bluuebunny/crossref_metadata_2025_split huggingface dataset:
Paramagnetic Defect Analysis in UV Lamp Induced Chemical Vapour Deposited a-SiO2 Films
Authors: Debauche C. , Licoppe C. , Flicstein J. , Devine R. A. B. 
Published: March 2011

ABSTRACTAn electron spin resonance study has been carried out on a-SiO2 films deposited from SiH4 and N2O gases using UV lamp induced chemical vapour deposition. Deposition pressures have been varied from 5 torr to 30 torr whilst the substrate temperature was maintained at 240°C. Bridging nitrogen (O3≡Si-N-Si≡O3) and oxygen-vacancy center defects are observed in small quantities (≈ 1016cm−3) whilst over coordinated N defects are observed in concentrations up to 1018 cm−3 dependent upon the deposition pressure. The concentration of these defects can be dramatically reduced either by depositing the a-SiO2 at high pressures (≈ 30 torr) or by post-deposition annealing at ≈ 600°C. Comparison with data on films produced by plasma enhanced chemical vapour deposition demonstrates that the mode of incorporation of nitrogen into the network depends critically upon the chemical species in the deposition reactor.
Charge Trapping Properties of Thin Plasma Nitrided Oxides Induced by Nitrogen and Hydrogen Incorporation
Authors: Plossu C. , Seigneur F. , Balland B. , Piot B. , Straboni A. 
Published: March 2011

ABSTRACTIn this work, we report the effects of an ammonia plasma nitridation on the charge trapping properties of thin SiO2 films in correlation with their nitrogen and hydrogen contents. Electron traps characteristics were determined by die avalanche injection technique. Hydrogen contents were measured by Elastic Recoil Detection analysis (ERDA). Nitrogen depth profiles were obtained with Auger spectroscopy. It is shown that the bulk electron trapping properties are essentially controlled by the specificity of hydrogen and nitrogen incorporation in the SiO2 films during the ammonia plasma process. For short nitridation times, an increase of hydrogen related electron trap densities is observed in good agreement with hydrogen ERDA measurements. However hydrogen concentration never exceeds 3 at% and can be scaled down by a short time post-nitridation anneal in oxygen, to a level comparable indeed inferior to that of a non-nitrided oxide. For heavy nitridation, an additional electron trap is detected which could be associated to the presence of nitrogen in the bulk of SiO2.
Energy-Filtered Electron Diffraction from Silica Thin Films
Authors: Qin L. C. , Hobbs L. W. 
Published: March 2011

ABSTRACTEnergy filtering has been applied to electron diffraction patterns to obtain electron scattering intensity data of single energy collected using a scanning transmission electron microscope. For amorphous materials, the technique permits reconstruction of radial distribution functions from elastically scattered electron intensity data; amorphous silica thin films have been analyzed in the present experiments. The radial distribution functions are characterized in terms of interatomic distances and are compared to neutron scattering results in the form of total correlation functions.
Plasma Deposited Oxynitride Films: Structural and Electrical Characterization
Authors: Scaglione S. , Mariucci L. , Mattacchini A. , Pecora A. , Fortunato G. 
Published: March 2011

ABSTRACTIn the present work structural and electrical properties of thin films, deposited by PECVD from He-diluted S1H4+NH3+N2O gas mixtures, have been studied. Film compositions have been analyzed by NRA, RBS and hydrogen content has been determinated by ERDA while Infrared spectroscopy has been used to evaluate the local bonding configurations. Electrical properties have been measured in metal-insulator-metal structures by I-V ramp. From the results obtained, the oxynitride films show suitable properties for application as gate insulator in amorphous silicon thin film transistor.
Accelerated Degradation Mechanisms in Amorphous Silicon Thin Film Transistors
Authors: Chung I. J. , Oh C. H. , Kim W. Y. , Hwang J. R. , Kim Y. S. , Park J. S. , Lee S. K. , Han M. K. 
Published: March 2011

ABSTRACTThe accelerated degradation phenomena in amorphous silicon thin film transistors due to both electrical stress and visible light illumination under the elevated temperature have been investigated systematically as a function of gate bias, light intensity, and stress time. It has been found that, in case of electrical stress, the threshold voltage shifts of a-Si TFT's may be attributed to the defect creation process at the early stage, while the charge trapping phenomena may be dominant when the illumination periods exceed about 2 hours. It has been also observed that the degradation in the device characteristics of a-Si TFT's is accelerated due to multiple stress effects, where the defect creation mechanism may be more responsible for the degradation rather than the charge trapping mechanism.
Low-Dielectric-Constant Interlayer Insulation for Multilevel Metallization
Authors: Maeda Masahiko 
Published: March 2011

ABSTRACTSiBN ternary and SiOBN quaternary films prepared by rf-plasma and/or ECR-plasma CVD have been proposed, and this paper evaluates the relationship between film structure and dielectric constant as well as the other film properties. The SiBN films contain Si-N and B-N bonds, and the dielectric constant of the SiBN films reduces with increasing proportion of B-N bonds in the films. The SiBN films are less hygroscopic than BN films and they are therefore more stable. For the SiOBN films, the effects of oxygen doping on the dielectric constant and on breakdown strength are discussed in terms of the film composition and bonding configuration. The dielectric constant decreases with increasing oxygen atomic ratio and reaches a minimum when the amount of oxygen is equal to the amount of silicon. The effectiveness of this low-dielectric-constant material as an interlay-er is confirmed in actual VLSIs with planarized two-level metallization using the SiBN interlayer.
Charge Trapping Centers in Ferroelectric Ceramics
Authors: Seager C. H. , Warren W. L. , Tuttle B. A. , Nasby R. D. , Dimos D. 
Published: March 2011

ABSTRACTElectron paramagnetic resonance (EPR), photo-thermal deflection spectroscopy (PDS), and electrical measurements have been used to characterize as-received and UV-lluminated lead lanthanum zirconate titanate (PLZT) and PZT ceramics. Following optical illumination we observe the activation of positively charged Pb+3 and negatively charged Ti+3 ions, as well as an increased broad absorption peak around 2.6 eV. The spatial distribution of the induced absorption correlates well with the location of the absorbed UV, suggesting that photo-produced carrier pairs are trapped at Ti+4 and Pb+2 producing the observed paramagnetism. The Ti+3 EPR spectra were successfully fit using the crystal field parameters derived from the PDS spectra. Preliminary results suggest that these charged paramagnetic ions can influence the electrical properties of PZT thin films. We investigated the effects of UV light and dc bias sequences by polarization-electric field (PE) measurements and find that the coercive fields are dependent on the sign of the applied bias during UV exposure. It is reasonable to expect that Pb+3 and/or Ti+3 ions act as the charge trapping sites which cause the threshold voltage shifts in the PE loop.
Physical and Electrical Properties of Tantalum Oxide Thin Films Deposited by Low Pressure Chemical Vapor Deposition
Authors: Hitchens William R. , Krusell Wilbur C. , Dobkin Daniel M. 
Published: March 2011

ABSTRACTTa2O5 films suitable for DRAM use have been deposited on silicon, polysilicon, and SiO2 by LP-CVD from Ta (OC2H5)5 and O2. Uniformity, reproducibility, and conformality are excellent. Annealed films are polycrystalline, and their surfaces are characterized by 2 nm high, 1 mgr;m diameter nucleation centers surrounded by circular crystallization fronts. The electrical properties of annealed films are dominated by a SiO2-rich layer which forms between the Ta2O5 and the silicon or polysilicon substrate.
Low Temperature Tantalum Pentoxide Thin Films
Authors: Kwon Kee-Won , Kang Chang-Seok , Park Tai-su , Sun Yong-Bin , Sandler Neal , Tribula Dana 
Published: March 2011

ABSTRACTTa2O5 films of high reliability and low leakage current density were obtained by low temperature deposition and subsequent high temperature oxygen anneal. At higher temperatures than 410°C, growth was governed by the formation of radicals in gas phase and oxidation on the surface, while at lower temperatures by the dissociation of reactant on the surface of substrates. As a result, the films deposited at lower temperatures had undensified structures, and contained more carbon that might be a leakage current source in Ta2O5 film. During post-deposition heat treatment in 800°C oxidating ambient, carbon was removed away and silicon was diffused from the substrate into the Ta2O5 film efficiently for its as-grown porous structure. After oxygen anneal, low temperature films get denser and are crystallized to mixed phase of orthorhombic and hexagonal Ta2O5, while high temperature films crystallized to orthorhombic single phase. Ta2O5 capacitor with low temperature films showed superior leakage characteristics applicable to sub-half micron memory devices.
Interactions in and Interfacial Structure of Annealed Co / a-Si3N4 Studied by Hrtem
Authors: Nguyen Tai D. , Nguyen Tue , Ho Herbert L. , Gronsky Ronald 
Published: March 2011

ABSTRACTInteractions between Co and a-Si3N4 films during Rapid Thermal Anneal (RTA) in N2 and Ar ambients, and during vacuum anneal, have been studied using plan-view and cross-sectional Transmission Electron Microscopy (TEM). Annealing in the temperature range 600–1000°C reveals agglomeration of the 12.5 nm Co layer and partial exposure of the nitride layer to the surface. Morphological damage of the Co/Si3N4 interface, and diffusion of Co into the nitride layer and possibly to the Si substrate, were observed after high temperature anneals. Phases of Co and CoSi2 were identified from the plan-view electron diffaction patterns. The Co/Si3N4 interaction seems to occur at lower temperature when annealed in vacuum. The microstructures and morphology of the layers and interfaces are presented. The mechanism for the diffusion of Co into the nitride layer is proposed.
Radiation Hardening of Simox Buried Oxide by Nitridation
Authors: Karulkar Pramod C. , Wyatt P. W. 
Published: March 2011

ABSTRACTRadiation hardening of SIMOX buried oxides by nitridation is demonstrated in this paper. Bare SIMOX oxide substrates, obtained by selective reactive ion etching of the top silicon film, were nitrided by annealing in ammonia at a high temperature. Al-Si thin film capacitors were fabricated on the SIMOX oxide and also on concurrently processed dry thermal oxides of similar thickness. Radiation hardness was tested by C-V measurements before and after the exposure to x-rays in an ARACOR x-ray source. SIMOX oxides were found to be inherently more resistant to radiation damage than the thermal oxides. Nitridation improved the radiation hardness of SIMOX oxides similarly to that of thermal oxides. Reoxidation nearly reversed the radiation hardening effect of nitridation in these thick (> 300 nm) oxides. For example, the following shifts in the flat band voltage were obtained when the capacitors were biased with ±5 V on the Al-Si dots and exposed to 100 krad (SiO2): -24 V for SIMOX oxide, -14.2 V for nitrided SIMOX oxide, and -22.8 V for reoxidized nitrided SIMOX oxide.
Influence of Hydrogen Plasma Treatment Upon Native Oxides Plasma Grown on INP
Authors: Belyakova E. D. , Belyakov S. V. , Berman L. S. , Gorelenok A. T. , Karimov I. N. , Karzhavin R. V. , Mokina I. A. , Shmidt N. M. 
Published: March 2011

Investigations of plasma grown native oxides on indium phosphide carried out recently [1,2] have shown that these oxides exhibit properties which are promising to be used in MIS structures on InP, due to their stable composition which includes [InxPyOz]n polyphosphate phase mainly and due to reduced density of interface states (Nss<1011 eV−1 cm−2). It has been shown also that MIS structures with plasma native oxides exhibit C-V characteristics shifted towards positive values of voltage bias. The flat band shift is assigned to a negative charge injected into oxide film during plasma oxidation. The presence of this negative charge in plasma grown native oxides on InP may cause instability of electric properties of MIS structures [2].The aim of this work was to make an attempt to influence upon negative effective oxide charge density by means of hydrogen plasma treatment.
Fast Photoluminescence Decay in a-SiNx:H Films
Authors: Palsule C. , Gangopadhyay S. , Yi S. , Shen J. M. , Naseem H. A. , Kizzar S. , Goh Freddy H. C. 
Published: March 2011

ABSTRACTWe have used a fast analog technique (100 ps resolution) to study photoluminescence (PL) decay in a-SiNx:H films in nanosecond (0.1–50 ns) range. Films prepared using RF glow discharge of NF3 and pure SiH4 were used for these measurements. The PL decays in the films were studied as a function of nitrogen content for 0≤x≤0.13. When the PL decay measured at 25 K is fitted with I (t) = ao +Σai exp (-t/Ti), where ao, ai and ti, are fitting parameters, we get three distinct lifetimes with t1 = 0.8 ± 0.2 ns, T2 = 3.5 ± 0.5 ns and T3 = 14.0 ± 3.0 ns. We find that these lifetimes do not change with nitrogen content but their relative contributions to the PL decay change with nitrogen content. We have also studied the effect of temperature and excitation energy on the PL decays at different emission energies. We suggest an excitonic origin to these three recombination processes.
Determination of Atomic Velocity Distributions Using Transient Absorption Measurements
Authors: Macler Michel , Fajardo Mario E. 
Published: March 2011

ABSTRACTResults of experiments on Al, Li, and Na atomic beams produced by laser ablation using XeCI excimer laser pulses (I∼107 to l08 W/cm2) are presented. Plume emission spectra showed that further than ∼5 mm from the targets most of the excited ablated species are in neutral, atomic form. Transient absorption measurements permitted the detection of ground state atoms with different flight times, at fixed distances from the target. The resulting time of flight (TOF) distributions were converted into velocity and kinetic energy (KE) distributions.The measured fluxes of fast atoms always increased with ablation laser intensity. The velocity distributions could not be fitted to Maxwell-Boltzmann (MB), or MB plus stream velocity type distributions. For Al plumes, comparison of velocity distributions measured at various distances from the target surface indicates that Al atoms are produced within ∼100 nsec following the leading edge of the ablation laser pulse, implying that there is a one-to-one mapping of the initial velocities to the distances traveled by the atoms after ∼1 μsec. This result should encourage efforts to develop a method of velocity selection of laser ablated metal atoms based on the spatial separation of the various velocity components along the direction of travel.
Collision Enhanced Decomposition of Microclusters Ablated from Si Surface by Excimer Laser Irradiation in Gas Environment
Authors: Kasuya A. , Nishina Y. 
Published: March 2011

ABSTRACTLaser vaporization processes in Si are analyzed in vacuum and in inert gas environment by space/time resolved optical spectrometry. The results show significant increases in the intensity of luminescence emitted from laser-vaporized plume in gas pressures up to 5 Torr in Ar and 20 Torr in Xe. The intensity then decreases with further increase in the pressure. The observed results are interpreted that collisions of inert gas atoms with a vaporized Si cluster enhances its fragmentation leading to ejection of electronically excited Si atoms and ions. The decomposition process of highly charged clusters are discussed in terms of electrostatic Coulomb effect.
Evolution and Dynamics of Excimer Laser Vaporized YBa2Cu3O7−δ
Authors: Dye R. C. , Brainard R. , Foltyn S. R. , Muenchausen R. E. , Wu X. D. , Nogar N. S. 
Published: March 2011

ABSTRACTPulsed laser deposition of thin films is a technology whose fundamental processes are often poorly understood. Because of the difficulty of monitoring in real time either the ablation process itself (the laser-solid interaction), or thin film growth (plume-substrate interaction), studies have largely relied on diagnostic studies of the ablated plume and the resulting film to infer details about other steps in the process. Information gained from this approach has helped improve the production of high-temperature superconducting thin films.We have studied plume dynamics during the in-situ pulsed laser deposition of YBa2Cu3O7−δ thin films. The 248 and 308 nm lines of an excimer laser were used to generate a plume from a bulk YBa2Cu3O7−δ target. Both fast intensified CCD imaging and spectral diagnostics were used to monitor plume dynamics. Variations in the plume distribution as a function of processing gas, pressure, fluence, energy, and spot size were monitored by film composition and spectral-and time-resolved imaging.
Ablation, Melting, and Smoothing of Polycrystalline Alumina by Pulsed Excimer Laser Radiation
Authors: Lowndes Douglas H. , Desilva M. , Godbole M. J. , Pedraza A. J. , Geohegan D. B. 
Published: March 2011

ABSTRACTThe effects of pulsed XeCl (308 nm) laser radiation on polycrystalline Al2O3 (alumina, 99.6% pure) and single-crystal Al2O3 (sapphire) are studied as a function of laser fluence. No laser etching ofeither material is detected below a threshold fluence value, which is much lower for alumina than for sapphire. Above this threshold, laser etching of both materials is observed following a number of incubation (induction) pulses. This number is much larger for sapphire than for alumina but decreases with increasing fluence for both materials. Laser etching rates for the two materials are similar at high fluences and after the incubation period. Scanning electron microscope images show that alumina melts and flows under repeated irradiation at fluences ≥0.7 J/cm2. Atomic force microscopy and surface profilometry reveal significant smoothing of the as-received polycrystalline alumina surface after repeated irradiations at moderate fluences (∼1−3 J/cm2). Ion probe measurements for alumina in vacuum confirm the incubation behavior, and reveal that at fixed fluence the (positive) charge collected per pulse saturates after a sufficient number of pulses, as does the etch-plume velocity. The results are interpreted in terms of laser-generation of a sufficient concentration of absorption centers before efficient ablation/etching of these wide bandgap materials can occur.
Laser Assisted Seeding for Electroless Plating on Insulators
Authors: Schrott A.G. , Braren B. , O'sullivan E.J.M. , Saraf R.F. 
Published: March 2011

ABSTRACTExcimer laser pulses with wavelengths of 248 and 308 nm were used to selectively seed Pd on SiO2 surfaces, making them suitable for electroless plating. This novel seeding process for insulating materials is accomplished with the sample immersed in the seeding solution, and occurs only on the areas of the substrate that are illuminated (through the liquid) by the laser light. The Pd content of the seeded samples increased with the number of pulses, but was rather independent of repetition rate. The deposition rate showed a dependence with wavelength consistent with a defect driven mechanism for electron excitation through the band gap of SiO2. These electrons then reduce the Pd ions in the solution in contact with the surface.
Direct Patterning of Quartz Substrates by Laser Ablation Using VUV Anti-Stokes Raman Pulses
Authors: Sugioka K. , Wada S. , Tashiro H. , Toyoda K. , Sakai T. , Takai H. , Moriwaki H. , Nakamura A. 
Published: March 2011

ABSTRACTHigh speed microfabrication of quartz substrates by laser ablation using vacuum ultraviolet (VUV) laser beams is described. The VUV light is generated by anti-Stokes stimulated Raman scattering of fourth harmonics of Q-switched Nd:YAG laser. The well-defined patterns with a cross-sectional profile of rectangular shape are formed by using a contact mask. The role of short wavelength components of the VUV laser beams in the process is discussed.
Fast-Iccd Photography and Gated Photon Counting Measurements of Blackbody Emission from Particulates Generated in The KrF-Laser Ablation of BN and YBCO
Authors: Geohegan David B. 
Published: March 2011

ABSTRACTFast intensified CCD photography and gated photon counting following KrF-laser irradiation of YBCO and BN targets reveal the first observations of very weak emission from slow-moving ejecta up to 2 cm from the target and times extending to ∼1.5 ms. Time-of-flight velocities inferred from the emission measurements indicate velocities (v ˜ (0.45−1.2) x 104 cm s−1) comparable to those measured for the large particles which often accompany the pulsed laser deposition process. Gated photon counting is employed to obtain temporally resolved spectra of this weak emission. The spectral shape is characteristic of blackbody emission, which shifts to longer wavelengths as the particles cool during flight in vacuum. Estimates of the temperature of the particles are made based on the emissivity of a perfect blackbody and range from 2200 K to 3200 K for both BN and YBCO when irradiated at Φ248 = 3.5 J cm−2 and 1.5 J cm−2, respectively. The temperature decrease of the particles in vacuum is compared to a radiative cooling model which gives estimates of the initial surface temperature and radii of the particles.
Epitaxial Growth of TiN on GaAs(100) by Pulsed Laser Deposition
Authors: Zheleva Tsvetanka S. , Jagannadham K. , Kumar A. , Narayan J. 
Published: March 2011

ABSTRACTEpitaxial growth of TiN films on GaAs(100) by pulsed laser deposition has been studied. Excimer KrF laser (λ=248 nm, τ=30 ns) has been used for deposition of TiN films in a chamber maintained at vacuum of ≤ 10−6 torr. The microstructure of TiN films has been characterized by x-ray diffraction and transmission electron microscopy (TEM). Cross-sectional high resolution TEM showed a smooth unreacted interface between the single crystalline TiN film and GaAs. The predominant epitaxial relationship was found to be [110]TiN//[010]GaAs, (220)TiN//(040)GaAs at a substrate temperature of 350°C. Modelling of epitaxial growth showed that the interfacial energy is an important term responsible for 45° rotation of the TiN unit cell with respect to that of GaAs. The high strain energy associated with the coherent epilayer is reduced by domain epitaxial growth. These films were characterized using high-resolution TEM techniques, and experimental results were rationalized by thin film growth modeling.
Structural and Electro-Optic Properties of Laser-Ablated Ferroelectric Bi4Ti3O12 Thin Films
Authors: Jo William , Cho Hag-Ju , Noh Tae Won , Cho Yun Seok , Kwun Suk-Il 
Published: March 2011

ABSTRACTFerroelectric Bi4Ti3O12 thin films have been deposited using second harmonics of a Q-switched Nd:YAG laser. Various single crystal substrates, including SrTiO3(100), SrTiO3(110). MgO(100), and MgO(110), were used. Structural and electro-optic properties of the films were investigated using XRD, x-ray pole figure, and linear birefringence measurements. It is found that substrate kinds and their surface orientations are important growth parameters which determine crystal axis orientation and electro-optic properties of the Bi4Ti3O12 thin films.