bluuebunny/crossref_metadata_2025_split huggingface dataset:
Processable Thiophene Copolymer With A Chiral Amino Acid Side Chain
Authors: Balasubramanian Srinivasan , Chittibabu Kethinni G. , Kumar Jayant , Tripathy Sukant K. 
Published: April 2011

ABSTRACTConjugated polymers in general, and polythiophenes in particular have been attracting attention in the field of molecular electronics. Polythiophenes functionalized at the β- position with various groups have resulted in processable, conjugated polymeric systems with applications such as organic electrodes, photorefractive materials, electro-luminescent devices, among others. We report the synthesis of a thiophene copolymer with alkyl and chiral amino acid substituents at the β- position. We have synthesized a solution processable poly[3-octylthiophene-co-(N-1-carboxyl, 2- (4-hydroxy-3-nitrophenyl)ethyl)-3-thiophene acetamide] with 3-nitro-L-Tyrosine as the chiral amino acid side chain. The UV-Visible and optical rotatory dispersion spectra of the new copolymer are discussed.
Multilayer Structures and Emissive Regions in Organic Thin-Film Electroluminescent Diodes
Authors: Aminaka E. , Tsutsui T. 
Published: April 2011

ABSTRACTThe relationships between emission quantum efficiency and emissive regions in organic thin-film electroluminescent (EL) devices were studied. As an emissive layer (EML) and an electron transport layer (ETL) material, 9, 10-bis(4-diphenylaminostyryl)anthracene and 1,3- bis(4-tert-butylphenyl-1,3,4-oxadiazolyl)phenylene, respectively, were used. A zone doped with 2,4-bis(4-diethylamino-2-hydroxyphenyl)-1,3-dihydroxycycrobutenediylium dihydroxide was formed in an EML. The relationships between the emission intensities from the dopant and the positions of doped zones gave information on the emissive regions in each EL device. The emissive region in the single-layer (SL) device consisting only of an EML extended over the EML. That in the two-layer device (DL-E) in which an EML was combined with an ETL was located within 10 nm-wide region near the EML/ETL boundary. Moreover, the emission efficiency of the DL-E device was found to be about 20 times as high as that of the SL device. Therefore, it was found that the carrier recombination within the narrow region sufficiently apart from electrodes gave high emission efficiency.
Reproducible growth of Highly Oriented (OO1) YSZ Films on Amorphous AiO2 Substrates by MOCVD
Authors: Doubinina G. , Stauf G. T. 
Published: April 2011

ABSTRACTThe possibility of growing crystallographically aligned films of good quality on polycrystalline or amorphous substrates is of great interest, both for fundamental understanding of film growth mechanisms, and for potential applications such as buffer layers for silicon-on-insulator devices and an epitaxial transition layer for cuprate superconductor thin films grown on substrates with large misfits. Deposition conditions for yttria-stabilized zirconia (YSZ) thin films were investigated and optimized, and highly (001) oriented YSZ films were reproducibly prepared on amorphous substrates by MOCVD. We believe that the formation of a highly oriented crystalline film on an amorphous substrate can be interpreted in terms of the inherent features of MOCVD process, and a working model of this process is suggested.
Advanced Interactive Personal Computer-Based Process Control Systems for Oxide MOCVD Systems.
Authors: Tompa G.S. , Shen D. , Zhang C. , Murzin I.H. 
Published: April 2011

ABSTRACTA versatile control system, which uses standard commercial software and hardware has been developed and applied to control oxide (and carbide) MOCVD and CVD systems. The control system is implemented within a personal computer platform. The system operates in the real time Microsoft WindowsTM environment utilizing the full advantage of the sophisticated graphical user interfaces, dynamic data exchange, networking, and multitasking capabilities. We have used two different sets of commercial software to control and monitor system hardware. The first software set is INTOUCHTM, a Man-Machine interface software from WONDERWARETM in conjunction with Microsoft ExcelTM and I/O interface software. The second software set is LABVIEWTM, which is primarily a data acquisition control system from National Instruments, combined with Visual BasicTM. Both systems include a friendly interactive real-time windows-based user interface, an advanced process entry and recording spread sheet interface, alarm and security management systems, data display and recording, maintenance routines, and complete networking and remote operation capabilities. In addition, the configurations provide a flexible hardware interface that can directly interface to I/O cards in the PC's bus, as well as to most industrial Programmable Logic Controllers, various types of process controllers, I/O devices and other forms of hardware. Most importantly, the system can interface with any in-situ process monitor or higher level intelligent process control systems in order to optimize the process. Modules may be activated or deactivated as needed (even as part of the process). These systems have been used for home-built systems, as well as to retrofit a modified Spire SPI-MOCVDTM 500XT system. General process interaction and results will be discussed.
Preparation and Characterization Of SrTio3 Thin Films Using ECR Plasma Assisted MOCVD
Authors: Lee Joon Sung , Song Han Wook , Yoon Dae Sung , Jun Byung Hyuk , Yu Byoung Gon , Jiang Zhong Tao , Lee Won Jong , No Kwangsoo 
Published: April 2011

ABSTRACTSrTiO3 thin films were prepared on Si(p-type 100) and Pt/SiO2/Si substrates using ECR plasma (or without ECR plasma) assisted MOCVD. Sr(TMI-D)2 and Ti-isopropoxide were used as Sr and Ti metal organic sources, respectively. Perovskite SrTiO3 films were obtained at relatively low temperature of 500°C (using ECR oxygen plasma. Experimental results indicated that higher deposition temperature and ECR oxygen plasma increase the crystallinity, the dielectric constant and the leakage current density. The dielectric constant and the dielectric loss were 222 and 0.04, respectively, for 1234 Å thin SrTiO3 film (Sr/(Sr+Ti)=0.5). The leakage current density was 3.78 × 10−7 A/cm2 at 1.0V, and the dielectric breakdown field was 0.57MV/cm. SEM analyses showed that SrTiO3 films have a uniform and fine grain structure. In terms of step coverage, a lateral step coverage of 50% at 0.8 μm step (the aspect ratio was 1) was obtained with the thickness uniformity of ± 0.5% and the composition uniformity of ±1.2% at 4′′ wafer.
The Preparation and Characterization of Lithium Cobalt Oxide thin Films by LPCVD
Authors: Kenny L.T. , Breitkopf R.C. , Haas T.E. , Goldner R.B. 
Published: April 2011

ABSTRACTLPCVD thin films of lithium cobalt oxide (LiCoO2) were grown using tertbutyllithium (t-BuLi) and cyclopentadienyl cobalt dicarbonyl (CoCp(CO)2) as precursors in a cold-walled vertical reactor. Deposition rates were found to be as high as 25 A/s. Lithium to cobalt ratios (Li/Co) in the films were found to increase with increasing Ar carrier gas flow rates in the t-BuLi line while they were found to decrease with increasing system pressure. Electrochemical measurements show typical film open circuit voltages (OCV) for as-prepared films to be between 3.30 and 3.60 V vs. Li. Atomic Force Microscopy shows a striated, crystalline film formed at substrate temperatures (Ts) as low as 400 C with grain sizes as large as 200 nm in length.
Growth via Mocvd and Characterization Of GaN and AlxGa1−xN(0001) Alloys for Optoelectronic and Microelectronic Device Applications
Authors: Davis Robert F. , Weeks T. W. , Bremser M. D. , Ailey K. S. , Perry W. G. 
Published: April 2011

ABSTRACTMonocrystalline GaN(0001) thin films have been grown at 950°C on high-temperature, 100 nm thick, monocrystalline AIN(0001) buffer layers previously deposited at 1100°C on α(6H)-SiC(0001)si substrates via MOCVD in a cold-wall, vertical, pancake-style reactor. AlxGa1−xN films (0≤x≤1) were grown directly on the same SiC surface at 1100°C. Abrupt heterojunctions among the alloy composition were demonstrated. All films possessed a smooth surface morphology and were free of low-angle grain boundaries and associated oriented domain microstructures. Double-crystal x-ray rocking curve measurements for the GaN(0004) reflection for simultaneously deposited 1.4 μm films revealed FWHM values of 58 and 151 arcsec for materials grown on on-axis and off-axis material, respectively. The corresponding values for the AIN(0004) buffer layers were ≈ 200 and ≈400 arc sec, respectively. A similar relationship was found for the alloys for 0≤x≤0.2. The PL spectra of the GaN films deposited on both vicinal and on-axis substrates revealed strong bound exciton emission with a FWHM value of 4 meV. The spectra of these films on the vicinal substrates were shifted to a lower energy, indicative of films containing residual tensile stresses. A peak believed to be associated with free excitonic emission was also observed in each on-axis spectrum. Rutherford backscattering, Auger depth profiling and energy dispersive analysis were used to determine the AIN/GaN ratios in the alloys. Cathodoluminescence of solutions with x<0.5 exhibited strong near band edge emission with a FWHM as low as 31 meV. The band gaps were determined via spectral ellipsometry. Undoped GaN and A1xGa1−xN films were too resistive for accurate Hall-effect measurements. Controlled n-type Si-doping in GaN and AlxGa1−xN (for x≤0.4) was achieved for net carrier concentrations ranging from approximately 2×1017 cm−3 to 2×1019 (AlxGa1−xN) or to l × 1020 (GaN) cm−3. Mg-doped, p-type GaN was achieved with nA−nD = 3 × 1017 cm−3, p ≈ 7 Ω cm and μ ≈ 3 cm2/V·s.
MOCVD Growth Of GaxIn1−xAs1−ySby and GaxIn1−xSb ALLOYS: Effect of Growth Parameters on Their Solid Compositions
Authors: Zhang Baolin , Zhou Tianming , Jiang Hong , Ning Yongqiang , Li Shuwei , Jin Yixin 
Published: April 2011

ABSTRACTQuaternary GaxIn1−xAs1−ySby and ternary GaxIn1−xSb alloys have been grown by metalorganic chemical vapor deposition (MOCVD). The effects of growth parameters on the solid compositions, x, y for GaxIn1−xAs1−ySby and x for GaxIn1−x Sb alloys are described in detail. Concentrations of the reactants have major effects on the corresponding solid compositions in the two kinds of alloys. The growth temperature dependence of the solid compositions in both GaxIn1−xAs1−ySby and GaxIn1−xSb was obviously observed and the growth kinetic factor was considered to account for this dependence. It was found that III/V ratio in vapor has a great effect on x in GaxIn1−xSb alloy but little effect on x and y in GaxIn1−xAs1−ySby alloy.
Mocvd Routes To Thin Films For Superconducting Applications. Precursor Synthesis and Film Processing Issues
Authors: Marks T. J. , Belot J. A. , Hinds B. J. , Chen J. , Studebaker D. , Lei J. , Chang R. P. H. , Schindler J. L. , Kannewurf C. R. 
Published: April 2011

ABSTRACTLow pressure metal-organic chemical vapor deposition has been used to grow dielectric thin films of the tetragonal perovskites LaSrGaO4 and PrSrGaO4 on (110) LaAlO3 using the volatile metal sources Pr(dpm) 3, La(hfa) 3•tri, Ga(dpm) 3, and Sr(hfa) 2•tet (dpm = dipivaloylmethanate, hfa = hexafluoroacetylacetonate, tet = tetraglyme, and tri = triglyme). The PrSrGaO4, a new ternary oxide, was found to have a body-centered tetragonal lattice with a = b = 3.80 and c = 12.59 Å. Epitaxial c-axis oriented growth of these materials has been revealed by both x-ray and electron diffraction, with an average surface roughness, measured by AFM, of 1.2 nm for LaSrGaO4 and 3.0 nm for PrSrGaO4. In addition to this, the ability of these materials to function as lattice-matched buffer layers for the growth of the high temperature superconductor YBa2Cu3O7−, has been explored. The superconductive properties of the YBCO layer do not indicate any degradation attributable to the buffer layers, with the onset of superconductivity displaying a sharp metal-superconductor transition at Tc = 87.3 K and 84.5 K for the LaSrGaO4 and PrSrGaO4 systems, respectively.
Development of Novel Nickel(β-Diketonate)2.Ligand Complexes as Precursors for Mocvd of Nickel and Nickel Oxide
Authors: Spee Carel I.M.A. , Linden Hans L. , Mackor Adri , Timmer Klaas , Meinema Harry A. 
Published: April 2011

ABSTRACTVolatile and thermally stable nickel complexes have been prepared by the reaction of fluorine substituted, nickel β–diketonates with neutral (poly)oxygen and (poly)nitrogen donor ligands.These complexes, which have low melting points, have been applied as precursors in MOCVD experiments directed on nickel and nickel oxide deposition. Investigations into the deposition of NiO in porous YSZ via particle precipitation MOCVD, for the development of an anode for a planar Solid Oxide Fuel Cell, are reported.
Modelling A Diamond Film Heatsink For GaAs Lasers
Authors: Reeves Geoffrey. K. , Shi Sanlin 
Published: April 2011

ABSTRACTMany applications for lasers require them to run at high power densities, and subsequent thermal effects can degrade their operation or limit their performance. The incorporation of a thin film of diamond in-between a laser diode and its heatsink can bring about improved laser operation through a reduction in operating temperature and temperature gradients. This paper describes the use of finite element techniques to determine the temperature distribution within a double-heterostructure laser diode and its heatsink. In the model, the diode is mounted p-side down on a copper heatsink with various thicknesses of diamond film being incorporated between the diode and the heatsink. The importance of using the correct dimensions for the diamond film are demonstrated. Various heatsink-diamond film configurations were experimentally constructed and the temperature of the active laser region measured by the nulling technique (monitoring the lasing wavelength as temperature changes). This temperature was compared to that predicted for the active region from the numerical model in order to verify the accuracy and limitations of the numerical model.
A Study of Free- and Bound-Exciton Recombination in Device Quality Diamond
Authors: Sharp S. J. , Collins A. T. 
Published: April 2011

ABSTRACTA cathodoluminescence (CL) study of free- and bound-exciton recombination in high purity high pressure high temperature (HPHT) synthetic diamond is presented, including temperature dependence measurements of the free-exciton intensity and luminescence decaytime. The results are compared with those from device quality diamond produced using the chemical vapour deposition (CVD) process.
Electronic Structure of Polycrystalline PECVD Diamond Surfaces
Authors: Humphreys T. P. , Malta D. P. , Thomas R. E. , Posthill J. B. , Mantini M. J. , Markunas R. J. 
Published: April 2011

ABSTRACTUltraviolet and X-ray photoelectron spectroscopy techniques have been employed in a preliminary study of the electronic structure of polycrystalline diamond films that have been grown on Si substrates by if-plasma enhanced chemical vapor deposition using water/ethanol growth chemistries. In particular, polycrystalline diamond films with distinctly different surface morphologies and Raman scattering characteristics have been investigated. Corresponding ultraviolet photoemission spectra from air-exposed samples have shown the presence of a prominent low-energy secondary electron emission peak indicative of a negative electron affinity (NEA) surface. Chemical stability of the polycrystalline diamond NEA surface has been demonstrated following conventional acid cleans and hydrogen plasma processing. In contrast, an oxygen (20%)/Ar plasma exposure has been shown to extinguish the photoemission of low-energy secondary electrons and remove the NEA. However, by employing a high-temperature anneal at 750 °C for 15 min in ultra-high vacuum the NEA surface can be restored. Compared to NEA single crystal diamond surfaces the photoexcited low-energy electron emission from chemical vapor deposited polycrystalline diamond films is more robust.
Novel Technique to Produce Strongly Adherent Diamond Films on Fe- and Ni-Base Alloys
Authors: Monteiro Othon R. , Wang Zhi , Brown Ian G. 
Published: April 2011

ABSTRACTAn evaluation of the use of intermediate layers for promoting adhesion between diamond and Fe and Ni base alloys is presented. The lack of adhesion between diamond and such alloys has prevented its use as a protective coating in applications at intermediate temperatures. In this study we use a combination of plasma assisted deposition techniques together with controlled bias of the substrate in order to deposit intermediate layers, and simultaneously achieve a thorough intermixing of the elements at the interface, in order to increase the adhesion between the layers. We have compared the performance of different carbide forming metals, as well as other materials. Properties considered in the selection of the appropriate intermediate layers are: chemical affinity with carbon, thermal expansion coefficient, mechanical properties, and adhesion to diamond and to the base metal as well. In the case of multiple layers, adhesion strength was measured after every new layer was deposited, in order to identify any weak links of the composite structure. Transmission electron microscopy was used to determine the microstructure and phases. An analysis is provided of the resulting performance on the basis of the microstructure.
The Control Of Intrinsic Stresses In Cvd Diamond Films With Multistep Processing
Authors: Nijhawan S. , Jankovsky S. M. , Sheldon B. W. 
Published: April 2011

ABSTRACTThe role of intrinsic stresses in diamond films is examined. The films were deposited on (100) Si substrates by microwave plasma-enhanced chemical vapor deposition. The total internal stresses (thermal and intrinsic) were measured at room temperature with the bending plate method. The thermal stresses are compressive and arise due to the mismatch in thermal expansion coefficient of film and substrate. The intinsic stresses were tensile and evolved during the deposition process. These stresses increased with increasing deposition time. A 12 hour intermediate annealing treatment was found to reduce the tensile stresses considerably. The annealing treatment is most effective when the diamond crystallites are undergoing impingement and coalescence. This is consistent with the theory that the maximum tensile stresses are associated with grain boundary energetics.
Effects of Substrate Bias on the Nucleation of Diamond Films Studied by Atomic Force Microscopy
Authors: Sánchez G. , Polo M. C. , Wang W. L. , Esteve J. 
Published: April 2011

ABSTRACTThe nucleation stage of diamond on silicon substrates was studied by atomic force microscopy. Samples were grown by hot filament chemical vapor deposition and substrate biases from -200 ν to +75 ν were investigated. The effects of the process on the substrate as well as on the morphology of the crystallites were observed using an atomic force microscope operating in tapping mode. It was observed that both the density and morphology of the diamond crystallites were greatly dependent on the applied bias values. The highest nucleation density was achieved for the -200 ν bias, when a plasma around the substrate holder was formed.
Mass Transport Effects In Selectively Deposited Diamond Thin Films
Authors: Kwan Michael C. , Gleason Karen K. 
Published: April 2011

ABSTRACTIn order to study the effects of gas phase transport on the growth of hot-filament chemical vapor deposited (HFCVD) diamond, crystallites were selectively grown on a pre-nucleated, oxygen plasma patterned silicon wafer. Growth rate differences across the substrate were observed from scanning electron micrographs. The deposition system was then modeled with a three dimensional finite difference scheme that employed gas phase diffusion of a single growth limiting species from the hot filament to the surface coupled with a first order surface reaction. The variations in the predicted gas phase concentration directly above the surface were adjusted to match the observed growth rate differences through the Dahmk6hler number which was then used to calculate a first order surface reaction coefficient. This value was compared to published reaction coefficients for the abstraction of a surface H-atom by a gas-phase H-atom.
A Theoretical Study Of The Energetics And Vibrational Spectra Of Oxygenated (100) Diamond Surfaces
Authors: Skokov S. , Weiner B. , Frenklach M. 
Published: April 2011

ABSTRACTStatic quantum ab initio and quantum semiempirical molecular dynamics calculations were employed to study reconstructions of (100) diamond surfaces in presence of hydrogen and oxygen. The results indicate that the energetically most favorable structures of oxygenated surfaces are those with chemisorbed hydroxyl groups. It was found that hydrogen bonds are formed among chemisorbed oxygenated species. The formation of these hydrogen bonds is shown to be an important factor in stabilization of adlayers. A number of important vibrational modes characteristic of oxygenated diamond surfaces were identified. The analysis of surface vibrational spectra demonstrates the influence of the local environment on the position of vibrational modes and can be useful for interpretation of experimental data.
Hydrogen Plasma Treatment of Natural and Homoepitaxial Diamond
Authors: Rawles R. E. , Gat R. , Morris W. G. , D'Evelyn M. P. 
Published: April 2011

ABSTRACTAs-polished and homoepitaxial diamond (100)- and (111)-oriented single crystals, natural diamond powders of 0.12-6 μm diameter, and high-pressure/hightemperature (HPHT) diamond powders of 50-100 μm diameter were treated in a microwave hydrogen plasma under four sets of conditions. Negligible changes in the weights (±10 μg) of the as-polished and homoepitaxial diamonds were observed.Post-treatment atomic force microscopy (AFM) showed a combination of smoothing and pit formation on (100) surfaces, the details of which were sensitive to the structure of the starting surface. Asymmetric pits formed on an as-polished (111) surface, but no qualitative changes in the structure of highly defective (100) and (111) films were observed. Natural diamond powders, which were quite irregular and rough prior to treatment, became markedly smoother and well-faceted, as observed by scanning electron microscopy (SEM). The degree of faceting was sensitive to plasma power level but was independent of H2 flow rate. The size and degree of faceting appeared to be the same after plasma treatment for isolated and closelypacked particles; however, the latter fused into a quasi-continuous film. “Regrown” crystallites were observed on the surfaces of synthetic type Ib diamond particles following plasma treatment. We argue that surface diffusion is the dominant mechanism for the observed morphological changes.