bluuebunny/crossref_metadata_2025_split huggingface dataset:
Two terminal large area single and double p-i-n devices for image and color recognition
Authors: Louro P. , Vieira M. , Fantoni A. , Fernandes M. , Carvalho C. Nunes de , Lavareda G. 
Published: April 2011

ABSTRACTLarge area hydrogenated amorphous silicon single and stacked p-i-n structures with low conductivity doped layers are proposed as monochrome and color image sensors. All have the same intrinsic layer and in the doped layers the resistivity and optical gap was controlled through the addition of methane to the doping gas. The current-voltage characteristics and the spectral sensitivity under different illumination conditions are analyzed. The sensor output characteristics are evaluated under different read-out voltages and scanner wavelengths. To extract information on image range, intensity and color, a modulated light beam scans the sensor active area at three appropriate bias voltages and the photoresponse in each scanning position (“sub-pixel”) is recorded. The investigation of the sensor output under different scanner wavelengths and varying electrical bias reveals that the response can be tuned, thus enabling color separation. The operation of the sensor is exemplified and supported by a numerical simulation.
Monolithically Integrated p- & n- Channel Thin Film Transistors of Nanocrystalline Silicon on Plastic Substrates
Authors: Cheng I-Chun , Wagner Sigurd 
Published: April 2011

ABSTRACTInverters made of monolithically integrated p- and n-channel thin film transistors of nanocrystalline silicon were demonstrated on both Corning 1737 glass and Kapton E polyimide substrates. The TFT's geometry is staggered top-gate, bottom-source/rain. A nc-Si:H seed layer promotes the structural evolution of the nc-Si:H channel. Electron field-effect mobilities of 15 - 30 cm2V−1s-1 and hole mobilities of 0.15 - 0.35 cm2V−1s−1 were obtained. Slightly lower carrier mobilities were observed in the TFTs made on polyimide than on glass substrates. High gate leakage currents and offsets between the supply HIGH voltages and the output voltages in the inverters indicate that the low-temperature gate dielectric needs improvement.
In-situ Observation of Silicon Epitaxy Breakdown with Real-Time Spectroscopic Ellipsometry
Authors: Teplin Charles W. , Levi Dean H. , Wang Qi , Iwaniczko Eugene , Jones Kim M. , Branz Howard M. 
Published: April 2011

ABSTRACTWe use in-situ real-time spectroscopic ellipsometry to observe the breakdown of silicon epitaxy during growth by hot-wire chemical vapor deposition (HWCVD) on Si (100) substrates. Representative data is presented for the two types of epitaxy breakdown that we have observed: 1) an immediate transition to hydrogenated amorphous silicon (a-Si:H), and 2) a slower transition where a-Si:H cones nucleate and grow until they eclipse further epitaxial growth. Simple models, consistent with transmission-electron and atomic-force micrographs, describe the evolution of both types of breakdown showing that real-time spectroscopic ellipsometry is a useful tool for monitoring the growth of epitaxial silicon.
Amorphous and Microcrystalline Silicon-based Photovoltaic
Authors: Guha Subhendu 
Published: April 2011

ABSTRACTThe last two decades have witnessed tremendous progress in the science and technology of amorphous and microcrystalline silicon-based photovoltaic. Advances in the understanding of materials and devices have led manufacturers to expand their production capacity; the production of solar panels based on this technology exceeded 25 MW in 2003. Hydrogen dilution in the active gas mixture during deposition has played a key role in improving the quality of the materials and the performance of the devices. In this paper I shall review the properties of the optimum material for device application, and discuss the production status. I shall also report on the new opportunities that are opening up for these products for space and stratospheric applications.
Structural and Electronic Properties of SiCl4-based Microcrystalline Silicon Films
Authors: Beyer Wolfhard , Carius Reinhard , Lejeune Michael , Zastrow Uwe 
Published: April 2011

ABSTRACTStructural and electronic properties of SiCl4-based microcrystalline silicon films were studied. A rather dense (non-porous) material structure is obtained near the transition to amorphous material, in particular at substrate temperatures of 250°C and above. Boron doping results in very high conductivity values while for phosphorus doping only lower values are reached. This latter effect is attributed to a different microstructure with lower crystalline fraction, higher hydrogen and chlorine content and increased porosity in highly phosphorus- doped material.
Growth of epitaxial CoSi2 from Cobalt Carbonyl on Si(100) Substrate
Authors: Singanamalla R. , Greve D.W. , Barmak K. 
Published: April 2011

ABSTRACTBeyond its applications in silicon MOSFETs, cobalt disilicide is potentially useful for the formation of epitaxially overgrown quantum dots and quantum wires. We report the formation of cobalt silicide on Si (100) and its overgrowth by silicon. Cobalt films approximately 3.5 nm in thickness have been deposited on Si (100) using a cobalt carbonyl organometallic source. We observe by reflection high-energy electron diffraction (RHEED) that the deposited cobalt film is converted to epitaxial cobalt disilicide upon annealing at 850°C, considerably higher than the silicidation temperature typically observed for sputtered cobalt. We explain this behavior with the aid of secondary ion mass spectrometry (SIMS) profiling of the carbon and oxygen impurity concentrations. The cobalt disilicide layers have been overgrown with silicon at 625°C. We contrast the surface topology measured by atomic force microscopy (AFM) just after cobalt growth, after silicidation, and after overgrowth with silicon. The surface has been observed to be rough after growth of silicon by silane exposure for 15 min at 625°C at 0.55 mTorr of chamber pressure. The surface roughness prevails even after overgrowing with silicon for 60 min at same chamber temperature and pressure conditions.
BIC Formation and Boron Diffusion in Relaxed Si0.8Ge0.2
Authors: Crosby R. T. , Radic L. , Jones K. S. , Law M. E. , Thompson P.E. , Liu J. , Klimov M. , Craciun V. 
Published: April 2011

ABSTRACTThe relationships between Boron Interstitial Cluster (BIC) evolution and boron diffusion in relaxed Si0.8Ge0.2 have been investigated. Structures were grown by Molecular Beam Epitaxy (MBE) with surface boron wells of variant composition extending 0.25 [.proportional]m into the substrate, as well as boron marker layers positioned 0.50 [.proportional]m below the surface. The boron well concentrations are as follows: 0, 7.5×1018, 1.5×1019, and 5.0×1019 atoms/cm3. The boron marker layers are approximately 3 nm wide and have a peak concentration of 5×1018 atoms/cm3. Samples were ion implanted with 60 keV Si+ at a dose of 1×1014 atoms/cm2 and subsequently annealed at 675°C and 750°C for various times. Plan-view Transmission Electron Microscopy (PTEM) was used to monitor the agglomeration of injected silicon interstitials and the evolution of extended defects in the near surface region. Secondary Ion Mass Spectroscopy (SIMS) concentration profiles facilitated the characterization of boron diffusion behaviors during annealing. Interstitial supersaturation conditions and the resultant defect structures of ion implanted relaxed Si0.8Ge0.2 in both the presence and absence of boron have been characterized.
Enhancement of Boron Activation in Shallow Junctions by Hydrogen
Authors: Vengurlekar A. , Ashok S. , Kalnas C. E. , Theodore N. D. 
Published: April 2011

ABSTRACTThe ability to activate greater amounts of dopants at lower temperatures is a persistent contingency in the continual drive for device scaling in Si microelectronics. We report on the effect of incorporating atomic hydrogen on the activation of implanted boron in shallow junctions. Hydrogen incorporation into the sample was carried out by exposure to an electron cyclotron resonance (ECR) hydrogen plasma. Enhanced activation was observed in hydrogenated samples for post-implantation annealing temperatures of 450°C and below, as measured by spreading resistance profilometry, and confirmed by identical boron atomic profile in hydrogenated and unhydrogenated samples. The enhancement in boron activation at lower temperature is attributed to the creation of vacancies in the boron-implanted region, the lattice-relaxation effect by the presence of atomic hydrogen, and the effect of atomic hydrogen on boron-interstitial cluster formation.
Textural Evolution of Cu Damascene Interconnects after Annealing
Authors: Cho Jae-Young , Lee Hyo-Jong , Kim Hyoungbae , Szpunar Jerzy A. 
Published: April 2011

AbstractTextural evolution of Cu interconnects having a different line width was investigated after annealing. Texture was measured on the surface of Cu interconnects using EBSD (electron backscattered diffraction) techniques including GBCD (grain boundary character distribution). To analyze a relationship between the stress distribution and textural evolution in the samples investigated, the micro stresses were calculated for the different line width at 200°C using FEM (finite element modeling). In this investigation, it was found that the inhomogeneity of stress distribution in Cu interconnects is an important factor is necessary for understanding textural transformation after annealing. A new interpretation of textural evolution in damascene interconnects lines after annealing is suggested, based on the state of stress and the growth mechanisms of Cu electrodeposits.
Patterned growth of organic small-molecule layers
Authors: Steudel Soeren , Janssen Dimitri , Verlaak Stijn , Heremans Paul 
Published: April 2011

AbstractWe will demonstrate a novel approach to the problem of patterning organic small molecule layers, which is compatible with printing techniques. By locally changing the chemistry of the dielectric surface by means of Self-Assembly Monolayers (SAM), we predefine active and passive areas of the circuit. The subsequent growth of the organic film by sublimation takes place under growth conditions which cause the formation of a high-mobility, well- connected two-dimensional (2D) grains in the predefined active area contrasting with ill- connected, low-mobility 3D-grains in the passive area. We will explain this patterned growth in terms of a microscopic theory of nucleation of organic semiconductor on inert substrates and present experimental results.
Reel-to- Reel Cassette Cluster Tool System for Thin Film Transistor and Four Terminal Solar Cell Fabrication
Authors: Madan Arun 
Published: April 2011

AbstractWe present a new type of system architecture to fabricate thin film silicon devices on flexible substrates, which uses the inherent advantages of a cluster tool normally used in the production of amorphous silicon thin film transistors, solar cells, etc. In this, the flexible substrate material is contained within a cassette which includes a reel to reel operation. As in the current cluster tools used for planar substrates, the cassette is transported to a process chamber using a robotic arm. When the entire roll in the cassette has been processed, it is transported into other chambers for further processing. We also show that a four terminal device structure (e.g. amorphous Si and stable low band gap nano-crystalline Si cells) potentially can lead to high efficiency (>15%), stable, low cost solar cells on a plastic substrate. Lastly we discuss the use of a pulsed PECVD deposition technique, which allows that the structure of the nano-crystalline Si films can be altered from 111 to 220 in a controllable way at a low temperature of <170C.
Crack Trapping Effect of Recalcitrant Grain Boundary Islands in Fe-3wt%Si Alloy
Authors: Qiao Yu , Kong Xinguo 
Published: April 2011

AbstractIn the polycrystalline Fe-Si alloy when a cleavage front transmits from one grain to another, it first penetrates stably through the grain boundary at a number of break-through points that distribute along the front quasi-periodically. As the critical energy release rate is reached, the unstable crack jump occurs and the recalcitrant grain boundary islands (RGBI) between the break-through points are left behind the verge of propagating, bridging across the crack flanks. Eventually, the RGBI are sheared apart, which leads to a 10%-30% increase in fracture resistance. In this paper, this process is investigated through an energy analysis. The influence of the size/spacing ratio of RGBI on the grain boundary toughness is discussed in detail.
Roughness Scaling of Fracture Surfaces in Polycrystalline Materials
Authors: Seppäaläa Eira T. , Reed Bryan W. , Kumar Mukul , Minich Roger W. , Rudd Robert E. 
Published: April 2011

AbstractThe roughness scaling of fracture surfaces in two-dimensional grain boundary networks is stud- ied numerically. Grain boundary networks are created using a Metropolis method in order to mimic the triple junction distributions from experiments. Fracture surfaces through these grain boundary networks are predicted using a combinatorial optimization method of maximum flow — minimum cut type. We have preliminary results from system sizes up to N = 22500 grains suggesting that the roughness scaling of these surfaces follows a random elastic manifold scaling exponent ζ = 2/3. We propose a strong dependence between the energy needed to create a crack and the special boundary fraction. Also the special boundaries at the crack and elsewhere in the system can be tracked.
Direct Measurement of Impurity Segregation Concentration at Grain Boundaries for Polycrystalline Materials using EBSD and 3D Reconstruction of SEM images of Etch Grooves
Authors: Cornen Marilyne , Le Gall René 
Published: April 2011

AbstractImpurity segregation at grain boundaries in polycrystalline alloys is known to have a tremendous impact on the material properties such as mobility, cohesion.. But, direct measurement of grain boundary chemistry is quite complex and there are quite few results concerning polycrystals. In this paper we present an indirect method to measure segregation- misorientation dependence on polycrystalline Ni-S alloys using both EBSD and 3D reconstruction of etch grooves. Samples of Ni-S alloy (7.2 ppm at) have been annealed at different temperatures to get equilibrium segregation at grain boundaries. Then they have been etched near the transpassive potential to form etch grooves, whose geometry depends on the sulfur segregation level. Grain boundaries misorientation statistics and first results about the segregation-misorientation function are given here.
Preparation of SrS:Ce/ZnO Core-Shell Nanoparticles Using Reverse Micelle Method
Authors: Kusakari Yusuke , Ishizaki Shinji , Kobayashi Masakazu 
Published: April 2011

ABSTRACTSrS:Ce nanoparticles were prepared using a reverse micelle method and coated by ZnO. The mono-dispersed nanoparticles whose size was as small as 3nm were observed by transmission electron microscope (TEM) and dynamic light scattering (DLS) method. Optical properties of the core-shell SrS:Ce/ZnO nanoparticle was studied. UV-visible absorption and photoluminescence (PL) properties were measured and compared with those of SrS:Ce and SrS nanoparticles. Bright blue photoluminescence (around 440 nm) was observed from SrS:Ce at a room temperature when nanoparticles were excited using a Hg lamp. The PL peak intensity enhancement was observed after forming the ZnO shell. The optical absorption profile of nanoparticles was associated with the band edge feature of SrS. The coating of the SrS:Ce surface by ZnO has affected the electronic structure of SrS:Ce nanoparticles.
Near band-edge and excitonic behavior of GaAsN epilayers grown by Chemical Beam Epitaxy
Authors: Coaquira J. A. H , Bhusal L. , Zhu W. , Fotkatzikis A. , Pinault M.-A. , Litvinchuk A. P. , Freundlich A. 
Published: April 2011

ABSTRACTPhotoluminescence and absorption spectroscopy experiments were performed on as grown and thermally annealed GaAs1-xNx with nitrogen content in the range of 0.75–7.1%. At low temperature, the photoluminescence spectra exhibits two set of features: (i) a relatively broad peak at low energy and near to the vicinity of the predicted band gaps and (ii) a sharp excitonic feature at higher energy (about 100 meV for x>4%). Post growth thermal annealing processes systematically favor stronger excitonic emissions, and a notable intensity reduction of the deeper (defect related) luminescence. The low temperature binding energy of the higher energy excitonic peak is found to be consistent with the increase of the electronic effective masses. A careful examination of the data obtained in this work suggests that for higher nitrogen content (x>4%), the fundamental band gap of GaAsN is located at significantly higher energies than those commonly accepted for these alloys.
Good Temperature Performances of 870nm Resonant Cavity Light Emitting Diode (RCLED)
Authors: Laih Lih-Wen , Wu Yi-Hao , Laih Li-Hong , Hong Rong-Moo , Guo Hao-Chung , Yu Jung-Lung , Huang Yu-Hsiang , Chang Yi-An , Chang Ren-Jiun , Yang Chun-Hui , Wu I-Tsung 
Published: April 2011

ABSTRACTA high performance of wavelength 870nm resonant cavity LED (RCLED) was fabricated. The high performance of InGaAs/GaAs multiple quantum wells (MQWs) and distributed Bragg reflector (DBR) were employed to achieve the high transmission rate. Two devices A and B were fabricated in this paper. Device A has an offset of 10nm between active region gain and resonant gain, and device B without it. Due to the wavelength shift of active region gain is faster than that of DBR's resonant gain at higher temperature. Device A shows the better temperature performances than device B. A cutoff frequency of 60MHz, a low forward voltage of 1.6V, a output power of 1mW at 10mA and a output power temperature variation (ΔP/ΔT) of –0.02dBm/ °C with chip dimensions of 220um × 220um and 85um diameter emitting window are obtained.
Fabrication of ZnO Coated ZnS:Mn2+ Nanoparticles
Authors: Ishizaki Shinji , Kusakari Yusuke , Kobayashi Masakazu 
Published: April 2011

ABSTRACTThe fabrication of ZnO coated ZnS:Mn2+ nanoparticles were achieved using simple methods. ZnS:Mn2+ nanoparticles were prepared by a mechanical milling method. Coating of ZnO was then performed using a simple chemical method. Structural properties were evaluated by the X-ray powder diffraction (XRD) and the transmission electron microscope (TEM). Optical properties of the ZnO coated ZnS:Mn2+ nanoparticle were characterized by exciting the particle included solvent using an UV-LED (400 nm). Bright orange color fluorescence was observed, and the fluorescence intensity of ZnO coated ZnS:Mn2+ nanoparticles was enhanced as compared to uncoated ZnS:Mn2+ nanoparticles. The capping of the core surface has probably terminated surface defects of ZnS:Mn2+ nanoparticles, and resulted in the improved fluorescence intensity.
Structural investigation of InAs/InGaAs/InP nanostructures: origin and stability of nanowires.
Authors: Nieto L. , Gutiérrez H. R. , Bortoleto J. R. R. , Magalhães-Paniago R. , Cotta M. A. 
Published: April 2011

ABSTRACTIn this letter we present results on the growth of InAs nanowires (NW's) on InGaAs lattice-matched to (100) InP substrates by Chemical Beam Epitaxy. We observed that the nanostructure stability depends on the thickness of the InGaAs layer. This effect may result from two different conditions: the nanostructure strain field depth and/or compositional modulation in the buffer layer. Our investigation shows that anisotropic strain relaxation for nanowires grown on InGaAs is faster than for those grown on InP but the elastic energy in the nanostructures is no different from the InAs/InP case. These results suggest that the InAs strain relaxation does not depend significantly on the InGaAs buffer layer thickness. Nevertheless, transmission electron microscopy images show an additional stress field superimposed on that usually observed for the InAs nanostructures, which is attributed to compositional modulation in the ternary layer.
InAs Quantum Dots for Optoelectronic Device Applications
Authors: Stewart K. , Barik S. , Buda M. , Tan H. H. , Jagadish C. 
Published: April 2011

ABSTRACTIn this paper we discuss the growth of self-assembled InAs quantum dots (QDs) on both GaAs and InP substrates by low pressure Metal Organic Chemical Vapor Deposition. The influence of various growth parameters, such as the deposition time, the QD overlayer growth temperature, the V/III ratio and the group III and/or group V interdiffusion on QD formation are discussed and compared for the two systems. Stacking issues and preliminary results for an InAs/GaAs QD laser are also presented.
Correlation between Photoreflectance Spectra and Electrical Characteristics of InP/GaAsSb Double Heterojunction Bipolar Transistors
Authors: Sugiyama Hiroki , Oda Yasuhiro , Yokoyama Haruki , Kobayashi Takashi , Uchida Masahiro , Watanabe Noriyuki 
Published: April 2011

ABSTRACTWe report a photoreflectance (PR) characterization of InP/GaAsSb double-heterojunction bipolar transistor (DHBT) epitaxial wafers grown by metal-organic vapor-phase epitaxy (MOVPE). The origin of the Franz-Keldysh oscillations (FKOs) in the PR spectra was identified by step etching of the samples. FKOs from the InP emitter region were observed in the wafer with low recombination forward current at the emitter-base (E/B) heterojunction. In contrast, they did not appear when recombination current was dominant. The absence of the FKOs from the emitter indicates the high concentration of the recombination centers at the E/B heterojunction. We have also measured PR spectra from InAlP/GaAsSb/InP DHBT wafers. Pronounced FKOs from InAlP emitter reflect the suppression of recombination at E/B heterojunctions.
New Electroluminescence Spectrum from Co-doped ZnS:(Mn, Si) Films Prepared by Chemical Vapor Deposition with Laser Ablation
Authors: Ozawa Makoto , Satoh Tomomasa , Hirate Takashi 
Published: April 2011

ABSTRACTCo-doped ZnS:(Mn, Si) films were fabricated. The ZnS was synthesized by a low-pressure thermal chemical vapor deposition. Metal Zn vapor and H2S gas were used as the CVD-precursors. Mn and Si were doped using a laser ablation technique during the ZnS growth. A solid MnSi alloy (Mn:Si = 1:1) was used as the laser ablation target. The films were deposited at the range from 650°C to 750°C. At the deposition temperature of 650°C, only a EL emission peak at 585 nm same as conventional ZnS:Mn films appeared, i.e., the Si co-doping had no effects on the EL spectrum. At the deposition temperature of 700°C, the Si co-doping to ZnS:Mn film caused the shift of the EL emission peak at 585 nm to shorter wavelength by 15 nm and provided new EL emission at 760 nm. The film deposited at 750°C exhibited new UV and blue EL emissions at 390 nm and 450 nm, respectively, although the host material of the film differed from usual ZnS.
Growth and Characterization of bulk GaN by Ga Vapor Transport
Authors: Konkapaka Phanikumar , Wu Huaqiang , Makarov Yuri , Spencer Michael G. 
Published: April 2011

ABSTRACTBulk GaN crystals of dimensions 8.5 mm × 8.5 mm were grown at growth rates greater than 200μm/hr using Gallium Vapor Transport technique. GaN powder and Ammonia were used as the precursors for growing bulk GaN. Nitrogen is used as the carrier gas to transport the Ga vapor that was obtained from the decomposition of GaN powder. During the process, the source GaN powder was kept at 1155°C and the seed at 1180°C. Using this process, it was possible to achieve growth rates of above 200 microns/hr. The GaN layers thus obtained were characterized using X-Ray diffraction [XRD], scanning electron microscopy [SEM], and atomic force microscopy [AFM]. X-ray diffraction patterns showed that the grown GaN layers are single crystals oriented along c direction. AFM studies indicated that the dominant growth mode was dislocation mediated spiral growth. Electrical and Optical characterization were also performed on these samples. Hall mobility measurements indicated a mobility of 550 cm2/V.s and a carrier concentration of 6.67 × 1018/cm3