possible reason for this phenomenon is
discussed. 相似文献
8.
Laser micromachining of transparent materials is an intensively studied research area from the point of view of microoptical
element fabrication. One of the most promising indirect processing methods is the laser-induced back-side dry etching (LIBDE).
During this method, transparent targets are contacted with solid thin layers, which absorb and transform the pulse energy
resulting in etching. The applicability of LIBDE technology for processing of fused silica using a visible nanosecond dye
laser (λ=500 nm, FWHM=11 ns) and a 100-nm-thick aluminium absorbing layer was investigated. The applied fluence was varied
in the range of 0–3050 mJ/cm2; the illuminated area was 0.1 mm2. The threshold fluence of the LIBDE etching of fused silica was found to be approximately 540 mJ/cm2. The chemical composition of the surface layers on and around the etched holes was investigated by field-emission scanning
electron microscopy and energy-dispersive X-ray spectrometry. It was found that on average 0.4±0.3 at. % aluminium is built
into the upper ∼1-μm-thick volume of the illuminated fused silica, while the aluminium content fell below the detection limit
in the case of the original surface. Our experiments proved that the LIBDE procedure is suitable for microprocessing of transparent
materials using visible nanosecond laser light.
PACS 42.62.-b; 61.80.Ba; 81.16.Rf; 81.65.Cf 相似文献
9.
D. Voigt E.C. Schilder R.J.C. Spreeuw H.B. van Linden van den Heuvell 《Applied physics. B, Lasers and optics》2001,72(3):279-284
We have characterized a semiconductor amplifier laser system which provides up to 200 mW output after a single-mode optical
fiber at 780 nm wavelength. The system is based on a tapered semiconductor gain element, which amplifies the output of a narrow-linewidth
diode laser. Gain and saturation are discussed as a function of operating temperature and injection current. The spectral
properties of the amplifier are investigated with a grating spectrometer. Amplified spontaneous emission (ASE) causes a spectral
background with a width of 4 nm FWHM. The ASE background was suppressed to below our detection limit by a proper choice of
operating current and temperature and by sending the light through a single-mode optical fiber. The final ASE spectral density
was less than 0.1 nW/MHz, i.e. less than 0.2% of the optical power. Related to an optical transition linewidth of Γ/2π=6 MHz
for rubidium, this gives a background suppression of better than -82 dB. An indication of the beam quality is provided by
the fiber coupling efficiency of up to 59%. The application of the amplifier system as a laser source for atom-optical experiments
is discussed.
Received: 8 May 2000 / Revised version: 21 September 2000 / Published online: 7 February 2001 相似文献
10.
N. G. Semaltianos W. Perrie P. French M. Sharp G. Dearden S. Logothetidis K. G. Watkins 《Applied Physics A: Materials Science & Processing》2009,94(4):999-1009
Femtosecond laser (180 fs, 775 nm, 1 kHz) ablation characteristics of the nickel-based superalloy C263 are investigated. The
single pulse ablation threshold is measured to be 0.26±0.03 J/cm2 and the incubation parameter ξ=0.72±0.03 by also measuring the dependence of ablation threshold on the number of laser pulses.
The ablation rate exhibits two logarithmic dependencies on fluence corresponding to ablation determined by the optical penetration
depth at fluences below ∼5 J/cm2 (for single pulse) and by the electron thermal diffusion length above that fluence. The central surface morphology of ablated
craters (dimples) with laser fluence and number of laser pulses shows the development of several kinds of periodic structures
(ripples) with different periodicities as well as the formation of resolidified material and holes at the centre of the ablated
crater at high fluences. The debris produced during ablation consists of crystalline C263 oxidized nanoparticles with diameters
of ∼2–20 nm (for F=9.6 J/cm2). The mechanisms involved in femtosecond laser microprocessing of the superalloy C263 as well as in the synthesis of C263
nanoparticles are elucidated and discussed in terms of the properties of the material. 相似文献
11.
S.I. Dolgaev S.V. Lavrishev A.A. Lyalin A.V. Simakin V.V. Voronov G.A. Shafeev 《Applied Physics A: Materials Science & Processing》2001,73(2):177-181
The formation and development of the large-scale periodic structures on a single crystal Si surface are studied upon its evaporation
by pulsed radiation of a copper vapor laser (wavelength of 510.6 nm, pulse duration of 20 ns). The development of structures
occurs at a high number of laser shots (∼104) at laser fluence of 1–2 J/cm2 below optical breakdown in a wide pressure range of surrounding atmosphere from 1 to 105 Pa. The structures are cones with angles of 25, which grow towards the laser beam and protrude above the initial surface
for 20–30 μm. It is suggested that the spatial period of the structures (10–20 μm) is determined by the capillary waves period
on the molten surface. The X-ray diffractometry reveals that the modified area of the Si substrate has a polycrystalline structure
and consists of Si nanoparticles with a size of 40–70 nm, depending on the pressure of surrounding gas. Similar structures
are also observed on Ge and Ti.
Received: 12 February 2000 / Accepted: 28 March 2000 / Published online: 20 June 2001 相似文献
12.
E.G. Gamaly A.V. Rode A. Perrone A. Zocco 《Applied Physics A: Materials Science & Processing》2001,73(2):143-149
We present two sets of experimental results on the ablation-rate decrease with increase of the number of consecutive laser
pulses hitting the same spot on the target surface. We have studied laser ablation of a carbon target with nanosecond pulses
in two different interaction regimes: one with a XeCl laser (λ=308 nm) and the other with a Nd:YAG laser (λ=1064 nm), in both
cases at the intensity ∼5×108 W/cm2 Two different mechanisms were found to be responsible for the ablation-rate decrease; they are directly related to the two
different laser–matter interaction regimes. The UV-laser interaction is in the regime of transparent vapour (surface absorption).
The increase of the neutral vapour density in the crater produced by the preceding laser pulses is the main reason for the
decrease of ablation rate. With the IR laser each single laser pulse interacts with a partially ionised plume. With increase
of the number of pulses hitting the same spot on the target surface, the laser–matter interaction regime gradually changes
from the near-surface absorption to the volume absorption, resulting in the decrease in absorption in the target and thus
in the decrease in the ablation rate. The change in the evaporation rate was considered for both vacuum and reactive-gas environments.
Received: 21 February 2001 / Accepted: 26 February 2001 / Published online: 23 May 2001 相似文献
13.
Linear and nonlinear absorptance in Al2O3 films of different optical thicknesses are investigated using an ArF laser calorimeter. While the linear absorptance at 193
nm shows the expected linear increase, nonlinear absorptance increases quadratically with increasing film thickness. Thus,
it cannot be described by a constant nonlinear absorption coefficient β. The experimental findings are explained by a simple
phenomenological approach using excited states with a finite interaction length longer than the actual film thickness. a new
material constant Γ is introduced, which describes the nonlinear absorptance behavior correctly.
Received: 19 May 2000 / Accepted: 22 May 2000 / Published online: 13 July 2000 相似文献
14.
In this work, the excimer-laser-induced crystallization of a-Si films on SiO2 was investigated using a long-pulse-duration (200 ns) XeCl source. The microstructural analysis of the laser-irradiated area,
for incident energy densities comprised between the thresholds corresponding to the surface and full melting, respectively,
of the Si layer, was performed by scanning electron microscopy and Raman spectroscopy. A super-lateral-growth regime was evidenced
quite comparable to that which occurs when classical excimer laser pulses of short duration (≈20 ns) are used. A numerical
simulation of the surface melt dynamics was also performed and compared to the experimental observations.
Received: 8 February 1999 / Accepted: 15 February 1999 / Published online: 5 May 1999 相似文献
15.
Michal Novotn?? P??emysl Fitl Anna Krasilnikova Sytchkova Ji???- Bul?-?? Jan Lanaok Petr Pokorna David Najdek Jia Boan 《Central European Journal of Physics》2009,7(2):327-331
The effect of pulsed laser treatment of metal, and metal blacks, was studied. Gold and black gold thin films were fabricated
by thermal evaporation of gold in a vacuum and nitrogen atmosphere respectively. Black gold films were grown in a nitrogen
atmosphere at pressures of 200 Pa and 300 Pa. UV pulsed laser radiation (λ = 266 nm, τ = 4 ns), with fluence ranging from 1 mJ·cm−2 to 250 mJ·cm−2 was used for the film treatment in a vacuum and nitrogen atmosphere. The nitrogen pressure was varied up to 100 kPa. Surface
structure modifications were analyzed by optical microscopy, atomic force microscopy (AFM) and scanning electron microscopy
(SEM). Energy dispersive X-ray spectroscopy (EDX) was used for chemical characterization of the samples. A significant dependence
of the film optical and structural properties on laser treatment conditions (laser fluence, ambient pressure and number of
applied pulses) was found. The threshold for observable damage and initiation of changes of morphology for gold and black
gold surfaces was determined. Distinct modifications were observed for fluences greater than 106 mJ·cm−2 and 3.5 mJ·cm−2 for the gold and black gold films respectively. Absorbtivity of the black gold film is found to decrease with an increase
in the number of laser pulses. Microstructural and nanostructural modifications after laser treatment of the black gold film
were observed. EDX analysis revealed that no impurities were introduced into the samples during both the deposition and laser
treatment.
相似文献
16.
Asmiet Ramizy Khalid Omar Z. Hassan Omar Alattas 《Journal of nanoparticle research》2011,13(12):7139-7148
Nanostructured GaN layers are fabricated by laser-induced etching processes based on heterostructure of n-type GaN/AlN/Si grown on n-type Si(111) substrate. The effect of varying laser power density on the morphology of GaN nanostructure layer is observed.
The formation of pores over the structure varies in size and shape. The etched samples exhibit dramatic increase in photoluminescence
intensity compared to the as-grown samples. The Raman spectra also display strong band at 522 cm−1 for the Si(111) substrate and a small band at 301 cm−1 because of the acoustic phonons of Si. Two Raman active optical phonons are assigned h-GaN at 139 and 568 cm−1 due to E2 (low) and E2 (high), respectively. Surface morphology and structural properties of nanostructures are characterized
using scanning electron microscopy and X-ray diffraction. Photoluminance measurement is also taken at room temperature by
using He–Cd laser (λ = 325 nm). Raman scattering is investigated using Ar+ Laser (λ = 514 nm). 相似文献
17.
M. Jasińska A. Nowak J.W. Łukaszewicz G. Śliwiński 《Applied Physics A: Materials Science & Processing》2008,92(1):211-215
The surface discoloration due to laser cleaning was investigated for a historical Gotland sandstone. The difference in discoloration
for cleaning performed in air and in the shielding environment of N2 flowing at low velocities was studied by means of colorimetry and scanning electron microscopy and energy dispersive X-ray
spectroscopy techniques. For ablative removal of the natural as well as artificially applied encrustation a pulsed 1064-nm
laser operated at a fluence of 0.5 J/cm2 was applied. It was observed that the natural colour variations (ΔL*=21; Δb*=23) of the stone can completely screen the laser-induced changes. Under conditions of shielding with nitrogen, darkening
and yellowing slightly stronger than those occurring in the ambient air were revealed for the laser-cleaned, artificially
crusted samples and the effect was independent of the gas-flow velocity. The observed difference confirmed the contribution
of iron oxidation to the laser-induced yellowing and showed that the presence of oxygen in the ambient air affects favourably
the cleaning by supporting removal of a variety of combustible surface remnants and crust components of organic as well as
inorganic origin.
PACS 42.62.-b; 52.70.Kz; 81.65.Cf 相似文献
18.
L. C. Nistor J. Van Landuyt V. G. Ralchenko T. V. Kononenko E. D. Obraztsova V. E. Strelnitsky 《Applied Physics A: Materials Science & Processing》1994,58(2):137-144
The post-growth modification of diamond-like amorphous hydrogenated carbon a-C:H films by laser treatment has been studied by transmission electron microscopy and Raman spectroscopy. a-C:H films grown on Si substrates by benzene decomposition in a rf glow discharge were irradiated with 15 ns pulses of a KrF-excimer laser with fluences in the range of E=50–700 mJ/cm2. At fluences below 100 mJ/cm2 an increase in the number of graphitic clusters and in their ordering was evidenced from Raman spectra, while the film structure remained amorphous according to electron microscopy and electron diffraction observations. At higher fluences the appearance of diamond particles of 2–7 nm size, embedded into the lower crystallized graphitic matrix, was observed and simultaneously a progressive growth of graphite nanocrystals with dimensions from 2 nm to 4 nm was deduced from Raman measurements. The maximum thickness of the crystallized surface layer (400 nm) and the degree of laser annealing are limited by the film ablation which starts at E>250 mJ/cm2. The laser-treated areas lose their chemical inertness. In particular, chemical etching in chromium acid becomes possible, which may be used for patterning the highly inert carbon films. 相似文献
19.
Evolution of the deposition rate during pulsed laser deposition of hydroxyapatite coatings and its relation with target morphology 总被引:1,自引:0,他引:1
J.M. Fernández-Pradas L. Clèries P. Serra G. Sardin J.L. Morenza 《Applied Physics A: Materials Science & Processing》2001,72(5):613-618
The evolution of the deposition rate during pulsed laser deposition of hydroxyapatite coatings with a KrF excimer laser was
studied. This evolution was related to the changes produced on the target morphology during laser irradiation. Laser fluences
in the 1.0–5.2 J/cm2 range, typical for the deposition of hydroxyapatite coatings, were investigated. Deposition rates were measured through a
quartz-crystal microbalance, and the target surface was observed by scanning electron microscopy. At the lowest fluences,
the deposition rate decreases as the number of pulses increases. At the same time, a cone structure is developed on the target
surface. At the highest fluences, the deposition rate increases with the number of pulses. In this case, the target surface
becomes rough but cones are not formed. In all cases, an enlargement of the effective irradiated area results. This enlargement
produces the effect of fluence dilution and also an increase of the emitting area. These opposite effects could account for
the different evolutions found for the deposition rate. At low fluences the effect of fluence dilution would predominate over
the increase of the emitting area, and at high fluences the second effect would predominate over the first.
Received: 28 September 2000 / Accepted: 4 October 2000 / Published online: 10 January 2001 相似文献
20.
F.E. Livingston P.M. Adams H. Helvajian 《Applied Physics A: Materials Science & Processing》2007,89(1):97-107
Previous studies in our laboratory have reported that the chemical etch rate of a commercial photosensitive glass ceramic
(FoturanTM, Schott Corp., Germany) in dilute hydrofluoric acid is strongly dependent on the incident laser irradiance during patterning
at λ=266 nm and λ=355 nm. To help elucidate the underlying chemical and physical processes associated with the laser-induced
variations in the chemical etch rate, several complimentary techniques were employed at various stages of the UV laser exposure
and thermal treatment. X-ray diffraction (XRD) was used to identify the crystalline phases that are formed in Foturan following
laser irradiation and annealing, and monitor the crystalline content as a function of laser irradiance at λ=266 nm and λ=355 nm.
The XRD results indicate the nucleation of lithium metasilicate (Li2SiO3) crystals as the exclusive phase following laser irradiation and thermal treatment at temperatures not exceeding 605 °C.
The XRD studies also show that the Li2SiO3 density increases with increasing laser irradiance and saturates at high laser irradiance. For our thermal treatment protocol,
the average Li2SiO3 crystal diameters are 117.0±10.0 nm and 91.2±5.8 nm for λ=266 nm and λ=355 nm, respectively. Transmission electron microscopy
(TEM) was utilized to examine the microscopic structural features of the lithium metasilicate crystals. The TEM results reveal
that the growth of lithium metasilicate crystals proceeds dendritically, and produces Li2SiO3 crystals that are ∼700–1000 nm in length for saturation exposures. Optical transmission spectroscopy (OTS) was used to study
the growth of metallic silver clusters that act as nucleation sites for the Li2SiO3 crystalline phase. The OTS results show that the (Ag0)x cluster concentration has a dependence on incident laser irradiance that is similar to the etch rate ratios and Li2SiO3 concentration. A comparison between the XRD and optical transmission results and our prior etch rate results show that the
etch rate contrast and absolute etch rates are dictated by the Li2SiO3 concentration, which is in turn governed by the (Ag0)x cluster concentration. These results characterize the relationship between the laser exposure and chemical etch rate for
Foturan, and permit a more detailed understanding of the photophysical processes that occur in the general class of photostructurable
glass ceramic materials. Consequently, these results may also influence the laser processing of other photoactive materials.
PACS 42.62.-b; 61.43.Fs; 81.05.Kf; 81.10.-h; 83.80.Ab 相似文献