bluuebunny/crossref_metadata_2025_split huggingface dataset:
High Sensitivity Photochemical Sensors Based on Amorphous Silicon
Authors: Fortunato E. , Malik A. , Séco A. , Maçarico A. , Martins R. 
Published: April 2011

ABSTRACTHydrogenated amoiphous silicon photochemical sensors based on Pd-MIS structures were produced by Plasma Enhanced Chemical Vapor Deposition with two different oxidized surfaces (thermal and chemical oxidation). The behaviour of dark and illuminated current-voltage characteristics in air and in the presence of a hydrogen atmosphere is explained by the changes induced by the gases in the work function of the metal, modifying the electrical properties of the interface. The photochemical sensors produced present more than 2 orders of magnitude variation on the reverse dark current when in presence of 400 ppm hydrogen to which it corresponds a decrease of 45% on the open circuit voltage.
Gallium Nitride Doped with Zinc and Oxygen - The Crystal for the Blue Polarized Light-Emitting Diodes
Authors: Sidorov V. G. , Drezhuk A. G. , Zaitsev M. V. , Sidorov D. V. 
Published: April 2011

ABSTRACTEpitaxial layers and light-emitting i-n-structures with the active region of GaN doped simultaneously with zinc and oxygen have been grown. Effective up to 60% blue polarized luminescence has been observed. Investigated properties of grown layers and structures are presented. A discussion of issues related to GaN utilization based on its found properties is also included.
Raman Scattering and Photoluminescence of Mg Doped GaN Films Grown by Molecular Beam Epitaxy
Authors: Popovici G. , Xu G. Y. , Botchkarev A. , Kim W. , Tang H. , Salvador A. , Strange R. , White J. O. , Morkoζ H. 
Published: April 2011

ABSTRACTRaman, photoluminescence, and Hall measurements are reported for Mg doped GaN films grown by molecular beam epitaxy. The compressive and tensile stress determined by the Raman shift of the phonon lines is due to the growth conditions rather than the presence of Mg in the film. The photoluminescence peak of near band-to-band transitions is also shifted to larger (smaller) energies by the compressive (tensile) stress. The study of the longitudinal optical phonon of the Ai branch shows that its Raman line shape is affected not only by phonon-plasmon interactions but by the crystalline quality of the film, as well.
Optical Anisotropy of the Optical Response for Strained GaN Epilayers Grown Along the <10–10> Direction
Authors: Andenet A. , Gil B. , Le Vaillant Y.-M. , Clur S. , Briot O. , Aulombard R. L. 
Published: April 2011

ABSTRACTGroup theory states that the spectroscopy of excitons in GaN epilayers grown with biaxial stress on M Plane (10–10)-oriented substrates is strongly anisotropie in the growth plane, in contrast to the situation if growth occurs on conventional C plane substrates. In addition, we predict existence of nine radiative transitions instead of five, three for each family of A, B, and C excitons. We calculate the in-plane anisotropy and show that, due to the crossed configuration of the wurtzite crystal field and the built-in strain one, the A exciton is significantly coupled to the electromagnetic field in π polarization (E//c).
A Chemical and Structural Study of the AlN-Si Interface
Authors: Beye R. , George T. 
Published: April 2011

AbstractSamples of AlN grown on silicon [111] substrates were examined using electron energy loss spectroscopy (EELS) and selected area diffraction (SAD) with high-resolution transmission electron microscopy (TEM) to determine the source of out-of-plane tilts and in-plane rotations of the AlN crystallites at the Si interface. SAD results indicate that the interfacial crystallites are sheared along vertical planes, with random, intercrystalline rotation. The interfacial phenomena are believed to be the result of Si-Al-N interaction. Analytical experiments show no evidence of silicon nitride formation, witnessed by nitrogen-K peak shape, up to the Si interface. No evidence of substrate-epilayer interdiffusion was observed. Chemical interaction within one monolayer of the interface is therefore suspected as the cause of the epilayer tilts and rotations.
Growth of Ternary Silicon Carbon Nitride as a New Wide Band Gap Material
Authors: Cheni L. C. , Chen C. K. , Bhusari D. M. , Chen K. H. , Wei S. L. , Chen Y. F. , Jong Y. C. , Lin D. Y. , Li C. F. , Huang Y. S. 
Published: April 2011

ABSTRACTGrowth of pure crystalline carbon nitride (c-CN) with crystal sizes large enough to enable measurement of its properties has not been achieved so far. We report here that incorporation of silicon in the growth of CN can promote formation of large, well faceted crystallites. Crystalline thin films of SiCN have been grown by microwave plasma-enhanced chemical vapor deposition using CH4, N2, and SiH4 gases. Auger electron spectroscopy, scanning electron microscopies, and X-ray diffraction spectroscopy have been employed to characterize the composition, the morphology and the structure of the films. The new crystalline ternary compound (C; Si)xNy exhibits hexagonal structure and consists of a network wherein the Si and C are believed to be substitutional elements. While the N content of the compound is about 35%, the extent of Si substitution varies from crystal to crystal. In some crystals, the Si content can be as low as 10%. Optical properties of the SiCN compounds have been studied by photoluminescence (PL) and piezoreflectance (PzR) spectroscopies. From the PzR measurement, we determine the band gap of the new crystals to be around 3.8 eV at room temperature. From the PL measurement, it is found that the compounds have a strong subband-gap emission centered around 2.8 eV at room temperature, which can be attributed to the effect of defects containing in the crystals.
Current Transport in W and WSIX Ohmic Contacts to Ingan and Inn
Authors: Vartuli C. B. , Pearton S. J. , Abernathy C. R. , MacKenzie J. D. , Lovejoy M. L. , Shul R. J. , Zolper J. C. , Baca A. G. , Hagerott-Crawford M. , Jones K. A. , Ren F. 
Published: April 2011

ABSTRACTThe temperature dependence of the specific contact resistance of W and WSi0.44 contacts on n+ In0.55Ga0.35N and InN was measured in the range -50 °C to 125 °C. The results were compared to theoretical values for different conduction mechanisms, to further elucidate the conduction mechanism in these contact structures. The data indicates the conduction mechanism is field emission for these contact schemes for all but as-deposited metal to InN where thermionic emission appears to be the dominant mechanism. The contacts were found to produce low specific resistance ohmic contacts to InGaN at room temperature, ϱc ∼ 10-7 Ω ·cm2 for W and ϱc of 4× 10-7 Ω ·cm for WSix. InN metallized with W produced ohmic contacts with ϱc ∼ 10-6 Ω ·cm and ϱc ∼ 10-6 Ω ·cm. for WSix at room temperature.
Low Resistance Contacts to P-Type GaN
Authors: Kim Taek , Khim Jinseok , Chae Suhee , Kim Taeil 
Published: April 2011

ABSTRACTWe report the low resistance ohmic contacts to p-GaN using a Pd/Au bimetal scheme. A specific contact resistivity of 9.1 × 10-3 Ω-cm2 was obtained after annealing. The metallization was e-beam evaporated on 2 μm-thick p-GaN (∼ 9 × 1016/cm3) layers grown on c-plane sapphire substrates by metalorganic chemical vapor deposition (MOCVD). The comparison with other contacts showed that the contact resistivity of the Pd/Au contacts was at least one order smaller than those of Pt/Au and Ni/Au contacts.
Pulsed Laser Deposition of Gallium Nitride on Sapphire
Authors: Talyansky V. , Vispute R. D. , Sharma R. P. , Choopun S. , Downes M. J. , Venkatesan T. , Li Y. X. , Salamanca-Riba L. G. , Wood M. C. , Lareau R. T. , Jones K. A. 
Published: April 2011

ABSTRACTWe have fabricated high quality single crystalline GaN films on sapphire (0001) substrates using pulsed laser deposition. Our best GaN films on sapphire (0001) featured the FWHM of the GaN (002) peak rocking curve of 7 arcmin, the RBS minimum yield of only 3%, and the energy gap width of 3.4 eV. The effect of the deposition temperature on the crystalline quality of the films is discussed.
Optimization of the Ast Hot Liner™ for Sub-Micron Production
Authors: Riley Terrence J. , Bremensdorfer Rolf , Marcus Steve 
Published: April 2011

ABSTRACTIn an effort to develop an emissivity independent temperature measurement technique for the AST Rapid Thermal Processor (RTP), AST has conceived of the Hot Liner™. The Hot Liner is a silicon nitride coated silicon wafer which is permanently installed in the process chamber, immediately below the wafer. The pyrometer, which is calibrated to a production wafer, views the constant emissivity Hot Liner to produce repeatable temperatures on product wafers regardless of their backside emissivity.Given the repeatability of the Hot Liner, the wafer temperature uniformity must then be optimized in order to achieve 0.25μm capable processing. AST has developed a methodology which incorporates process monitors (ion implanted test wafers) to establish process uniformity in addition to multiple thermocouple wafers to verify across wafer temperature uniformity. The process monitors are used to separately optimize the ramp and steady state steps in the production recipe.Utilizing the AST methodology to optimize processing with the Hot Liner has allowed AMD to significantly improve its RTA processing. The Hot Liner greatly decreases backside and pyrometer effects which yields limited wafer to wafer variation (< 5C, 3σ). In combination with the optimization process this results in excellent within wafer uniformity (< 3C, 3σ).
Ultra Low Thermal Budget Rapid Thermal Processing for Thin Gate Oxide Dielectrics: Reduction of Suboxide Transition Regions in Low Temperature Processed Si/SiO2Structures by A 900°C 30 Second Rapid Thermal Anneal
Authors: Lucovsky G. , Hinds B. 
Published: April 2011

ABSTRACTDevice quality gate dielectric heterostructures have been prepared using a three step plasma/rapid thermal sequence [1] in which kinetic effects determine the time-temperature aspects of the processing. The steps for forming the interface and for depositing dielectric layers have been performed at low temperature, ∼300°C, by plasma-assisted processing. Following this a low rapid thermal anneal (RTA) provides interface and bulk dielectric chemical and structural relaxations, thereby yielding device performance and reliability essentially the same as obtained using higher thermal budget conventional or rapid thermal processing.
Uniform Ultra-Thin Oxides Grown by Rapid Thermal Oxidation of Silicon in N2O Ambient
Authors: Xing G. C. , Lopes D. , Miner G. E. 
Published: April 2011

ABSTRACTIn this paper, we report the study of rapid thermal oxidation of silicon in N2O ambient using the Applied Materials RTP Centura rapid thermal processor, and N2O oxide thickness and compositional uniformities with respect to gas flow rate and wafer rotation speed as well as other process parameters. It was found that N2O oxide uniformity is strongly dependent on gas flow rate and wafer rotation speed in addition to process pressure. With optimized setting of the process parameters, excellent oxidation uniformities (one sigma < 1%) were obtained at atmospheric pressure N2O ambient. Nitrogen concentrations of such uniform oxides grown at 1050°C atmospheric pressure N2O oxidation processes were 1.7% for a 40Å oxide and 2.5% for a 60Å oxide, respectively, as characterized by SIMS analysis.
Aluminum Gate Metallization for AMLCDs
Authors: Kim Joo-Han , Kanicki Jerzy , den Boer Willem 
Published: April 2011

ABSTRACTAluminum metallization incorporating the anodic aluminum oxide has been optimized for high-performance amorphous silicon thin film transistors (a-Si:H TFTs). For such a device, the off-current is less than the picoampere and the ON-OFF current ratio is ∼2×107, the field effective mobility is about 1.25 cm /Vsec in the linear region and the subthreshold swing is about 0.38 V/decade. These electrical performances are acceptable for high-definition AMLCDs.
Very-Low Surface Roughness in Laser Crystallized Polycrystalline Silicon
Authors: Mourgues K. , Pichon L. , Raoult F. , Mohammed-Brahim T. , Briand D. , Bonnaud O. , Lemoine D. , Boher P. , Sthelé M. , Sthelé J. L. 
Published: April 2011

ABSTRACTExcimer laser (ECL) crystallization of silicon films on low temperature substrates is one of the most promising technique for large-area polycrystalline silicon films. Crystallization techniques using pulsed-ECL were extensively studied. They are characterized by films with high structural and electrical properties but low uniformity. In this way, the technology using single shot ECL with very large excimer laser (VEL) may be very promising. It was used for the crystallization of amorphous undoped films deposited by PECVD or by LPCVD The LPCVD technique is the most commonly used deposition technique of silicon. It presents numerous advantages and the hydrogen content in the films, known to constitute a drawback in the crystallization process leading to an increased surface roughness, is negligible (∼1 at.%). However, even with these low hydrogen content LPCVD films, high surface roughness is observed after the laser crystallization. Hence surface roughness appears as one of the major problems to be solved in the high performance TFT's realization from laser crystallized films.In this work, the reduction of the surface roughness, determined from Atomic Force Microscopy observations, is presented. This reduction originated from the use of a surface oxidation and an etch treatment to remove the oxide. The mean height of the roughness is then reduced by about 50%.Using these low surface roughness polycrystalline films, TFT's are then realized.
Fabrication Technologies of Field Emitter Arrays
Authors: Choi J. H. , Ryu Y. S. , Kang J. H. , Jang J. E. , Kim J. M. , Hong J. P. , Lim D. Y. , Michine V. 
Published: April 2011

ABSTRACTTotal internal reflection (TIR) holographic lithography is studied as a new method for field emitter array (FEA) fabrication. Four basic parameters of the process - scan speed, laser power, focus distance and step distance, are analyzed to optimize the hole patterns. In addition, the characteristics of the Aluminum (Al) parting layer are studied to minimize the stress produced by Molybdenum (Mo) layer during Spindt-type tip formation process.
Mocvd SrS:Ce for Applications in Electroluminescent Devices
Authors: Endisch D. , Barth K. , Lau J. , Peterson G. , Kaloyeros A. E. , Tuenge D. , King C. N. 
Published: April 2011

ABSTRACTSrS:Ce is an important material for full color electroluminescent (EL) flat panel displays. Using a combination of SrS:Ce/ZnS:Mn and appropriate color filters high quality full color displays have been demonstrated [1]. Major issues for commercially viable process integration of SrS:Ce are the combination of high luminance, high growth rate, and process temperatures below 600°C for compatibility with low cost glass substrates. This work describes the process development and optimization of metal-organic chemical vapor deposition (MOCVD) of SrS:Ce. MOCVD is a promising candidate for deposition of SrS:Ce because it can provide the required growth rates and allows control of crystal structure and stoichiometry. Growth of SrS:Ce was performed in the temperature range from 400°C to 530°C using Sr(tmhd)2, Ce(tmhd)4, and H2S as precursors. The structure of the SrS:Ce was found to be strongly dependent on the H2S flow. A brightness of 15 fL and an efficiency of 0.22 lm/W has been achieved (40 V above threshold voltage, 60 Hz AC). Film analysis included Rutherford backscattering (RBS), X-ray diffraction (XRD), atomic force microscopy (AFM), and EL measurements. Results on the correlation between process parameters, film structure, grain size and EL performance will be presented.
Development of Large area Excimer VUV and UV Sources from a Dielectric Barrier Discharge
Authors: Zhang Jun-Ying , Boyd Ian W. 
Published: April 2011

ABSTRACTA large-area, high power density, high efficiency, and low cost excimer VUV and UV source, which is capable of producing narrow-band radiation tunable between the near UV (λ=354 nm) and the deep UV (λ=126 nm), is described.This UV source is based on the principle that the radiative decomposition of excimer states created by a dielectric barrier discharge (silent discharge) in a rare gas, such as Ar2* (λ=126 nm), Kr2* (λ=146 nm), Xe2* (λ=172 nm) or molecular rare gas-halide complexes, such as ArCl* (λ=175 nm), KrCl* (λ=222 nm), XeCl* (λ=308 nm). Conversion efficiencies (from input electrical to output optical energy) as high as 22% can be achieved under optimum conditions. This powerful and economical lamp provides a useful UV source for low temperature photon-initiated processes and is an interesting alternative to conventional UV lamps for industrial large-scale low temperature processes. For industrial large-area processing and for the deposition of highly complex structures, these narrow band VUV and UV sources with high photon fluxes have definite advantages. Several applications of these excimer sources are reviewed, including photo-deposition of dielectric and metallic thin films, photo-oxidation of silicon, surface modification, etching of polymer, and photo degradation of pollutants.
Study of Electrical Transport Across Interfaces between Wide Gap Semiconductor and Metal Oxides
Authors: Talyansky V. , Vispute R. D. , Sharma R. P. , Choopun S. , Downes M. J. , Venkatesan T. , Iliadis A. A. , Wood M. C. , Lareau R. T. , Jones K. A. 
Published: April 2011

ABSTRACTWe have grown YBa2Cu3O7 (YBCO) and Pr1.85Ce0.15CuO4 (PCCO) polycrystalline films on n-type GaN using pulsed laser deposition. The diodes fabricated out of these heterostructures exhibited a strong rectifying behavior with transport characteristics that were found to fit well to the thermionic emission model. The effective barrier heights for YBCO and PCCO based diodes were found to be 788 meV and 236 meV, respectively. Rutherford Backscattering structural analysis of the heterostructures is also discussed.
Effect of Lattice Strain on Growth Mechanisms and Electrical Transport Behavior of Epitaxial CaRuO3 Thin Films
Authors: Eom C. B. , Rao R. A. , Gan Q. , Cava R. J. , Krajewski J. J. , Suzuki Y. , Gausepohl S. C. , Lee M. 
Published: April 2011

ABSTRACTWe have observed both metallic and semiconducting behavior in epitaxial thin films of the metallic oxide CaRuO3 deposited under identical conditions on (100) SrTiO3 substrates of varying crystalline quality. X-ray diffraction studies showed that while semiconducting films with enlarged unit cells were obtained on single crystal SrTiO3 substrates, metallic films with lattice parameters close to the bulk material grew on poor crystalline quality SrTiO3 substrates. The films deposited on (100) LaAlO3 substrates consistently showed metallic behavior. Atomic force microscope images suggest that the semiconducting films had a coherent two dimensional nucleation. In contrast, three dimensional island-like incoherent growth was seen in the metallic films. It is believed that in the coherent films a strain induced substitution of the small Ru4+ cations by the larger Ca2+ cations occurs, breaking the conduction pathway within the three dimensional network of the RUO6 octahedra and leading to a metal-insulator transition. This unique phenomenon - which is not observed in bulk material - can be significant in technologically important epitaxial perovskite oxide heterostructures.
Surface Structure and Morphology of Mg-Segregated, Epitaxial Fe3O4 Thin Films on Mgo(001)
Authors: Anderson J. F. , Kuhn Markus , Diebold Ulrike , Shaw K. , Stroyanov P. , Lind D. 
Published: April 2011

ABSTRACTWe have investigated the structural and compositional changes that are induced by the segregation of substrate Mg to the surface of 1μm-thick Fe3O4 films on MgO(001). The thin films have been grown with plasma-assisted MBE, and characterization with RHEED (reflection high-energy electron diffraction), x-ray diffraction (XRD), and Superconducting Quantum Interference Device (SQUID) magnetometry show slightly strained, single-crystalline Fe3O4 films. For the surface studies, we have combined Low-Energy Electron Diffraction (LEED) and Scanning Tunneling Microscopy (STM). Initial and final surface characterization employed X-ray Photoelectron Spectroscopy (XPS) and Ion Scattering Spec-troscopy (ISS) respectively. The surfaces of the MBE-grown samples are flat and show a (√2 × √2)R45° reconstruction with respect to the Fe3O4 surface unit cell. We observe the onset of Mg segregation to the surface at around 700 K, with long, narrow extensions of terraces being observed growing along the [110] and [110] directions. Upon prolonged heating at 800 K, massive Mg segregation to the surface is observed. Heating in an oxygen atmosphere induces a 1×4 surface reconstruction, and results in extremely long (≈ 1000 Å), wide terraces.
Reactive Growth and Properties of Epitaxial Fe-Mg-O Spinel Films on (100) MgO
Authors: Senz S. , Graff A. , Teichert C. , Zimnol M. , Sieber H. , De S. K. , Oepen H. P. , Hesse D. , Kirschner J. , Gösele U. M. 
Published: April 2011

ABSTRACTEpitaxial Mg-Fe-O spinel thin films were prepared by solid state reactions between MgO(lOO) substrates and thin films or vapors of iron oxide. Iron or iron oxide was deposited by electron beam evaporation in an oxygen background pressure onto a heated MgO crystal. The formation of MgFe2O4 at high temperatures proceeds via cation counter-diffusion in the fixed oxygen sublattice. Depending on substrate temperature, oxygen partial pressure and target material, epitaxial spinel films of different composition and magnetic properties were obtained. Crystal structure, composition and sub-micron morphology were investigated by RBS, XRD, TEM/SAED and EDX. Magnetic hysteresis loops were recorded at room temperature using the magneto-optic Kerr effect. Thickness interference fringes observed by XRD confirm the growth of smooth films. The main feature found in TEM plane view samples is a network of cation antiphase boundaries. The film composition measured by RBS varied from Fe2+ɛO3 films deposited at 340 °C substrate temperature to a solid solution of Fe2+E03 and MgFe2O4 at 500 °C to MgFe2O4 above 800 °C. EDX line-scans show a single phase MgFe2O4 spinel for a substrate temperature of 850 °C, without variation of composition with position or depth. At substrate temperatures higher than 800 °C Fe2+ was additionally dissolved in the MgO substrate, forming a FexMg1-xO solid solution.
Oxide Epitaxial Lift-Off (OELO)
Authors: Eddy M. M. , Hanson R. , Rao M. R. , Zuck B. , Speck J. S. , Tarsa E. J. 
Published: April 2011

ABSTRACTEpitaxially grown oxides of both SrTiO3 (STO) and YBa2Cu3O7-δ (YBCO) have been removed from their growth substrate and transferred for integration into other circuits (microwave devices) and onto other substrate material (glass). The enabling element in the separation process is the high selectivity of etching between YBCO and other oxide materials. Thus, a thin layer of YBCO is used as the sacrificial layer in the structure, allowing rapid etchant ingress under the device structures and separation from the growth substrate. Initial demonstrations of microwave device tuning using a lifted-off STO layer is detailed.