bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heteroepitaxial Growth of Cubic Boron Nitride on Silicon
Authors: Doll G. L. , Perry T. A. , Sell J. A. , TAYLORS C. A. , Clarke R. 
Published: March 2011

ABSTRACTNew x-ray diffraction measurements performed on bonm nitride films deposited by pulsed excimer laser deposition are presented. The x-ray data, taken with both a molybdenum rotating anode source and synchrotron radiation, indicate that the epitaxial cBN films are ≤ 200 Å thick. We also report the successful growth of oriented crystalline diamond on the (001) surface of cBN/Si substrates using the method of pulsed laser deposition. X-ray diffraction measurements indicate that the diamond layer is 200 Å thick with a lattice constant of 3.56 Å. The structures of metastable films (cBN and diamond) are very sensitive to growth conditions: we present evidence that an epitaxial-crystalline to incoherent phase transition occurs when the thickness of the films exceeds a critical value (∼ 200 Å for our present growth conditions).
Pulsed Excimer Laser Ablation Deposition of Boron Nitride on Si (100) Substrates
Authors: Friedmann T. A. , McCarty K. F. , Klaus E. J. , Boehme D. , Clift W. M. , Johnsen H. A. , Mills M. J. , Ottesen D. B. , Stulen R. H. 
Published: March 2011

ABSTRACTWe are studying the boron nitride system by using a pulsed excimer laser to ablate from hexagonal BN (hBN) targets to form cubic BN (cBN) films. We are depositing BN films on heated (600°C) silicon (100) surfaces in a flowing (0- 10 sccm) ambient background gas of either NH3 or N2 of varying partial pressure (0–100 m Torr). Infrared (IR) reflection spectroscopy indicates the films have short-range hexagonal order. Some films grown at low laser energy densities have shown the cubic phase in IR transmission. Auger electron spectroscopy (AES) indicates the films are nitrogen deficient, which is linked to changes in the target stoichiometry with increasing laser fluence. Raman spectroscopy on the films shows only a strong background luminescence suggesting a high concentration of defects associated with the nitrogen vacancies. Atomic force microscopy (AFM) of the films shows a surface morphology that roughens as the growth rate increases. In order to improve the film stoichiometry it was necessary to actively enhance the nitrogen content of the films. It was found that bombarding films during growth with ions from an ion gun filled with NH3 gas increased the N/B ratio but did not enhance the cubic phase. RF biasing the substrate gave films which showed both cubic and hexagonal features in IR reflection. High resolution transmission electron microscopy (TEM) confirms the presence of cBN grains of ∼ 200Å size in films grown with an RF bias.
Growth of Tetrahedral Phases of Boron Nitride thin Films by Reactive Sputtering
Authors: Moustakas T.D. , Lei T. , Molnar R. J. , Fountzoulas C. , Oles E.J. 
Published: March 2011

ABSTRACTTetrahedrally coordinated phases of boron nitride (c-BN and w-BN) were produced by reactive sputtering. The structure of the films was investigated by XRD and TEM diffraction, and found to be poly cry stalline. Films with microhardness up to 3500kg/mm2 were deposited but some degradation over time has been observed. A model for the stabilization of the tetrahedral phases over the graphitic one is proposed.
ESR Characteristics of Cubic Boron Nitride Crystals
Authors: Zhang Fangqing , Chen Guanghua 
Published: March 2011

ABSTRACTElectron spin resonance (ESR) spectrum have been used to study undoped cubic boron nitride crystals. The results show that the peak-to-peak width of the ESR signal is 27×10-4 T and the g-value is 2.00248, the spin density N s is 2.8×1015 cm-3, it is considered that the ESR signal is originated from the nitrogen dangling bond. Raman spectrum measurements have been also carried out, the peak positions are at 1054 cm-1 and 1306 cm-1.
An Investigation into the Use of a Diffusion Barrier in the Microwave Plasma Assisted Chemical Vapor Deposition of Diamond on Iron Based Substrates
Authors: Weiser Paul S. , Prawer S. , Hoffman A. , Manory R. , Paterson P. J. K. , Stuart S-A. 
Published: March 2011

ABSTRACTThe growth of CVD diamond onto iron based substrates is complicated by preferential soot formation and carbon diffusion into the substrate, leading to poor quality films and poor adhesion. One strategy to overcome these problems is the use of thin film barrier layers between the Fe substrate and the growing diamond film. The present investigation reports the growth of diamond films on Fe substrates coated with thin films of TiN. The effectiveness of the TiN layers in inhibiting C diffusion into the Fe substrate was investigated by Auger measurements of the C distribution within the TiN layer, through the interface and into the substrate both before and after diamond deposition.The results show that a layer of TiN only 250Å thick is sufficient to inhibit soot formation and C diffusion into the Fe bulk, as well as providing nucleation sites for CVD diamond growth.
High-Quality Amorphous Silicon Carbide Prepared by a New Fabrication Method for a Window P-Layer of Solar Cells
Authors: Ninomiya K. , Haku H. , Tarui H. , Nakamura N. , Tanaka M. , Wakisaka K. , Tsuda S. , Nishiwaki H. , Nakano S. , Kuwano Y. 
Published: March 2011

ABSTRACTA total area conversion efficiency of 11.1% has been achieved for a 1Ocm×1Ocm integrated-type single-junction a-Si solar cell submodule using a high-quality wide-bandgap p-layer doped with B(CH3)3 and other advanced techniques. This is the highest conversion efficiency ever reported for an a-Si solar cell with an area of 100cm2. As for a multi-junction solar cell, 12.1% was obtained for a 1cm2 cell with a high-quality wide-bandgap a-Si i-layer. The layer was fabricated by a hydrogen dilution method at a low substrate temperature for a front active layer of an a-Si/a-Si/a-SiGe stacked solar cell.For further improvement in conversion efficiency, a wider-bandgap a-SiC was developed using a novel plasma CVD method, called the CPM (Controlled Plasma Magnetron) method. From XPS and IR measurements, the resultant films were found to have high Si-C bond density and low Si-H bond density, p-type a-SiC was fabricated using the post-doping technique, and dark conductivity more than 10-5(Q. cm)-1 was obtained (Eopt3 ≥ 2eV; Eopt2 2.2eV), whereas that of conventional p-type a-SiC is less than 10-6(Ω·cm)-1. These properties are very promising for application to the p-layers of advanced a-Si solar cells.
Wide-Gap Polysilane Produced by Plasma-Enhanced CVD at Cryogenic Temperatures
Authors: Miyazaki S. , Shin H. , Okamoto K. , Hirose M. 
Published: March 2011

ABSTRACTPolysilane thin films have been grown by the rf glow discharge decomposition of SiH4 at substrate temperatures ranging from -84 to -110°C. The infrared absorption spectra have shown that polysilane chains (SiH2)n are predominantly incorporated in the matrix together with SiH3 which terminates the chain. Also, the infrared absorption band at 2120∼2140 cm-1 and a distinct Raman peak at ∼430 cm-1indicates that fairly long chains (SiH2)n with n>11 are produced. Polysilane prepared at -110°C has an optical bandgap of about 3.1 eV and exhibits a visible luminescence around 2.75 eV at 100 K.
Optically Induced Paramagnetism in Amorphous Hydrogenated Silicon Nitride Thin Films
Authors: Warren W. L. , Kanicki J. , Rong F. C. , Buchwald W. R. , Harmatz M. 
Published: March 2011

ABSTRACTThe creation mechanisms of Si and N dangling bond defect centers in amorphous hydrogenated silicon nitride thin films by ultra-violet (UV) illumination are investigated. The creation efficiency and density of Si centers in the N-rich films are independent of illumination temperature, strongly suggesting that the creation mechanism of the spins is electronic in nature, i.e., a charge transfer mechanism. However, our results suggest that the creation of the Si dangling bond in the Si-rich films are different. Last, we find that the creation of the N dangling-bond in N-rich films can be fit to a stretched exponential time dependence, which is characteristic of dispersive charge transport.
Selective Nucleation of Diamond Crystals on the Apex of Silicon Pyramids
Authors: Ramesham R. , Ellis C. 
Published: March 2011

ABSTRACTDiamond crystals have been selectively grown on the apex of anisotropically chemically etched silicon pyramids. A novel process sequence is developed which exposes patterned sharp apex of silicon pyramids surrounded by thermally grown silicon dioxide to a high pressure microwave plasma-assisted chemical vapor deposition (HPMACVD) process where the reactant feed gases are methane and hydrogen. Nucleation rate of diamond is very high on the sharp edge of a silicon mesa structure or an apex of a silicon pyramid as anticipated. Selective growth of diamond particles on the apex of silicon pyramids fabricated using various approaches were analyzed by scanning electron microscopy.
Observation of Gas Flow Patterns In A CVD Reactor For Wide Band Gap Semiconductor Thin Film Deposition
Authors: Atsumi Kinya , Ueno Yoshiki , Hattori Tadashi , Hamakawa Yoshihiro 
Published: March 2011

ABSTRACTA new method for the direct observation of two-dimensional gas flow patterns in a CVD reactor has been developed by combining a laser scanning technique with generating micron-sized TiO2 particles. With this specially developed technology, the size of generated TiO2 particles are quite uniform, and of high density by the use of hydrolysis of Ti-alkoxide in the ceramic honeycomb at the top inlet of the model chamber. In this system, vertical cross sections of the gas flow patterns can be visualized by illuminated TiO2 particles in a He-Ne laser light sheet. Using this technique, detailed gas flow patterns can be clearly identified in the reaction chamber. Changes in the gas flow patterns with the various growth conditions, such as gas flow rate and pressure, have been measured. In this presentation, GaAs thin film growth by the MOCVD method will be reported as an example.This gas flow visualization method could be a useful tool to identify the mechanism of CVD reactions to give better understanding about carrier gas transport and thin film growth for wide band gap semiconductors such as GaN, a-SiC, SiNx, etc.
Electronic Transition-Related Optical Absorption in Vanadia Films
Authors: Abuhadba Nada M. , Aita Carolyn R. 
Published: March 2011

ABSTRACTVanadium pentoxide (vanadia) is a wide band gap semiconductor. Its layered orthorhombic structure consists of alternating sublayers of V+O atoms and O atoms (vanadyl O) alone aligned perpendicular to the b-axis. This unique structure makes vanadia a useful host for alkali atom intercalation for electrochromic applications, and therefore, an understanding of its optical properties is important. Here, we study the optical absorption characteristics of vanadia in the incident photon energy range E=2.5–6.0 eV (λ=490–200 nm). The material is in the form of 0.1μm thick films sputter deposited in Ne/O2 discharges. Two types of films were studied: single-oriented films with the b-axis perpendicular to the substrate, and amorphous films with an oxygen deficiency. The optical absorption coefficient, α(E), was determined and interpreted in terms of the structure of the V 3d conduction band. Amorphous, O-deficient vanadia were examined for room temperature aging and were found to oxidize and increase in transmittance in the photon energy range studied.
ZnO on Si3N4 Bimorphs with Large Deflections
Authors: Choi Wai-Shing , Smits Jan G. 
Published: March 2011

ABSTRACTPiezoelectric bimorphs and piezoelectric strain sensors based on sputtered ZnO films were fabricated on Si3N4 cantilever beams to form tactile sensors. The sensors were used to determine object positions. Deflections of the bimorphs showed a quadratic dependence on the applied voltages. Deflection as large as 1166 μm were registered for a bimorph of 2980 μm long. The apparent d33 of ZnO under a bias of -4 volts was - 103 × 1O-12 m/V, which was approximately 20 times larger than the previously reported values of -5.12 × 10-12m/V. The large deflections of the bimorphs were due to the quadratic effect under strong electric field.
Nanometer Size Lead Iodide Particles
Authors: Mehrotra Vivek , Rodeghiero Eric , OTTO Jens W. , Giannelis Emmanuel P. 
Published: March 2011

ABSTRACTNanometer size lead iodide particles have been synthesized in the porous network of a cross-linked polymer matrix. The optical band gap of the nanocrystals is shifted towards higher energy as compared to the bulk value. This shift is attributed to the quantum size effect on excitons. Intercalation with aniline leads to a further shift in the band gap which depends on the dipole moment of the intercalated guest species. Differential scanning calorimetry and high temperature x-ray diffraction have been used to analyze the ferroelectric transition in Pbl2.
Diamond as a Material in Solid State Electronics
Authors: Vavilov Victor S. , Lebedev P.N. 
Published: March 2011

ABSTRACTPresent state of the work devoted to the control of properties of diamond is analyzed, with emphasis on the results obtained in USSR, including the data on ion implantation and several types of devices. Future possibilities of the work with single crystals, films and diamond ceramics are discussed and typical difficulties indicated.
Investigation of Cvd-Grown Diamond by Cathodoluminescence in TEM
Authors: Graham R.J. 
Published: March 2011

ABSTRACTHigh resolution cathodoluminescence (CL) spectroscopy and imaging have been performed in transmission electron microscopy (TEM) to analyze defects and impurities in polycrystalline diamond films grown by chemical vapor deposition (CVD) using a variety of gas mixtures, and oxyacetylene combustion flame synthesis (CFS). The combination of CL and TEM allows a direct correlation of film microstructure with the electronic structure due to defects. The CL was found to be very nonuniformly distributed on a submicron scale reflecting different spatial distributions of N, B and Si impurities and their correlations with microstructure. Band A CL due to closely-spaced donor-acceptor (D-A) pairs was correlated with dislocations in both CVD-grown and CFS material whereas band A from widely-separated D-A pairs was uniformly distributed in the films. CL from several different N-related point-type defects was observed and found to depend on the growth gases used, although no correlation with microstructure has been observed so far. A di-Si interstitial impurity, believed to arise from the Si substrate and reactor walls, was not correlated with any microstructure but varied greatly in concentration from grain to grain and from film to Film. In addition, both highly faulted and defect-free grains were found to emit no visible CL due to mid gap states.
Effect of Electrode Materials on the Microstructure of Sol-Gel Derived Pzt Ferroelectric Thin Films
Authors: Myers Sharon A. , Myers Edward R. 
Published: March 2011

AbstractA wide range of electrode materials have been investigated for use in ferroelectric-silicon CMOS technology. Numerous metal and metal-oxide films were deposited on silicon substrates and coated with sol-gel derived ferroelectric thin films. The films were sintered in either a diffusion furnace or by rapid thermal processing. Transmission electron microscopy was used to investigate the evolution of the resulting ferroelectric thin film microstructure and ferroelectric / electrode material interactions.Microstructural differences such as the volume fraction of the ferroelectric perovskite and pyrochlore phase, domains and grain structure are correlated with electrical results. A strong microstructural dependence on the substrate was found for the Cr, Zr, Hf and Ni electrode materials. In general, chromium and other metal-oxide films had high leakage currents and large volume fractions of the non-ferroelectric pyrochlore phase. Nickel electrodes displayed the best electrical results, but the microstructure is very different from the other ferroelectric films.
Crystallization of Sol Gel Pzt on Aluminium and Platinum Metallizations
Authors: Barrow D. , Vasant Kumar C.V.R. , Pascual R. , Sayer M. 
Published: March 2011

AbstractSol gel prepared PZT films from 0.3 - 1.0 μm in thickness can be crystallised at temperatures down to 520°C on aluminium substrates, but such films are often non-ferroelectric. Comparison with films made on Pt substrates suggests that reduced oxygen content at the interface nucleates a cubic non-ferroelectric PZT phase.
Analysis of Electric Fields, Space Charges, and Polarization of Thin-Film Ferroelectric Capacitors Based on Landau Theory
Authors: Brennan Ciaran J. 
Published: March 2011

AbstractThis paper describes a detailed physical analysis of the electric fields, space charges, and polarization of thin-film ferroelectric devices. The analysis is based on a previously developed model of the electric field dependent polarization, permittivity, and hysteresis of the thin-film polycrystalline ferroelectric, which was derived from the Landau-Devonshire theory. This paper includes the macroscopic effects related to device structure and composition, including potential barriers at contacts, domain relaxation, grain boundary surface charge, and interactions between the space charges and the non-linear polar displacement.
Microstructure and Electrical Properties of Very Thin Pzt Films Deposited byIn-SituIon Beam Sputtering.
Authors: Gifford Ken D. , Al-Shareef H.N. , Rou S.H. , Hren P.D. , Auciello O. , Kingon A.I. 
Published: March 2011

AbstractPZT films < 700Å have been synthesized by in-situ ion beam sputter deposition on Pt/Ti/MgO and RuO2/SiO2/Si substrates using deposition temperatures ≤ 500°C. Films on Pt/Ti/MgO had a highly preferred (001) orientation, whereas, the films on RuO2/SiO2/Si were randomly oriented. The formation of perovskite vs. pyrochlore phases has been studied. In the case of heavily Sn doped samples, it appeared that the doping promoted the nucleation of pyrochlore. We believe this effect was caused by a substantial reduction in the A:B cation ratio which was the result of Sn contaminated Pb targets. Electrical characterization was performed using parallel-plate electrodes. Hysteresis measurements showed high polarization values and coercive fields for the highly oriented films, whereas, the randomly oriented films showed much lower values of polarization. Fatigue measurements on the highly oriented films showed a sharp drop in polarization at 105or 106cycles. A decrease in Pr with time has been observed and is discussed.
Preparation and Microstructural Characterization of Ferroelectric Thin Film PbTiO3 on Si, MgO, and Sapphire Deposited by DC Reactive Multitarget Co-Sputtering.
Authors: Kim K.Y. , Hwang H.I. , Lee J.Y. , Choo W.K. 
Published: March 2011

AbstractPbTiO3 thin films on Si (100) plane were prepared by the DC reactive multitarget cosputtering technique. The film composition and structure were examined as a function of deposition parameters. The crystal structure and microstructure of PbTiO3 thin film deposited on Si at low substrate temperature of 200°C were examined as a fuction of post-annealing temperature by X-ray diffraction and transmission electron microscopy.The ferroelectric domain configurations were analyzed by plane-view TEM. The preferred orientation of PbTiO3 thin films deposited on MgO (100) and sapphire (1102) at high substrate temperature of 520°C were also examined.
Advances in Ferroelectric Thin Film Research at Nec and in Japan
Authors: Matsubara S. , Miyazaki S. , Sakuma T. , Miyasaka Y. 
Published: March 2011

AbstractHigh dielectric constant thin film capacitors for integrated circuits were fabricated with an LSI process. The capacitors comprized AI/TiN top electrode, Si3N4 interlayer insulator, SrTiO3 dielectric and Pt/barrier-metal/Si bottom electrode. Two types of capacitor structure were discussed on the basis of dielectric property and fabrication process. The TiN layer played an important role in suppressing degradation of insulating properties at elevated temperature, which was caused by a reaction between Al and SrTiO3. Breakdown strength larger than 6.6 MV/cm was obtained for 0.001 mm2 area capacitors. However, the strength decreased with increasing capacitor area. The area dependence may be due to surface defects which were introduced during the processes subsequent to SrTiO3 film deposition. The capacitance density of about 9 fF/μm2 was obtained for 150nm thick film. Recent activities of ferroelectric thin film research in Japan was given as well.
Residual Stress in Pzt Thin Films and its Effect on Ferroelectric Properties
Authors: Garino Terry J. , Harrington Mark 
Published: March 2011

AbstractThe residual stress in solution derived Pb(Zr.53Ti.47)o3, PZT 53:47, films was determined by measuring the bending of the substrate due to the stress. The substrate consisted of an oxidized (100) silicon wafer with 300 nm coating of platinum. In all cases the stress was tensile. Films fired at a temperature in the range where pyrochlore formation occurs (500° to 575°C) had the highest residual stresses, 200 to 350 MPa, whereas those fired at higher temperatures, 600° to 650°C, where the perovskite phase forms had stresses of 100 to 200 MPa. Stress measurements made during film firing indicate that the pyrochlore containing films had higher residual stress because their coefficient of thermal expansion was much larger than that of predominantly perovskite films. The effect of the amount of stress on ferroelectric properties was studied by making measurements on a film with and without the application of an external stress. The external stress was applied by bending a circular section of the substrate, which effectively lowered the amount of tensile stress in the film by ∼30%. Decreasing the stress in this manner was found to increase the remanent polarization by ∼11% and the dielectric constant by ∼2%.
Breakdown and Hysteresis in Thin Ferroelectric Polymer Films
Authors: Guy I. L , Tansley T. L. , Arafin P. , Moroney C. M. 
Published: March 2011

AbstractHysteresis loops obtained from sub-micron films of ferroelectric polymers show a maximum polarization which depends on the frequency of the driving field, the thickness of the film and the number of loops previously traversed (fatigue). We speculate that these effects result from changes in domain wall mobility. For films with thickness above 200nm, the hysteresis loops show no significant thickness dependence. This implies that the dimension of regions of field non-uniformity near the electrodes is less than 200 nm.In ferroelectric polymers subject to a uniformly increasing field, the variation of breakdown strength with the field ramp-rate indicates that sample heating has a significant effect on the dielectric strength. At low ramp rates (below 100 MVm−1s−1) the heating in the sample is mainly due to Joule heating and the dielectric strength increases with increased ramp rate. At higher ramp rates the predominant heating mechanism is dipolar dielectric loss and the dielectric strength decreases with increased ramp rate. The two mechanisms combine to produce a maximum in the dielectric strength vs ramp-rate plot.
Ferroelectric Thin Films for Microactuator Applications
Authors: Chen Jiayu , Udayakumar K. R. , Brooks Keith G. , Cross L. Eric. 
Published: March 2011

AbstractFerroelectric thin films of PZT and PMN-PT were fabricated by the solgel spin-on technique. The films show high dielectric constants, polarization and breakdown strength values. Using a laser interferometer (ultradilatometer), the piezoelectric and electrostrictive coefficients of the films were measured. The results indicate that the sol-gel derived ferroelectric thin films have good electromechanical properties and can be used in rnicroactuator applications.