bluuebunny/crossref_metadata_2025_split huggingface dataset:
Properties of Ultrathin Amorphous Silicon Nitride Films on III V Semiconductors
Authors: Huang L.J. , Kwok R. W. M. , Lau W. M. , Tang H. T. , Lennard W. N. , Mitchell I. V. , Schultz Peter J. , Landheer D. 
Published: March 2011

ABSTRACTProperties of ultrathin (— lOnm) silicon nitride films on single crystal Si, InP and GaAs have been studied using Raman spectroscopy, medium energy ion scattering (MEIS), variable-energy positron annihilation spectroscopy and x-ray photoelectron spectroscopy (XPS). The silicon nitride films were prepared by remote microwave plasma chemical vapour deposition (RPCVD). The results showed that oxidation of the film due to air exposure was restricted to the near surface with an oxygen penetration depth no greater than 2 nm. The residual stress in the as-grown films was substrate-dependent. For films on Si (100), the film induced residual stress was compressive with a value of 0.5GPa. Annealing at 500°C for 60 minutes resulted in a complete release of the residual stress. Vacuum annealing at a temperature below 500° C also led to changes of the electrical properties in the films but not the substrate.
Advanced Dielectrics for Passivation of INSB
Authors: Barbour J. C. , Casalnuovo S. A. , Kurtz S. R. 
Published: March 2011

ABSTRACTA combination of Electron Cyclotron Resonance (ECR) plasma, electrochemical, and chemical growth process were examined to synthesize dielectric surface passivation layers on InSb. The material properties of ECR-grown SiOxNyon InSb at temperatures from 30°C to 250°C were investigated. Composition analysis was done using Rutherford backscattering spectrometry (RBS) and elastic recoil detection (ERD). The electrical quality of the passivation layer was characterized with capacitance-voltage (C-V) measurements on metal-insulator-semiconductor structures over the frequency range from 1 kHz to 1 MHz. Sulfided layers, Si3ON2on InSb, and sulfided layers capped with S3ON2all exhibited good C-V properties consistent with interface state densities on the order of 1011/cm2-eV, and flatband voltages of magnitude less than 1 V. The difference in adhesion of Si3N4on InSb and the adhesion of Si3ON2on InSb was described in terms of the strength of the bonding at the dielectric-InSb interface. This work is the first to demonstrate passivation of an InSb surface with high-quality ECR silicon oxynitrides grown at room temperature.
Features of Plasma Grown Native Oxides on Indium Phosphide
Authors: Belyakova E. D. , Belyakov S. V. , Berman L. S. , Gorelenok A. T. , Karimov I. N. , Karzhavin R. V. , Mikoushkin V. M. , Mokina I. A. , Sysoev S. E. , Shmidt N. M. 
Published: March 2011

ABSTRACTEllipsometry and XPS investigations of RF plasma grown native oxide and C-V measurements of its interface were performed.Strong dependence of the composition of the plasma grown native oxides and electric properties of MIS structures on the time of plasma treatment has been observed. The greater the content of stable polyphosphate phase of [InxPyOz] is in the native oxide composition, the better parameters of its interface with InP (NS 11 cm−2 eV−1 and the hysteresis of C-V characteristics≤0.2 V) and the lesser C-V drift after treatment may be achieved. Plasma oxidation results in creating a negative effective oxide charge density.
Electronic Structure of Defects in Amorphous Silicon Nitride
Authors: Robertson John 
Published: March 2011

ABSTRACTThe paper reviews the electronic properties of defects in amorphous silicon nitride (a-Si3N4) and the hydrogenated alloys a-SiNx:H. The main defects in a-Si3N4 are the Si and N dangling bonds (DBs). The Si DB forms a sp3 state near midgap, while the N DB forms a highly localized pπ level just above the valence band edge. The behaviour of the alloys changes near x ≈ 1.1, the percolation threshold of Si-Si bonds. In the Si-rich alloys, both band edges are Si-like, only Si DBs are seen and their density is controlled by equilibration with weak Si-Si bonds. The x>1.1 alloys behave like silicon nitride; the valence band changes towards N pπ-like, both Si and N DBs can arise, the Si DB can have a high density and prefers to be in its charged diamagnetic configurations.
Spectroscopic Investigations of the Ablation Plume of Several Inorganic Materials
Authors: Rosenfeld A. , Mitzner R. , Konig R. 
Published: March 2011

ABSTRACTTime resolved absorption spectroscopic investigations of the KrF laser ablation of MgO-ceramics and sapphire on atmospheric conditions were carried out with a time resolution of about 5 ns and a two-dimensional space resolution of less than 100 μm. The time delay between the ablation pulse and the broad band probe pulse was varied from 10 ns up to 10 μs.Absolute particle densities of the species were determined in dependence on the time delay and on the distance to the surface. The spatial and temporal behaviour of the particles in the ablation plume near the surface was found to be strongly affected both by air atmosphere and the reaction dynamic in the plasma zone. In the case of sapphire the time evolution of the densities of Al, Al+ and AlO species are discussed in comparison to measurements on vacuum conditions.
Mechanisms of Excimer Laser Ablation of Wide Band-Gap Materials: the Role of Defects in Single Crystal MgO
Authors: Dickinson J. T. , Jensen L. C. , Webb R. L. , Dawes M. L. , Langford S. C. 
Published: March 2011

ABSTRACTLaser ablation has important applications in surface modification, materials analysis, and thin film deposition. We have been examining the details of processes that lead to the emission and formation of particles (atomic/molecular ground state neutrals, excited neutrals, tions, electrons) when wide band gap materials are irradiated with pulsed UV laser light. Etching and deposition of wide bandgap materials is of particular interest due to their excellent insulating and optical properties. Our studies bear directly on achieving control of emission intensities and particle characteristics for use in film deposition and materials analysis. In model wide bandgap materials such as single crystal alkali halides and MgO (nominally transparent materials), exposure to repeated pulses of 248 nm excimer laser radiation of a few J/cm2 results in substantial interaction including extensive biaxial deformation and cleavage. Significant surface heating also occurs, consistent with strong free-carrier/laser interactions. We present strong evidence that achieving intense emission of atomic, molecular, and ionic particles actually depends on point defect production by laser-induced deformation and fracture. Defect production via dislocation motion yields orders of magnitude increases in laser vaporization of these wide bandgap materials, including cluster ion formation. The dependence of the laser-material interaction on dislocation density and mobility, as well as point defect density, suggests several novel strategies for the enhancing the ablative response or preventing laser damage.
Vacuum Ultraviolet Laser Ablation of Teflon (PTFE)
Authors: Herman Peter R. , Chen Boyi , Moore David J. 
Published: March 2011

ABSTRACTVacuum-ultraviolet laser ablation of Teflon is reviewed. The 157 nm irradiation of Teflon produces clean ablation sites well suited to micromachining applications in the electronics and medical fields. At 193 nm, etching profiles are poorly defined, showing swelling characteristics commonly produced by longer wavelength lasers. Comprehensive new 193 nm ablation data are presented showing the first evidence of incubation effects for Teflon. A computer model was developed to include ablation, swelling and incubation processes. The computer results satisfactorily model the experimental data over a large fluence range of 0.6 to 13 J/cm2 with three adjustable parameters.
Excimer Laser Induced Electrical Conductivity in Polymers
Authors: Phillips H. M. , Feurer T. , Callahan D. L. , Sauerbrey R. 
Published: March 2011

ABSTRACTThe electrical conductivity of high temperature polymers (i.e. polyimide) has been changedpermanently from 10−17 Ω−1 cm−1 to 10 Ω−1 cm−1 by excimer laser irradiation. The conduction mechanism is found to be phonon assisted variable range hopping between small (∼10 nm) carbon clusters that form a macroscopic percolation cluster. The critical concentration of carbon clusters is found to be Pc = 0.24 ± 0.02 and the critical exponent of the insulator-conductor transition is t = 1.97 ± 0.25.
Buffer Gas Effects on the Ablation Rates of Copper Using a Pico-Second Pulsed Nd:YAG Laser
Authors: Mao X.L. , Chan W.T. , Russo R.E. 
Published: March 2011

ABSTRACTCopper samples were ablated by a pico-second pulsed Nd:YAG laser in Ar and He gases under different pressures. At 1064 nm, the change of ablation rate of copper in He gas from lx10−5 to 760 torr is smaller than that in Ar gas. A model for the development of a plasma above the target surface is presented based on inverse Bremsstrahlung absorption between fast electrons and the gas medium. Ionization rate of the buffer gas versus pressure was estimated using the model, and a good correlation was found with the ablation rate.
Laser-Induced Surface Activation of Aluminum Oxide for Electroless Deposition
Authors: Pedraza A.J. , Godbole M.I. , Desilva M.J. , Lowndes D.H. 
Published: March 2011

ABSTRACTA new process for writing a copper pattern into alumina or sapphire substrates is presented. This process employs in sequence ultraviolet laser irradiation and electroless deposition of copper. The laser irradiation activates the substrate and copper is deposited in the activated region when the substrate is immersed in the electroless solution. The laser-activation can be performed months in advance to the deposition.A small amount of metallic aluminum is left on the surface of laser irradiated alumina substrates. The presence of this metallic aluminum appears to play a very important role in the laser surface activation process. In addition to aluminum cluster formation there must be other activation centers that promote copper deposition in laser treated alumina substrates. These catalytic centers are much weaker that the aluminum clusters and have been tentatively identified as surface defects.
Surface Modification of Aluminum Nitride and of Aluminum by Excimer Laser
Authors: Pedraza A.J. , Zhang J.-Y. , Esrom H. 
Published: March 2011

ABSTRACTA new technique for selective metallization of aluminum nitride (AIN) has been previously reported (1). It involves the use of an excimer laser to activate the AIN surface followed by electroless plating (Cu,Ni,Au) of the irradiated areas. The mechanism of decomposition of ALN is accompanied by ablation and the formation of an Al film on the substrate surface. Ablation rates are reported here as a function of fluence and number of pulses for three different wavelengths λ = 193 nm (ArF), λ = 248 (KrF) and λ = 351 nm (XeF).The effect of laser wavelength on the ablation rate is discussed. The ablation rates for Al were zlso measured and are compared with the AIN ablation rates. A numerical thermal model is used to analyze the mechanisms of laser ablation of both materials. The evaporation kinetics are incorporated into the model. The Clausius-Clapeyron approximation is used to make a self-consistent calculation of boiling and decomposition temperatures.
Pulsed Laser Deposition and Atomic Scale Characterization of Perovskite Oxide Films
Authors: Koinuma H. , Yoshimoto M. , Kawasaki M. , Ohkubo H. , Kanda N. , Gong J.P. 
Published: March 2011

ABSTRACTPerovskite oxide films inclusive of high Tc cuprates were fabricated by pulsedlaser deposition (PLD) under both conventional Po2(0.01∼1Torr) and high vacuum(≤10−6 Torr) conditions and their surface morphology, crystal quality, and conductivity were evaluated. Under optimized conventional PLD conditions, we obtained high quality YBa2Cu3O7−δ (YBCO) films that showed clear energy gaps and atomically flat surface image in the small area (4x4nm) STM/STS measurements. AFM and SEM ana!yscs on wider film surfaces (∼1x1μm), however, revealed granular structure of about 250nm grains with their root mean square roughness of 5nm.Under high vacuum PLD, i.e. laser MBE conditions, not only epitaxial but also two dimensional growth has been verified for such films as SrTiO3−x, SrVO3−y, and (AE)CuO2−z(AE=alkaline earth metal) by the RHEED observation of fine streak patterns and intensity oscillations. AFM demonstrated atomically flat surfaces of these films. Oxgen or nitric oxide pressure at the laser MBE growth gave crucial effects on the electrical conductivity of SrTiO3−x. and predominant crystal phase of SrCuO2−z.Insulating BaTiO3 films with atomically flat surfaces could be fabricated by both conventional and high vacuum PLD conditions. RBS channeling measurements revealed very high epitaxial quality (χmin−2%) of our SrTiO3 and BaTiO3 films. The factors controlling the surface morphology and electrical properties of perovskite oxide epitaxial films,are discussed.
Low Teperature Synthesis of Silicon Oxide and Oxynitride Films by Reactive Laser Ablation
Authors: Fogaassy E. , Fuchs C. , Slaoui A. , De unamumo S. , Stoquert J.-P. , Marine W. , Lans B. 
Published: March 2011

ABSTRACTSilicon oxide and oxynitride films are deposited, at low temperature (≤ 450°C) by pulsed ArF excimer laser ablation from silicon, silicon monoxide, fused silica and silicon nitride targets, performed under vacuum and in oxygen atmosphere. We investigate in this paper the specific influence of laser fluence, target materials, substrate temtperature and oxygen pressure on the composition and final properties of SiOxNy grown layers. The synthesis of good quality SiO2 films is demonstratedx. By contrast, the preparation of stoichiometric Si7N4 layers by laser ablation has to be optimized.
Vacuum Ultraviolet Spectroscopy Study of Excimer Lasergfenerated Plasmas: Spatial Distribution of Plasma
Authors: Chrise D.B. , Mehbnan G. , Horwit J.S. , Burkhalte P.G. , Newman D.A. , Leuchtner R.E. 
Published: March 2011

ABSTRACTEmission spectra from 1200 Å to 3500 Å have been measured for laser-generated plasmas produced by the focused output (1−4 J/cm2)of a Kr-F excimer.laser onto solid targets of single and multicomponent materials (e.g., Al, Y2O3, BaO, Cu, and YBa2Cu3O7−δ). We have measured the spatial distribution and fluence dependence of the plasma emission. The emission spectra indicated that very large density gradients from the large opacity at the target surface were present. In general, the spectra were dominated by excited neutrals and singly and doubly ionized species. Plasma emission spectra from Al have been analyzed in more detail to derive plasma temperature and density. A plasma temperature of 2 eV and an electronic density of ∼1018/cm3 at 2 J/cm2 was estimated from the relative line intensities. Spatial variation of the total vacuum ultraviolet emission provided evidence for laser absorptionin the ablated material.
Pulsed Laser Deposition of Thin Silicon Nitride Films
Authors: Xu Xiangqun , Seki Kanekazu , Chen Naiqun , Okabe Hideo , Frye Joan M. , Halpern Joshua B. 
Published: March 2011

ABSTRACTABSTRACTPulsed laser deposition of compressed Si3N4 powder has been used to grow thin SiNx films on a variety of substrates at substrate temperatures ranging from room temperature to 350°C. Film composition was analyzed by Auger electron spectroscopy. The SiN0.33 films have a band gap of 5.60 eV as measured by UV absorption. The FT-IR spectrum shows an absorption characteristic of Si-N. The Si/N ratio in the deposited films corresponding to various substrate temperatures has also been determined.
Preparation of PbTiO3-Pb(Mg0.5W0.5)O3 Thin Films Using Pulsed Laser Deposition
Authors: Lee B. W. , Lee H. M. , Cook L. P. , Schenck P. K. , Paul A. , Wong-ng W. , Chiang C. K. , Brody P. S. , Rod B. J. , Bennett K. W. 
Published: March 2011

ABSTRACTThepreparation of modified lead titanate (0.PbTiO3-Pb(Mg0.5W0.5)O3) thin films by pulsed excimer laser deposition on Pt-coated Si substrates has been studied. Films were prepared with substrate temperatures of 300–650°C, and ambient oxygen pressures of 2.7–4OPa. Phase formation and morphology of the films varied according to deposition conditions. At 650°C, 40Pa, well-crystallized perovskite single phase films were obtained. Most films were ferroelectric and showed preferred orientation which could be correlated with the texture of the underlying platinum. The effect of preferred orientation on the dielectric properties of the films is discussed.
Kinetics of Photodeposition of Superconducting Films
Authors: Chen C. H. , Phillips R. C. , Morrison P. W. 
Published: March 2011

ABSTRACTKinetics of photodeposition of superconducting films was studied by using real time in-situ monitoring of gas phase species with mass spectrometry and thin-film properties by Fourier Transform Infrared (FTIR) spectrometry. A mass spectrometer was used to study wavelength and power dependent desorbed atoms and molecules during laser ablation process. FTIR was used to monitor the surface properties of thin film. Real time surface temperatures can be easily obtained by FTIR. By combinging mass spectrometry and FTIR, an optimum condition of making high-quality superconducting film can possibly be found.
Photoluminescence Study of Reproduction of Energy Levels in Cdte Films Grown by Pulsed Laser Evaporation and Epitaxy
Authors: Wrobel J. M. , Moffitt C. E. , Dubowski J. J. 
Published: March 2011

ABSTRACTA comparison between the electronic energy structure of a target material and epitaxial films obtained from this material by pulsed laser evaporation and epitaxy is presented in the paper. Targets with various impurity concentrations were used in this experiment, and the epitaxial growth took place at various substrate temperatures. Studies of photoluminescence spectra included temperature and power dependencies of spectral features associated with the impurities. Properties of donor-acceptor pair recombination served for the analysis of the differences in the impurity concentration in the layers and the source material.
Epitaxial ZnS, ZnSe and ZnS-ZnSe Superlattices Grown on (001)GaAs By Pulsed-Laser Ablation
Authors: McCamy J. W. , Lowndes Douglas H. , Budai J. D. , Jellison G. E. , Hermant I. P. , Kimt S. 
Published: March 2011

ABSTRACTPulsed KrF (248nm) laser ablation of polycrystalline ZnS and ZnSe targets has been used to grow high quality, fully epitaxial ZnS and ZnSe thin films on (001) GaAs. Photoluminescence measurements of the ZnS thin films show strong edge emission, while ZnSe thin films show free excitonic as well as donor and acceptor peaks. By alternately ablating each target, strained layer superlattices of the form (ZnSe)m–(ZnS)n were grown with as many as 65 periods of compositional modulation. A ZnSxSe1–x structure also was fabricated which simultaneously incorporated both continuously graded and abrupt compositional changes.
Laser Ablation of CuInSe2 and CuIn/GaSe2 Alloys for Solar Cell Applications
Authors: hill Arthur E. , Leppåvuori Seppo , Tomlinson Robert D. , Pilkington Richard D. , Levoska Juhani , Ahmed Ejaz , Frantt Johannes 
Published: March 2011

ABSTRACTCopper indium diselenide (CIS) is one of the most promising materials proposed for use in the next generation of solar cells. A successful technique to deposit thin films of this material, which would maximise the advantage offered by its exceptionally high absorption coefficient and radiation resistance, has proved to be elusive. Dissociation of the source material during the physical deposition of these thin films has forced commercial production to adopt a binary (Cu/In) deposition route with a subsequent selenisation stage. This has proved to be a major difficulty; selenisation has introduced its own problems of non-uniformity and toxicity. Laser ablation is especially suited to the deposition of multi-component films in that the initial composition is conserved.Single crystal and polycrystalline targets of CIS were laser ablated using an XeCl excimer laser. The films were analysed using EDAX, XRD, RBS and Raman spectroscopy. Results from EDAX and RBS measurements indicated that the composition of the source material had largely been maintained in the films. This suggests that laser ablation could prove to be a significant technique in the preparation of complex ternary semiconductor thin films for solar cell applications which would allow the full potential of these materials to be realised in device production.
Preferentially Oriented Cubic Boron Nitride Films Grown on Si (001) Substrates by Ion Assisted Pulsed Laser Deposition
Authors: Ballal A. K. , Salamanca-riba L. , Doll G. L. , Taylor C. A. , Clarke R. 
Published: March 2011

ABSTRACTPreferentially oriented and extremely adherent cubic boron nitride films have been obtained using ion-assisted pulsed laser deposition on (001) Si substrates. The films were ∼ 1800 Å thick, optically transparent and formed an antireflective coating on the Si substrate. Infrared transmittance spectra showed a strong absorption peak at 1080 cm−1, indicating sp3 bonded film. Cross-sectional and plan-view transmission electron microscopy indicate that the cubic boron nitride films are polycrystalline having cubic zinc-blende crystal structure and a lattice constant of 3.62 Å. A preferred texture is observed with the [110] axis of cubic boron nitride parallel to [001] axis of silicon.
Deposition and Modification of Tantalum Carbide Coatings on Graphite by Laser Interactions
Authors: Veligdan James , Branch D. , Vanier P.E. , Barletta R.E. 
Published: March 2011

ABSTRACTGraphite surfaces can be hardened and protected from erosion by hydrogen at high temperatures by refractory metal carbide coatings, which are usually prepared by chemical vapor deposition (CVD) or chemical vapor reaction (CVR) methods. These techniques rely on heating the substrate to a temperature where a volatile metal halide decomposes and reacts with either a hydrocarbon gas or with carbon from the substrate. For CVR techniques, deposition temperatures must be in excess of 2000° C in order to achieve favorable deposition kinetics. In an effort to lower the bulk substrate deposition temperature, the use of laser interactions with both the substrate and the metal halide deposition gas has been employed. Initial testing involved the use of a CO2 laser to heat the surface of a graphite substrate and a KrF excimer laser to accomplish a photodecomposition of TaCI5 gas near the substrate. The results of preliminary experiments using these techniques are described.
Hydrodynamic Modeling of Laser Ablation
Authors: Mancini R.C. 
Published: March 2011

ABSTRACTWe present a hydrodynamic model to simulate laser ablation. The model conisistently takes into account the main physical phenomena involved in laser ablation: heating, thermal conduction, hydrodynamics and atomic kinetics. It computes the ionization balance, plasma formation and expansion, and the attenuation of the laser light as it travels through the plasma. Preliminary results are presented.
Stress Transients Generated by Excimer-Laser Irradiation of Polyimide
Authors: Zweig A. D. , Venugopalan V. , Deutsch T. F. 
Published: March 2011

ABSTRACTWe measure the stress transients resulting from pulsed excimer laser irradiation of polyimide at 351, 308, 248 and 193 nm, using thin (9 μm) piezoelectric PVDF (polyvinylidene fluoride) films. We find that fluences between 3·10−3 and 102 J/cm2 generate peak stresses between 104 and 109 Pa. Further, the results show three ranges of fluence where different physical mechanisms mediate the stress generation. In the lowest range of fluence, subsurface thermal decomposition (for λ = 351 and 308 nm) and photodecomposition (for λ = 248 and 193 nm) govern the generation of the observed stresses. At higher fluences we identify two regimes, independent of laser wavelength, where the gas dynamic expansion of the ablation products and plasma formation and expansion, are responsible for the generated stresses.