bluuebunny/crossref_metadata_2025_split huggingface dataset:
Performance of Polycrystalline Silicon Thin Film Transistors with Double Layer Gate Dielectric
Authors: Kung Ji-Ho , Hatalis Miltiadis K. , Kanicki Jerzy 
Published: March 2011

ABSTRACTThe electrical characteristics of n- and p-channel poly-Si thin film transistors having a double layer gate dielectric structure are reported. The gate dielectric consists of a silicon dioxide layer and a nitrogen-rich silicon nitride layer, both deposited by PECVD at low temperatures (≥400° C). When the silicon nitride was in contact with the poly-Si film, the effective carrier mobility (μeff), threshold voltage (Vth and subthreshold swing (St) for n-channel devices were 36 cm2/Vsec, -1.8 V and 1.65 V/decade, respectively, while for p-channel devices were 6 cm2/Vsec, -37 and 2.47 V/decade, respectively. These devices were not stable under negative gate bias stress, due to the injection of holes into the silicon nitride. When silicon dioxide was in contact with the poly-Si film, the μeff, Vth and St for n-channel devices were 26 cm2/Vsec, 3 V and 1.63 V/decade, respectively, while for p-channel devices were 10 cm2/Vsec, -22 V and 1.52 V/decade, respectively. These devices were stable under d.c. bias stress.
Eliipsometric Study of Rapid Thermal Annealed PECVD SiN Films
Authors: Alterovitz Samuel A. , Drotos Mark A. , Young Paul G. 
Published: March 2011

ABSTRACTA conventional parallel plate plasma enhanced chemical vapor deposition system using SiH4-NH3-N2 at 13.56MHz and 300°C was used to deposit SiN films on silicon substrates. Special care was used to assure an oxide free surface before deposition. The silane flow was varied to obtain stoichiometric Si3 N4 and silicon-rich films. Rapid thermal anneal (RTA) was performed for 30 sec at temperatures in the range 600°C — 900°C. Spectroscopic ellipsometry was used to characterize the films. Data was taken for 44 wavelengths (3200–7500Å range) at three angles of incidence on each sample. The structural and optical properties were obtained using several structural models of the film. The models assumed an effective medium approximation for the following three combinations of film constituents: Si3N4 and voids; Si3N4 and amorphous silicon (a-Si); Si3N4, voids and a-Si. In general, the three constituent model gave the best fits to the experimental data. In all films, we observed a decrease in the film thickness and void fraction as the RTA temperature increased. The a-Si percentage did not change vs. the RTA temperature. The reduction in void fraction for the silicon-rich samples was larger than for the Si3N4 film. The results are comparable to those measured by other methods on regular furnace annealed SiN films, i.e. annealing times of 30 minutes or more.
Sub-Nanometer-Equivalent PZT Thin Films Fabricated by Low-Temperature MOCVD
Authors: Miki Hiroshi , Ohji Yuzuru , Tachi Shinichi 
Published: March 2011

ABSTRACTFerroelectric PZT (Pb (Zr,Ti)O3) from 100 nm down to 50 nm thick was deposited on Pt/SiO2/Si substrates using MOCVD (Metal Organic Chemical Vapor Deposition) under reduced pressure at 550°C. Using Pb (DPM)2, Zr (DPM)4, and Ti(i–OC3H7)4 as precursors made it possible to control the composition of CVD films and to produce pure perovskite crystalline structure in the range of thickness less than 100 nm. Electrical measurements of the capacitors revealed that 50-nm PZT films typically had a dielectric constant of 500, resulting in the same capacitance as 0.4-nm SiO2.
Jet Vapor Deposition of Lead Zirconate Titanate (PZT) for Thin Film Pyroelectric Detectors
Authors: Golz John , Di Y. D. , Halpern B. , Schmitt J. J. , Cirino Phil , Bartlett A. 
Published: March 2011

ABSTRACTThin films of pyroelectric PZT deposited by Jet Vapor Deposition are considered here for application in IR detector arrays. PZT films of 0.5 μm thickness were deposited on platinum coated insulating substrates and then annealed to increase the perovskite grain size. Capacitor test structures were used to measure the dielectric constant, loss, AC resistivity, and pyroelectric coefficient. We compare the results with known values for bulk PZT and discuss their relevance to detector design and performance.
Localization and Electric-Field Modulated Electron Spin Resonance of a Shallow Donor in Simox
Authors: Vanheusden K. , Stesmans A. 
Published: March 2011

ABSTRACTLow temperature electron spin resonance (ESR) measurements were carried out on a broad range of separation by implantation of oxygen (SIMOX) substrates. The post-implantation forming anneal (T 1325°C) was observed to induce a donor in the SIMOX structure, more specifically, a shallow effective mass donor in Si of axial symmetry and preferential alignment along [001], likely an oxygen-related heat-treatment donor. Controlled etching back experiments revealed that the donor defects reside in an interfacial Si layer of at least 600$$A thick at both sides of the buried oxide layer reaching a local volume density of about 1018 cm−3. In the flat band situation, the donor was observed to be in a diamagnetic, ESR non-active state. Downward sweeping of the Si energy bands near the buried oxide interfaces, relative to the Fermi level, either by in situ positive ate biasing of large area metal-oxide-silicon capacitors fabricated on the buried oxide or γ7-irradiation induced positive charging of the buried oxide, was observed to alter the ionization state of part of the donors into an ESR-active state.
Sulfurized Passivation of GaAs (100) Surfaces
Authors: Li Z. S. , Hou X. Y. , Cai W. Z. , Wang W. , Zhang M. , Dong G. S. , Jin X. , Wang Xun 
Published: March 2011

ABSTRACTWe have developed a new electrochemical passivation method to obtain a quite stable sulfide layer on GaAs surface. This layer is very thick and contains a mixture of Ga, As, S, O and H compounds. The photoluminescence (PL) spectrum of such anodic sulfurized GaAs surface shows big intensity enhancement as compared with that of as-etched GaAs samples; No visual intensity decay occurs under laser beam illumination, which maintains for more than seven months. The structure and composition of the passivation layers are investigated by the X-ray photoelectron spectroscopy and the mechanism of the layer formation is suggested.
The Effect of UV Light on IR Absorption in Chemically Vapor Deposited a-SiNx:H Films
Authors: Seager C. H. , Kanicki J. 
Published: March 2011

ABSTRACTWe have measured the optical absorption properties of Plasma Enhanced Chemically Vapor Deposited (PECVD) films of hydrogenated amorphous silicon nitride (a-SiNx:H) over the energy range from 0.54 to 2 eV using Photothermal Deflection Spectroscopy (PDS). The near-infrared absorption properties of these films provide a quantitative estimate of the amount of H bonded to Si or N as well as a measure of the the density of electronic gap states due to species like Si dangling bonds. Typical PDS spectra obtained on as-deposited films show a broad absorption tail with a large number of narrow absorption peaks. Using the phase sensitive feature of this spectroscopy we are able to separate nitride-related absorption from that arising from the fused quartz substrates. In addition to the broad, featureless band tail, whose magnitude is quite sensitive to optical excitation with light above ̃3.9 eV, we observe a number of narrow absorption peaks which we identify as overtones of localized vibrational modes. Specifically, we see peaks at 0.82 and 1.20 eV which we identify as the 1st and second harmonics of N-H stretching vibrations, and several other peaks whose origins remain undetermined. Prolonged UV excitation produces no detectable change in these vibrational modes, although large changes are seen in the underlying absorption tail. This reinforces previous suggestions that photoinduced changes in these films do not arise from rearrangement of the bonded hydrogen.
Dangling Bonds in Amorphous Silicon Nitride Alloys: Predictions of the Free Energy Model
Authors: Smith F. W. , Efstathiadis H. , Yin Z. 
Published: March 2011

ABSTRACTThe free energy model (FEM) for bonding in a-SixNyHz alloys has been extended to include the contributions of neutral and charged Si and N defects to the free energy of mixing of the amorphous alloy. The FEM predicts that the dominant defects in N-rich alloys are N2o, N2-, and either S3+ or N2+, in contrast to the results of experimental studies that find the dominant neutral, paramagnetic defect to be Si3o. It is concluded that either the observed Si3o defects are not in thermodynamic equilibrium with the amorphous network or the N2o defects have energy levels which lie much higher in the energy gap than currently believed.
Measurements and Simulations of Temperatures in Polyimide During Excimer Laser Ablation
Authors: Brunco D. P. , Thompson Michael O. , Otis C. E. , Goodwint P. M. 
Published: March 2011

ABSTRACTThe temperature at the interface between a thin polyimide film and a quartz substrate was monitored as a function of time during KrF (248 nm) laser-induced heating and ablation using thin film NiSi thermistors. These experimental temperature measurements were coupled with heat flow simulations to obtain time-resolved temperature profiles in the polyimide. Thermal properties of the polyimide were estimated by requiring that the simulations reproduce experimental temperature profiles. The peak surface temperature in the polyimide at the onset of ablation was subsequently estimated from these simulations, producing a value of 1660 ± 100 K at the observed ablation threshold fluence of 36 mJ/cm2. Simulations were also used to explore the role of pulse duration on polyimide ablation.
Deposition of Thin Film SrFeO2.5+x by Pulsed Laser Ablation
Authors: Sanders Brian W. , Post Michael L. 
Published: March 2011

ABSTRACTPulsed laser ablation has been used to deposit thin perovskite films based on the formula: SrFeO2.5+x (x = 0 to ≈ 0.5). Good quality films have been deposited on (1102) and AT cut quartz substrates at temperatures ranging from 300 to 1130 K. Films grown below 770 K showed little or no preferential crystallinity. Temperatures around 913 K produced films predominantly oriented (200), while temperatures greater than 1000 K produced films with (110) orientation. Films were grown from pellets of two compositions (SrFeO2.5, and SrFeO≈3). The former had a higher ablation threshold than the latter. The atmosphere during cooling had a greater effect on the film's oxygen content than the growth atmosphere. Films cooled in vacuum had the brownmillerite structure (x=0), whereas films cooled in 53.3 kPa oxygen had the cubic perovskite structure (x≈0.5).
Microanalysis of Calcium-Aluminosilicate Glass Films Grown on α-Al2O3 by Pulsed-Laser Ablation
Authors: Mallamaci Michael P. , Bentley James , Carter C. Barry 
Published: March 2011

ABSTRACTPulsed-laser ablation has been used to deposit amorphous calcium-aluminosilicate films on α-Al2O3 single-crystal substrates. The microstructure and composition of each glass film was characterized using analytical electron microscopy (AEM). Composition was dependent on substrate temperature during deposition and thickness of the deposited glass layer.
Laser Ablation Deposition of Germanium Oxide Thin Films
Authors: Wolf Paul J. , Christensen Thomas M. , Coit Nathan G. , Swinford Richard W. 
Published: March 2011

ABSTRACTLaser pulsed sputtering of GeO2 targets in both vacuum and oxygen environments is us;ed to produce germanium oxide thin films. Infrared transmission and Auger electron spectroscopies are employed to infer compositional information on the films. The films grown in vacuum are oxygen deficient and they show a radial variation in the metal to oxide content. In contrast, the films grown in an oxygen atmosphere appear stoichiometric along the entire film.
Growth of ZnSe Epitaxial Layers and ZnSe/ZnS Superlattices by Pulsed Laser Deposition
Authors: Rajakarunanayake Y. , Luo Y. , Adkins B. T. , Compaan A. 
Published: March 2011

ABSTRACTWe report the successful growth of ZnSe and ZnSe/ZnS superlattices on GaAs by pulsed laser deposition. An XeCl excimer laser operated at 308 nm was used to ablate/evaporate Il-VI bulk targets in an ultra high vacuum enclosure. For typical growth temperatures in the range 350°–450°C we obtained epitaxial layers with excellent optical properties. The laser power and fluence were varied to produce growth rates in the range 0.1–1 Å/pulse. The photoluminescence of the pulsed laser deposited ZnSe layers showed dominant bound and free exciton features. The superlattice samples showed large blue shifts (∼400 meV) in the photoluminescence as the layer thicknesses were varied. These results are consistent with strong quantum confinement of the heavy holes in the ZnSe layers (valence band offset for ZnSe/ZnS ∼ 850±100 meV), while the electrons are not confined to either layer because of very small conduction band offsets Strong exciton photoluminescence exhibited by our samples indicates that pulsed laser deposition is a promising growth technique for the fabrication of iI-VI epitaxial layers and strained layer superlattices for visible light emitter applications.
Laser Processing, Characterization, and Modeling of Epitaxial Si/TiN/Si (100) Heterostructures
Authors: Chowdhury Rina , Chen X. , Jagannadham K. , Narayan J. 
Published: March 2011

ABSTRACTWe have successfully deposited multilayer Si/ITiN/Si(100) epitaxial heterostructures at a substrate temperature of 600°C in a chamber maintained at a vacuum of ∼10−7 torr using pulsed laser (KrF: λ = 248 nm, τ = 25 ns) deposition. This silicon-on-conductor device configuration has potential applications in three-dimensional integrated circuits and radiation hard devices.The two interfaces were quite sharp without any indication of interfacial reaction between them. The epitaxial relationship was found to be <100> Si II<100> TiN II<100> Si. In the plane, four unit cells of TiN matched with three unit cells of silicon with less than 4.0% misfit. This domain matching epitaxy provides the mechanism of epitaxial growth in systems with large lattice mismatch. Energetics and growth characteristics of such domain matching epitaxy in the high lattice mismatch Si/TiN/Si(100) system and possible device implications are discussed.
Amorphic Diamond Films Produced by Laser Ablation
Authors: Collins C. B. , Davanloo F. , Lee T. J. , You J. H. , Park H. 
Published: March 2011

ABSTRACTFour types of diamond films have been shown to be stable and free from hydrogen: crystalline diamond, amorphic diamond, i-C and defected graphite. Each is significantly harder than other forms of carbon, but only now are quantitative values of hardness being reported. In this work nanoindentation techniques were used on these highly elastic films and linear ranges of plastic response were identified. Values of hardness were extracted from the on-load data for amorphic diamond and crystalline diamond that could not be distinguished from the hardness of naturally occurring diamond. This seems to explain why thin layers of amorphic diamond have been so effective in protecting substrates from the erosive impacts of particles and droplets reported in previous studies.
Cage Breaking Threshold in DLPD of C60
Authors: Hascicek Yusuf S. , Kleinhammes Alfred , Testardi Louis R. 
Published: March 2011

ABSTRACTThin film patterns of desired shape or configuration made of about 15 μm - lines were directly written from a disk of C60 by employing a new laser technique called direct laser patterned deposition (DLPD). DLPD is an ambient technique, needing no special environment or material preparation. Since the ablation and deposition are very localized and deposition and patterning are done in one step this is a very cost efficient process. An energy density threshold was found. Above this density resistance of DLPD films dropped sharply indicating that the C60 cage was broken at least in part of the film.
X-Ray Photoelectron Spectroscopy of Polytetrafluoroethylene Thin Films Grown by Pulsed Laser Deposition
Authors: Shah S. Ismat , Blanchet Graciela B. 
Published: March 2011

ABSTRACTPolytetrafluoroethylene (PTFE) films were prepared by laser ablation of bulk PTFE targets using a Nd-YAG laser (4th. harmonic). Both low and high molecular weight PTFE targets were used. X-ray Photoelectron Spectroscopy of the deposited films indicates that under certain deposition conditions it is possible to transfer the material of correct composition from the target onto the substrate. Films ablated with lower laser fluence were fluorine deficient. Fluorine deficiency leads to the formation of CF, CHF, and crosslinked carbon impurities. The background gas in the deposition chamber does not seem to have much effect on the composition. Films deposited with either Ar or CF4 as the background gas have similar compositions. The oxygen concentration of the films decreases with the increase in the laser fluence. At the highest fluence used, 1.5 J/cm2, the O concentration was less than 1% regardless of the molecular weight of the target material.
Molecular-Dynamics Simulations of Laser-Ablation and Ionassisted Thin Film Deposition
Authors: Feil H. , Kools J.S.C. , Dieleman J. 
Published: March 2011

ABSTRACTMolecular dynamics simulations are performed of Cu thin film growth on Cu (111). Ion-Assisted Deposition is simulated by bombarding the substrate with Cu+ ions with a kinetic energy of 80 eV, while 1 eV Cu atoms are used for the simulation of Laser Ablation Deposition. It appears that Ion-Assisted Deposition leads to sputtering, enhanced surface mobility, surface disorder, mixing and rather deep damage. This is discussed in some detail. Laser Ablation Deposition, using laser fluences just above the ablation threshold, does not lead to damage and mixing. Sharper interfaces and more perfect heterostructures and superlattices can be produced using Laser Ablation Deposition.
Imaging and Characterization of Plasma Plumes Produced During Laser Ablation of Zirconium Carbide
Authors: Butt Darryl P. , Wantuck Paul J. 
Published: March 2011

ABSTRACTLaser diagnostic methods are developed and used to characterize the behavior of laser ablated zirconium carbide (ZrC). Emission from zirconium atoms dominates the total emission of the plasma plumes, which are estimated to have excitation temperatures of 9000 to 12,000 K under the conditions studied. Emission from species such as C, C2, and C3 were absent from the spectra due to the inherently low emission intensities of these species compared with that of Zr. Using a CCD camera, images of the plasma plumes are obtained from the emission and through the use of planar laser induced fluorescence of zirconium atoms.
Thermal Properties of Nanocrystalline Silver
Authors: Wu Xijun , Zhang Hongfei , Qin Xiaoying , Chen Lifang , Wang Guanzhong , Fang Rongchuan 
Published: March 2011

ABSTRACTThe thermal properties of the nanocrystalline metal Ag (n-Ag), with the average grain size of 10 run, synthesized by an inert gas condensation and in situ compacting technique under different pressures of 0.2 to 1.5 GPa were studied. The thermal stable temperature for asprepared state is 373K, above which the grain growth appears at different rates. An exothermal peak and an endothermal peak occur on the DSC curves of the n-Ag. The enthalpy of both peaks are dependent upon the compacting pressure. Tht enhancement of the specific heat in going from the polycrystalline to the nanocrystalline state varies between 5.4% and 3.6% in the temperature range of 380K to 540K. The thermal diffusivity at room temperature increases with grain growth, and approaches to the corresponding value of the polycrystalline Ag.
Processing of Chromium Silicide-Silicon Carbide Nanostructured Composite by Thermal Conversion of Spray Dried Precursor Powders
Authors: Luo Ping , Strutt P. I. 
Published: March 2011

ABSTRACTA new group of nanostructured composites with chromium silicide and silicon carbide has been developed. These composite powders which are about 20-40 rm in size were prepared by the chemical synthesis route and were characterized by UV, DTA/TGA, XRD, FTIR and SEM. Chemical reaction and phase formation versus the processing temperatures have been investigated and discussed. The particle size and the lattice parameter of the synthesized composite have been found to be dependent on the processing temperatures. A possible reaction mechanism of the nanostructured silicon oxide to silicon carbide is proposed.
Preparation and Characterization of Y3Al5O12 (YAG) from An Alkoxide-Derived Polymer
Authors: Jiang Zhiping , Rhine Wendell E. 
Published: March 2011

ABSTRACTThe controlled hydrolysis of Al(O-sec-Bu)3 and Y(O-iso-Pr)3 or the reaction of Y(OOCCH)3 with partially hydrolyzed Al(O-sec-Bu)3 [AlO0.75(O-sec-Bu)1.5] resulted in the formation of soluble polymeric materials. Pyrolysis of these materials under a flow of oxygen led to the formation of yttrium aluminum garnet (YAG) at 650-1500°C. YAG was the only crystalline phase observed during pyrolysis, and the Al/Y ratio of the pyrolysis products and the starting material was identical. However, infrared spectroscopy indicated that carbonate groups and entrained CO2 existed in the products at temperatures up to 1250°C. The pyrolysis chemistry of the precursors and the microstructure of the products were studied by FT-IR, TGA, XRD, SEM and elemental analyses.
Nanograin-Boundary-Controlled Reordering in Mechanically Disordered Nanocrystalline L12-Type Ni3 Al+Fe
Authors: Yavari A.R. 
Published: March 2011

ABSTRACTUsing mechanical attrition (milling) which also transforms the material into nanocrystalline form, various L12 or γ-type Ni3 A1-Fe alloys have been prepared in metastable-γ form and their magnetisations M(γ) and M(γ) and Curie temperatures Tc(γ) and Tc(γ) measured.Using magnetic properties we determine isothermal ordering kinetics in the nanocrystalline γstate and find that the ordering reaction cannot propagate across the nanograin boundaries. Each grain must obtain its own γ nucleus thus resulting in a Johnnson-Mehl-Avrami exponent n =1.
Characteristics of Cordierite-ZrO2 Composites Fabricated by The Multiphasic Sol-Gel Route
Authors: Jang Hyun M. , Lim Byung C. 
Published: March 2011

ABSTRACTBased on the electrokinetic properties of aqueous silica, boehmite, and ZrO2 dispersions, cordierite-ZrO2 composites were fabricated by the multiphasic sol-gel (or nanometer-scale sol mixing) route. The average particle sizes of boehmite and ZrO2 used in this study are 70 nm and 40 nm, respectively. The fabricated composites were characterized by a dense and homogeneous microstructure and by a uniform spatial distribution of submicron-sized tetragonal ZrO2 particles (200 nm) throughout the matrix. The microstructure of the matrix was represented by small-sized grains (< 400 nm) with a highly uniform grain-size distribution. The enhanced fracture toughness with increasing ZrO2 content was partly attributed to the martensitic t → m transformation. The formation of detrimental zircon (ZrSiO4) was avoided by suitably adjusting the heating schedule during sintering.
Hard Coatings for Polymer Films by Biomimetic in situ Precipitation
Authors: Lombardi John L , Calvert Paul 
Published: March 2011

ABSTRACTHard siliceous coatings on polyethyleneterephthalate (PET) surfaces have been prepared upon hydrolyzing a tetraisocyanatosilane permeant present in biaxially oriented PET film samples. The structure of these films differs from commercial PET film materials in that silica is present both as a surface layer and as discrete submicron particles dispersed throughout the films. In order to accomplish this, it was found that suitable silica precursors should be chemically compatible with the polymer and have calculated Hildebrand solubility parameter values similar to that for PET.