bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microtopography of Ion Beam Etched NiP Films.
Authors: Noguchi Kazuhiko , Ueda Ryuzi , Maeyama Yoshitaka 
Published: March 2011

ABSTRACTThe microtopography of NiP films ( P content, 8.7–12wt.%; thickness, 40–50 μm ) prepared by electroless plating on 18–8 stainless steel plates for molds and etched with a 10 keV Ar+ ion beam was studied both by SEM observations and Talystep surface profile measurements. With films containing less than 9.6wt.%P, which is supposed to have a transient structure between the supersaturated solid solution and the amorphous solid, smooth surfaces were obtained down to a few micrometers of etch depth and after that craters were formed. As for the mechanism of crater formation, it is considered that Ni crystallites locally precipitate by ion bombardment and then are etched selectively. With amorphous films containing 10.6wt.%P, microcavities less than 0.02 μmRmax instead of craters were observed regardless of the etch depth. The ion beam etching of NiP films has been found to be very promising for the preparation of precision molds of various grades, e.g. for plastic lenses used in opto-electronics, by selecting P content according to the desired surface roughness and etch depth of a particular application.
Micro-RBS Analysis of Masklessly Fabricated Structures
Authors: Kinomura A. , Takai M. , Matsuo T. , Satou M. , Kiuchi M. , Fujii K. , Namba S. 
Published: March 2011

ABSTRACTRutherford backscattering (RBS) analysis of small-sized structures, fabricated by laser chemical vapor deposition (LCVD) with a focused laser beam and ion implantation with a focused ion beam (FIB), has been performed by a microprobe with focused 1.5 MeV helium ions. Micro-RBS spectra and RBS-mapping images revealed a local distribution of masklessly deposited Mo layers on GaAs and local doses of masklessly implanted Au atoms in Si.
Modelling of Pyrolytic Laser Direct-Writing from Thin Metalorganic Films
Authors: Price Peter E. , Jensen Klavs F. 
Published: March 2011

ABSTRACTA one-dimensional model for pyrolytic laser direct-writing of metal features from thin metalorganic films is presented. The model extends previous results for scanning laser crystallization by including separate but coupled mass and energy balances and allowing for variations in the optical properties and thermal conductivity in the film as it decomposes. A finite element approach is used to obtain solutions to the steady state and transient model forms. The model predicts the existence of multiple steady states for a range of laser powers when the optical absorbance is a nonlinear function of the fractional conversion in the film. These predictions agree qualitatively with multiple steady states that have been observed in direct-writing of palladium features from palladium acetate films. Experimental results that demonstrate multiplicity in the palladium acetate system are presented. The model also predicts the existence of periodic solutions that correspond to the periodic features that have been reported for direct-writing of gold features from organogold films.
Laser-Induced Chemical Vapor Deposition of High Purity Aluminum
Authors: Baum Thomas H. , Larson Carl E. , Jackson Robert L. 
Published: March 2011

ABSTRACTThe laser-induced chemical vapor deposition (LCVD) of aluminum metal has been achieved via the pyrolytic decomposition of trimethylamine aluminum hydride (TMAAH). This material is a volatile, crystalline solid which is non-pyrophoric, in contrast to many other aluminum precursors. Laser-driven pyrolysis of TMAAH enables the selective deposition of high purity, highly conducting aluminum deposits. The volatility of the TMAAH precursor is directly responsible for the rapid rates of aluminum deposition and permits rapid scan velocities to be utilized. The relationship between the chemical structure of TMAAH and the high purity of the aluminum deposits is described.
Ion Beam Processing of Optical Materials
Authors: Williams F. L. , Boyer L. L. , Reicher W. , McNally J. J. , Al-Jumaily G. A. , McNeil J. R. 
Published: March 2011

ABSTRACTWe have deposited thin films of optical materials using ion beam sputtering and ion assisted deposition techniques. It is possible to obtain good quality film material deposited on substrates at temperatures lower than normally required. Ion assisted deposition influences film stoichiometry and packing density, which in turn determine optical and mechanical properties of the film material. We discuss two general indicators which appear helpful in predicting the degree to which these occur.
Patterned Crystal Growth of GaAs by Laser Assisted Atomic Layer Epitaxy
Authors: Iwai Sohachi , Meguro Takashi , Aoyagi Yoshinobu , Namba Susumu 
Published: March 2011

ABSTRACTAtomic layer epitaxy (ALE) of GaAs is achieved by metalorganic vapor phase epitaxy (MOVPE) under irradiation by Ar ion laser. The self-limiting mechanism for gallium deposition at one atomic layer on an arsenic atomic surface is realized by the site-selective decomposition of triethylgallium on the arsenic surface. A patterned growth of ALE is obtained by scanning a laser beam on a substrate.
Laser Patterning of II-VI Epitaxial Thin Films
Authors: Irvine S.J.C. , Hill H. , Hails J.E. , Blackmore G.W. , Mullin J.B. 
Published: March 2011

ABSTRACTThe laser induced photo-MOVPE (photolytic-metal organic vapour phase epitaxy) technique has been used to grow epitaxial films onto CdTe or GaAs substrates (with a 257nm frequency doubled Argon ion laser). The growth temperature was chosen to be below the normal pyrolysis temperature so that decomposition of the metal-organics will only occur within the illuminated parts of the substrate. A measure of enhancement of growth rate by UV illumination is the photo-enhancement factor which has been determined for CdTe deposits onto Si(100) substrates using the precursors dimethyl cadmium (Me2Te) together with either diethyl telluride (Et2Te) or dimethyl ditelluride (Me2Te2). For patterned epitaxial layers at 300°C, Et2Te was preferable to Me2Te2 because Et2Te was more stable, yielding a higher photo-enhancement factor. A 2-D array of CdTe mesas (60 × 60μm) has been deposited onto a GaAs (100) substrate. Using imaging SIMS (secondary ion mass spectrometry) the distribution of major elements and impurities have been studied.
A Comparison of the Gas Phase Processes Resulting from SiH4 and Si2H6 Photodissociation with a Pulsed ArF Excimer Laser
Authors: Boch E. , Fuchs C. , Fogarassy E. , Siffert P. 
Published: March 2011

ABSTRACTWe present in this paper a comparison of the photodissociation processes of SiH4 and Si2H6 under pulsed excimer laser at 193 nm. The experimental curves of the gas composition as a function of laser energy density show that the dissociation of Si2H6 results from both one and two-photon absorption whereas SiH4 only absorbs two photons. The deposition yield of Si2H6 has also been determined as a function of the number of laser pulses or initial pressure. These experimental results show the establishment of a stationary state in the gas phase and prove the existence of reverse reactions in the disilane kinetic model. The photodissociation of Si2H6 under UV laser excitation (193 nm) presents, therefore, similar properties to those of SiH4.
Selective Photochemical Dry Etching of Compound Semiconductors: Enhanced Control Through Secondary Electronic Properties
Authors: Ashby Carol I. H. 
Published: March 2011

ABSTRACTWhen laser-driven etching of a semiconductor requires direct participation of photogenerated carriers, the etching quantum yield will be sensitive to the electronic properties of a specific semiconductor material. The band-gap energy of the semiconductor determines the minimum photon energy needed for carrier-driven etching since sub-gap photons do not generate free carriers. However, only those free carriers that reach the reacting surface contribute to etching and the ultimate carrier flux to the surface is controlled by more subtle electronic properties than the lowestenergy band gap. For example, the initial depth of carrier generation and the probability of carrier recombination between the point of generation and the surface profoundly influence the etching quantum yield. Appropriate manipulation of process parameters can provide additional reaction control based on such secondary electronic properties. Applications to selective dry etching of GaAs and related materials are discussed here.
Mass Spectrometric Probing of Laser-Induced Materials Vapor Transport: Graphite and Superconducting YBa2Cu3Ox
Authors: Bonnell David. W. , Schenck P. K. , Hastie J. W. 
Published: March 2011

ABSTRACTA very high pressure-sampling mass spectrometer has been used to identify the vapor transport species and determine the thermochemistry and kinetics of laser-induced plumes produced from graphite and superconducting composition YBa2Cu3Ox targets (x = 6.5 to 7). An electron impact ion source was used for the ionization and detection of neutral plume species. The plumes initially contain -1 atm (1 atm = 101.325 kPa) of neutral and charged atomic and molecular species in a vacuum of <10−7 atm. Time resolved mass spectra were obtained with graphite targets for the neutral plume species Cn (n = 1-9) for varying laser fluence, laser-surface interaction geometry, vapor plume-sampling geometry, and target surface morphology. Relatively low abundance charged species C1+, C2+, C3+, and impurities Na+ and K+ were also observed in the laser-induced plume.Mass spectra obtained with superconducting YBa2Cu3Ox targets showed a variety of species in the laser-induced plumes including both neutral and ionic Y, Ba, and Cu. In addition, molecular species such as O2, BaO, CuO+, YO and bimetallics (BaCu, YCu) were observed.
Laser-Induced Reactive Evaporation and Condensation
Authors: Chow Gan-Moog , Struti Peter R. 
Published: March 2011

ABSTRACTA study of laser-induced reactive evaporation-condensation is presented. This considers coevaporation of metallic, and non-metallic species, by a cw carbon dioxide laser beam, within a reducing environment (98.5% hydrogen, 1.5% methane). A heated W filament placed in proximity of the laser beam-substrate interaction zone produces W for deposition via chemical vapor transport reactions. Composite thin films of a W matrix containing amorphous silica fibers have been deposited on nickel alloy substrates. These films form at rates of about 1 micron/sec, and are found to be adherent to the substrates. The diameter of the fibers is between 25 nm and 120 nm, depending on the interaction time. Various analytical techniques have been employed to characterize as-synthesized layers. Mechanisms of this process are discussed.
Ablation of Polymers with Pairs of Ultraviolet Laser Pulses with Controlled Temporal Separation
Authors: Braren Bodil , Srinivasan R. 
Published: March 2011

ABSTRACTThe dependance on the pulse width of the ultraviolet laser ablation and etching of poly(methyl methacrylate) was examined using 40-100 ns pulses. These pulses were created by stitching together two identical pulses, each of 40 ns half-width, which were separated by a set time interval from 0 to 380 ns. The etch depth/pulse is sensitive to the pulse width and, therefore, the power density in this polymer.The response of PMMA to etching by pairs of pulses suggests that short-lived species which may be electronic states (e.g., triplets) and/or radicals play an important role in the ablation. The shape of the pulse was also found to influence the etch depth/pulse.The etching of polyimide by these extended pulses shows trends that are opposite to those observed in poly(methyl methacrylate). In this instance the shielding of the latter portion of the incoming pulse by the products that are ablated by the front portion is probably a serious effect.
Ultrathin Silicon Dioxide Films: Photo-Induced Growth
Authors: Boyd Ian W. 
Published: March 2011

ABSTRACTThe reaction of oxygen with silicon induced by intense photon beams at different wavelengths is described. We find different enhancement rates applying to UV and visible radiation, which can be as high as 400% for thin film growth at low temperatures. Often, however, they can be so small that they may be completely overshadowed at high temperatures by the rapid oxidation rates arising from thermal contributions. By using UV radiation projected through a mask to induce low temperature photonic oxidation of silicon, we have grown directly patterned oxide structures dispensing with the need for conventional photolithographic etching.
Reversible Laser Modification of High Temperature Superconducting Y-Ba-Cu-O Films
Authors: Krchnavek Robert R. , Chan Siu-Wai , Rogers C.T. , Rosa F. De , Miceli P.F. , Allen S.J. 
Published: March 2011

ABSTRACTWe describe a reversible technique for locally modifying the oxygen stoichiometry and electrical transport properties of superconducting thin films. A focused argon ion laser beam is scanned across the surface of a YBa2Cu3O7-x thinfilm, contained in a vacuum, at incident power levels well below those necessary for ablation. The change in oxygen stoichiometry is monitored in-situ by the room temperature electrical resistance. We have measured the superconducting properties of these locally modified films. The resulting R vs T curve for the composite structure (film/laserstripe/film) shows the expected double transition. The first transition, corresponding to the unmodified film, occurs at 87 K while the second transition, corresponding to the modified stripe, occurs at a lower temperature and is a function of the laser induced change in the room temperature electrical resistance. The critical current for the composite structure is depressed from the original film. The laser writing can be erasedor bleached out by room temperature exposure to an oxygen plasma.
The Spectroscopy and Surface Chemistry of Metal-Alkyl Molecules
Authors: Shaw P. , O'Neill J. , Sanchez E. , Wu Z. , Osgood R.W. 
Published: March 2011

ABSTRACTmetal-alkyl molecules provied an early source molecule for photodeposition of metal. They continue to be of interest for patterned and unpatterned laser deposition and for conctact formation on compound semiconductors. This article provides a brief review of what has been learned about the surface photo-physic of this class of molecules based on several years of study with uV and iR absorption spectroscopy, UHV surface analysis, and thermal and photodesorption amass spectroscopy.
Pulsed Laser Processing of Targets Immersed in Liquid Media
Authors: Partridge Julian P. , Strutt Peter R. , Klemens Paul G. 
Published: March 2011

ABSTRACTThis report describes a study of the formation of TiN thin films produced by laser irradiation of titanium targets immersed in liquid nitrogen. Three fluence thresholds have been determined, corresponding to: (i) surface melting in gaseous nitrogen (0.7 J/cm2) (ii) surface melting under liquid nitrogen with TiN formation (1.2 J/cm2) and (iii) gross melting accompanied by the generation of periodic surface structures ( >2.0 J/cm2). Data obtained from transmission electron microscopy, Auger spectroscopy, and XPS studies show that the rapid solid-statecooling rates ( l010deg/sec ) result in a supersaturated, twinned hcp structure with solute contents up to 40 at% nitrogen.Theoretical estimates suggest that the majority of the incident excimer laser radiation is absorbed by the target with subsequent thermal transfer to the liquid producing a highpressure shock wave originating at the liquid-solid interface. Pressures up to 4.3 GPa are predicted with the expanding vapor layer reaching a terminal velocity after 5 μs and a total lifetime of 28 μs. Such a lifetime is considerably longer than the thermal pulse in the substrate (from a I-dimensional heat flow analysis). The results are discussed with reference to such estimates. Because the thermal diffusivity far exceeds that of the solute, the extent of nitridation is determined predominantly by the first 200 ns of the thermal pulse experienced by the target.
Physical and Chemical Sputtering at Very Low Ion Energy: the Importance of the Sputtering Threshold
Authors: Steinbruchel Christoph 
Published: March 2011

ABSTRACTA variety of data for physical etching (i.e. sputtering) and for ion-enhanced chemical etching of Si and SiO2 is analyzed in the very-low-ion-energy regime. Bombardment by inert ions alone, by reactive ions, and by inert ions in the presence of reactiveneutrals is considered. In all cases the etch yield follows a square root dependence on the ion energy all the way down to the threshold energy for etching. At the same time, the threshold energy has a non-negligible effect on the etch yield even at intermediate ion energies. The difference between physical and ion-enhanced chemical etch yields can be accounted for by a reduction in the average surface binding energy of the etch products and a corresponding reduction in the threshold energy for etching. These results suggest that, in general, the selectivity for ion-enhanced etch processes relative to physical sputtering can be increased significantly at low ion energy.
On the Use of MÖssbauer Nuclei as Probes of Radiation Induced Effects at Interfaces
Authors: Ingemarsson P. A. , Ericsson T. , Possnert G. , Wappling R. 
Published: March 2011

ABSTRACTConversion electron M6ssbauer spectroscopy was used as a means of investigating radiation induced changes at thin film interfaces. 25 Å thick layers of 57Fe were evaporated onto substrates of Si,SiO2 and A12O3 andcovered with 150 Å 56Fe. Samples were then subjected to ion irradiation with 20 MeV C14+ to doses ranging from 1012 to 2x 1014 ions/cm2 and subsequently annealed in vacuum at 450 ºC. Mössbauer spectra were recorded before and after each step. The analysis revealed chemical alterations, induced by the ion bombardment, indicative of film-substrate bond formation and reconstruction of residual surface hydrocarbons. The results are interpreted in view of accompanying enhancements in thin film adhesion.
Heavily Doped Ultra-Shallow Junctions Formed by an ArF Excimer Laser
Authors: Yoshioka S. , Wada J. , Saeki H. , Matsumoto S. 
Published: March 2011

ABSTRACTBoron doping of single crystal silicon using an argon fluoride excimer laser with diborane gas has been performed. Diborane gas has an absorption at 193nm, which leads to gas phase photodecomposition of the diborane. Utilizing the photolyic effect, we obtained high surface concentration and ultrashallow junctions of 5×1020 cm−3 and 0.1 µm, respectively. The photolytic effect enhances the incorporation of the dopant species.
Laser Patterning of High Temperature Superconducting Oxide Films
Authors: Gupta A. , Hussey B. W. , Jagannathan R. , Cooper E. I. , Giess E. A. 
Published: March 2011

ABSTRACTA focused argon ion laser (514 nm) beam has been used for patterning superconducting lines of YBa2Cu3O7–δ using films prepared from metal trifluoroacetate solution precursors. A stoichiometric mixture of the precursors is dissolved in methanol, and the solution is spun on yttria-stabilized zirconia substrate to form a film. The film is patterned by irradiating in selected areas by direct laser writing to convert the irradiated layers to an intermediate fluoride state, the nonirradiated areas being unchanged. The nonirradiated areas are then dissolved away, leaving a pattern of the fluoride material. This patterned layer is converted to the superconducting oxide in a subsequent high temperature step involving reaction with water vapor.
Photochemical Vapor Deposition of Aluminum Thin Films
Authors: Hanabusa Mitsugu , Oikawa Akira , Cai Peng Ying , Furuno Shigeo , Iguchi Satoshi 
Published: March 2011

ABSTRACTUsing dimethylaluminum hydride as the source gas and an ArF laser as the light source, aluminum thin films with low electrical conductivity were deposited via photochemical reactions. To emphasize surface reactions, vapor pressure was kept low with a t pical value of 6.7×10−3 Pa. The laser energy density was typically 23 mJ/cm2 per pulse. The deposition rate of aluminum films became reasonably high above a substrate temperature of 90 °C and increased thereafter with substrate temperature. The electrical resistivity was about four times greater than the bulk aluminum value. A strongly nonlinear dependence of the deposition rates on laser energy density was observed. The incremental change in thickness per pulse increased with the inverse of the pulse repetition rate, which indicated, together with area selectivity, the importance of surface photolysis of absorbed molecules.
Licvd of Cr(C,O) Films from Cr(CO)6 at 248 NM: Gas-Phase and Surface Processes
Authors: Nowak R. , Konstantinov L. , Hess P. 
Published: March 2011

ABSTRACTThe influence of laser fluence and carbon monoxide partial pressure on the deposition rate of thin Cr(C,O) films was investigated. The films were deposited from Cr(CO)6 mixtures with CO and Ar using a KrF excimer laser. The observed results are discussed with respect to the relative importance of gasphase and surface processes. The results reveal that under the present experimental conditions chromium atoms produced in the gas phase play only a minor role as direct film precursors in KrF laser-induced film deposition.
Laser Induced Temperature Rise In Semiconductors : Analytical Solutions, Application to the Transient
Authors: Maruani Alain , Nissim Y.I. , Bonnouvrier F. , Paquet D. 
Published: March 2011

ABSTRACTIt is shown how the systematic use of the method of integral transforms greatly simplifies the calculation of the temperature rises in laser irradiated media. In general, this method leads ultimately either to analytical results or to very simple numerical integrals (e.g. no poles, exponential kernels). We focus here on the analytical results, and discuss some aspects of CW laser heating, for large surface absorption, including radial dependance, depth dependance and transient nonlinearities. The new results derived in this treatment are in good agreement with experimental data from other studies.
Survey of the Thermodynamics and Kinetics of Crystallization of Si and Ge
Authors: Turnbull D. 
Published: March 2011

ABSTRACTThe thermodynamic interrelations of the crystalline (c-sc), amorphous semiconducting (a-sc) and liquid metal (lm) states of Si and Ge, based on the existing thermal data, are reviewed. Then the kinetics of the interfacial processes in the growth of c-sc and a-sc into undercooled lm and the conditions for transition from c-sc to a-sc growth are discussed.
Laser-Induced Surface Defects
Authors: Moison Jean-Marie , Bensoussan Marcel 
Published: March 2011

ABSTRACTThe influence of pulsed laser processing (PLP) on the structure and composition of Si, GaAs, Inp and au surfaces has been investigated as a function of the laser fluence. Above a threshold fluence, all initial structures turn into a (1×1) structure and the V-element content of the compound surfaces is decreased. The structure change is shown to be related to the existence of a number of atomic steps on the Plp surface (up to 10114 /cm2 equivalent broken bonds). These defects can be eliminated by further annealings. On the other hand, the stoechiometry defects, which are less numerous (1012−1013/cm2) cannot be eliminated. A model for the mechanisms of defect creation and annihilation during PLP is outlined. The incidence of PLP-induced defects on device technology is evaluated.