bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observation and Study of Wavelength Dependence of The Open-Circuit Voltage In a-Si:H BASED p-i-n SOLAR Cells
Authors: Gorn M. , Kniffler N. , Winterling G. 
Published: March 2011

ABSTRACTThe spectral dependence of Voc is studied in a-Si:H based p-i-n junctions by using chopped monochromatic light. A dispersion ΔVoc = Voc(blue) - Voc(red) is observed which depends systematically on a low level doping of the central layer. While ΔVoc is largest and positive in phosphorous doped cells it is negative in boron doped cells. Voc is found to be enhanced by an additional white bias light.The dispersion data are discussed by considering the contributions to Voc arising from drift in an inhomogeneous field and from carrier diffusion.
Cowparison Studies of Hydrogenated Amorphous Silicon Films Prepared From Silane-Hydrogen and Silmne-Helium Mixtures
Authors: Patel R. I. , Olsen D. J. , Shirck J. R. , Tran N. T. 
Published: March 2011

ABSTRACTHydrogenated amorphous silicon films were produced from silane/hydrogen and silane/helium gas mixtures by RF glow discharge. We examined the optical and electrical properties of films produced with these gas mixtures, at various RF power levels and silane fractions. Film quality was analyzed by measuring the dark and photoconductivity, optical band gap, and activation energy. Optical emission spectroscopy was also used as a diagnostic tool for studying the plasma during glow discharge depositions. Experimental results indicate that amorphous silicon films made from silane/helium mixtures exhibit improved optoelectronic properties, higher deposition rates, and higher emission intensity ratios (ISiH/IH) as compared to films produced from silane/hydrogen mixtures. In preparing films from silane/helium mixtures, the onset of dust/powder formation occurs at considerably higher RF powers as compared to silane/hydrogen, thus making this approach an attractive commercial option for depositing films at high rates.
Stability and Efficiency in Amorphous Tandem Solar Cells
Authors: Galluzzi F. , Conte G. , Angelis L. De , Peruzzi R. 
Published: March 2011

ABSTRACTTheoretical evaluation of stability and efficiency of two-junction two-terminal amorphous tandem solar cells is performed using an analytical model which takes into account not only optical characteristics and transport properties but also photodegradation effects due to dangling bond formation under light exposure.Requirements for material quality and device design are particularly investigated.
VLSI Processing of Amorphous Silicon Alloy P-I-N Diodes For Active Matrix Applications
Authors: McGill J. , Cannella V. , Yaniv Z. , Day P. , Vijan M. 
Published: March 2011

ABSTRACTA number of new amorphous silicon alloy microelectronic devices, including LCD active matrix displays, linear image sensors, and thin film multilayer computer memories, have been developed in our company. These applications rely heavily on the quality of the intrinsic semiconductor as well as its ability to withstand the many processing steps used in a modern photolithographic process. In this paper, we present electrical data on amorphous silicon alloy p-i-n diodes after such a process. These devices have an active area of 20μm × 20μm defined using standard photolithographic techniques and etched using a dry etch process. These diodes are characterized by ideality factors (n) of 1.4 and extrapolated reverse saturation current densities of 1013A/cm2h. The diodes exhibit nearly 10 orders of magnitude rectification at ± 3V and the reverse bias current density remains below 10-8 A/cm2 for reverse bias voltages of -15V. In pulsed forward bias, these diodes can be operated at current densities greater than 300A/cm2. Thin film amorphous silicon diodes moreover have the advantage that varying the thickness of the intrinsic layer allows the optimization of parameters such as the capacitance per unit area, the reverse bias current density and the forward bias conductance per unit area. We find that these devices are fully compatible with state of the art VLSI processing techniques and are suitable for applications in integrated circuit structures, for example rectification devices in microelectronic arrays and isolation devices in display matrices.
Short Channel Length Planar Tft's Using Amorphous Silicon Alloys
Authors: Yang M. , Yaniv Z. , Vijan M. , Cannella V. 
Published: March 2011

ABSTRACTThere is a rapid growth of interest in the application of amorphous silicon alloy thin film devices to large area microelectronic circuits. Increased current levels are a constant goal since gains in device current result in proportional gains in power and speed. Mobility limitations in amorphous silicon thin film transistors have directed interest toward short conduction channel devices to achieve higher current levels; furthermore, compatibility with large area processing makes photolithography with 10μm feature size very attractive. Consequently, innovative techniques, which define channel lengths by processing parameters rather than by mask feature size are necessary. Previous work has applied such techniques to vertical structure TFT's which define channel lengths by the vertical height of deposited layers. Here, we report on a technique which achieves short channel lengths in planar structures using etching parameters to define short channel lengths. Amorphous silicon alloy TFTs have been fabricated with channel lengths of ≈2μm which reach currents of lma. These techniques broaden the range of application of amorphous silicon alloy TFTs by providing devices capable of operating at higher currents and higher speeds.
Application of Two-Step Deposition Method To Ultra-Thin a-Si FETs
Authors: Katoh Y. , Sugiura O. , Takeuchi Y. , Uchida Y. , Matsumura M. 
Published: March 2011

ABSTRACTTwo-step deposition method for fabricating ultra-thin a-Si FETs has been investigated theoretically and experimentally. Theoretical relation between field-effect mobility and a-Si layer thickness agreed qualitatively with the experimental results. The mobility of the 15nm-thick FET was drastically improved by an application of the two-step deposition method.
Back-To-Back Amorphous Silicon Diodes For Driving Lc Displays
Authors: Dresner Joseph 
Published: March 2011

ABSTRACTThis paper describes the preparation and electrical characteristics of a-Si:H p-i-n-i-p and n-i-p-i-n thin film diodes suitable for driving monochrome liquid crystal displays with more than 500 lines. The symmetrical current-voltage curves in the reverse breakdown regime can ge described by i=i exp (E/Eo) where E ≃9×104 V/cm. In the range 20–125°C, the current is thermally activated with an energy of 0.25eV. The response time to applied voltage pulses is ≤ 10 us. The stability of the electrical characteristics is adequate for at least 104 hours of operation in an liquid crystal display.Electrical characteristics indicate that the reverse breakdown current is a tunneling current injected into the i-layer and that electrons are likely to be dominant.
Optical Response of As2 S3: Melt Quenched Versus Spin Casted Materials
Authors: Hammam M. , Santiago J. J. 
Published: March 2011

ABSTRACTThe transmittance spectra of amorphous As2S3 films prepared by two different techniques, namely spin coating and quenched from the melt were investigated. All measurements were done at room temperature in the energy range from 1.2 to 3.8 eV. The spin casted material was prepared by dissolving powdered stoichiometric arsenic trisulfide in amines and amides, the resulting solution spinned on an oxide glass substrate and baked to remove the volatiles. A typical resulting film was a few micrometers thick and microstructure free as characterized under an optical microscope. The quenched material was prepared by melting a stoichiometric mixture of the reactants in an evacuated and sealed ampoule and alloying at 1100°K for 15 hrs. The melt was subsequently quenched in air to obtain vitreous materials. The transmittance spectra of both types of samples was measured and from the spectra the refractive index dispersion, film thickness and absorption coefficient were obtained. A considerable difference between the optical constants of the spin casted samples and thermally evaporated ones was found. This was attributed to the incorporation of carbon and hydrogen in the amine salt alkyl group formed when dissolving the chalcogenide material.
Intrinsic Gettering of Iron in Silicon: A Quantitative Study
Authors: Colas Etienne G. , Weber E.R. , Hahn S. 
Published: March 2011

AbstractIntrinsic gettering of iron in silicon has been studied with a novel approach that involved the combination of two complementary techniques. Electron Paramagnetic Resonance (EPR) was used to determine the concentration of interstitial iron atoms which are electrically active in the silicon matrix. A systematic comparison of the effect of various oxygen precipitates of well defined morphologies on the solubility of iron was performed. A surprising result was found for bulk samples containing oxygen precipitates obtained after low temperature heat treatments (700ºC): the solubility of iron was reduced byalmost two orders of magnitude from the values obtained in untreated Cz silicon samples or in samples containing oxygen precipitates obtained at high temperature (1150ºC). The practical importance of this new result was demonstrated by a series of iron concentration measurements after various gettering and high temperature re-heating treatments.Transmission Electron Microscopy (TEM) was used in order to confirm the proposed mechanism of formation of a new phase, different from FeSi2 in the silicon matrix. This new phase is assumed to limit the possible electrically active metallic content by acting as a boundary phase in quasi-equilibrium with interstitial iron atoms. Evidence ofthe formation of Fe2SiO4 was found in wafers that had been oxygenimplanted and subsequently subjected to similar precipitation and diffusion treatments than those performed with the bulk samples.These findings suggest the possibility of dramatic improvements in the efficiency and the stability of the gettering process.
Regrowth of Implanted–Amorphous Si
Authors: Ling P. , Wu N.R. , Washburn J. 
Published: March 2011

AbstractA two dimensional model of nucleation and growth is described which is consistent with the following experimental phenomena observed in the regrowth of ion-implanted silicon: (1) Substrate orientation effect on regrowth kinetics. (2) Impurity effects on regrowth kinetics. (3) The activation energy dependence of regrowth rate. (4) Impurity redistribution and supersaturation effect.
Dopant Diffusion From Ion- Implanted Tasi2
Authors: Gierishch H. , Neppl F. , Frenzel E. , Eichinger P. , Hieber K. 
Published: March 2011

AbstractA SIMS analysis of As-, B- and P- diffusion across the TaSi2/si interface into mono- Si was carried out together with an electrical characterization of the resulting structures. In the temperature range 900°C T 1000°C all three types of dopants readily diffused into Si without drastic segregation effects when appropriate interface cleaning was applied. This implies a variety of applications. In particular, very shallow diffusion regions were obtained in the mono Si underneath the implanted Tasi2 for As as well as for B and P, even at relatively long annealing times sometimes needed for subsequent process steps.
On the Mechanism of Intrinsic Gettering by Butterfly-Type Defects in Silicon
Authors: Ueda O. , Nauka K. , Lagowski J. , Gatos H.C. 
Published: March 2011

AbstractWe have recently found that a very effective intrinsic gettering of metal contaminants in silicon can be realized via interaction of native defects. This process makes it possible to extend intrinsic gettering of crystals with low or virtually zero oxygen concentration. Transmission electron microscopy and energy dispersive x-ray spectroscopy were used to identify the microscopic structure of the gettering centers in oxygen-free silicon. These centers exhibited butterfly-type shape and they consisted of the interstitial type extended dislocation loops of 0.1 to 0.7 μm diameter. Small precipitates (3-15 nm diameter) of metal (Cu, Ni, Fe) silicides were found inside the dislocation loops and/or on the dislocation lines. The origin of butterfly-type gettering centers will be discussed in terms of the intrinsic gettering model involving lattice supersaturation with silicon self-interstitials as a driving force for their complexing and subsequent formation of dislocation loops and precipitates which immobilize metal contaminants.
Schottky Barrier Heights of Refractory Metals on Silicon
Authors: Aboelfotoh M. O. 
Published: March 2011

AbstractMeasurements of Schottky-barrier heights in the temperature range 175-295 K for refractory metal-silicon and corresponding silicide-silicon interfaces are presented. Refractory metal silicide formation is shown to have only a small effect on the barrier height. The n-type and p-type barrier heights for both the metal and the reacted silicide phase are shown to decrease with increasing temperature with the stun equal, within the experimental accuracy, to the indirect energy gap of silicon at any measured temperature. These results indicate that the temperature dependence of the barrier heights is mainly due to that of the indirect energy gap in the silicon.
Comparison of Electromigration Induced Resistance Changes in Multilayer Al-Si/Ti and Al-Si/Ta Interconnects
Authors: Finetti M. , Suni I. , Desanti G. , Bacci L. , Caprile C. 
Published: March 2011

AbstractWe have applied a temperature-ramp resistance analysis to investigate electromigration effects in unpassivated Al-Si/Ta multilayer structures. The results are compared to the behaviour previously observed in Al-Si/Ti interconnects. For comparison, single layer Al-Si metallizations were also studied.
Comparison of Kinetics of TiSi2 Formation on Si(100) and Si(111)
Authors: Pico C. A. , Tran N. C. , Jacobs J. R. , Lagally M. G. 
Published: March 2011

AbstractRefractory-metal silicides are currently receiving widespread attention because of their usefulness as interconnects in VLSI devices. Potentially the most important of these silicides is TiSi2. TiSi2 offers a sharp stable interface, a high process-compatible eutectic temperature, and the lowest resistivity of all refractory-metal silicides. Much of the previous work on TiSi2 [1-8] has been directed towards the understanding of the kinetics of silicide formation in order to optimize these electrical and interfacial properties. One parameter that may affect the silicide formation is substrate orientation [9]. We have compared the kinetics of formation of TiSi2 for Ti deposited onto p-type 10Ω-cm Si(100) and Si(111). All process parameters except substrate orientation were identical. 2800Å of Ti was electron-beam evaporated at a rate of 20Å/s and a background pressure of 9×10−8 torr onto chemically cleaned (HNO3, HF, rinse) Si substrates and subsequently annealed at temperatures between 470°C and 700°C in evacuated sealed quartz tubes. A turbopumped vacuum system was used to evacuate the quartz tube before sealing. A Ti getter was independently heated to remove remaining background contaminants prior to annealing.
The Effect of HCl on Silicon Point Defect Formation During Thermal Oxidatign of (100) Float Zone Silicon Wafers: A Theoretical Analysis
Authors: Oh Seajin , Tiller W.A. , Hahin Soo Kap 
Published: March 2011

AbstractThe effect of HCl in an oxidizing ambient on Si interstitial formation during oxidation has been studied by the buried marker diffusion technique. Adding HCl reduces the self-interstitial flux generated at the oxidation front but it does not completely eliminate it. A uniform blocking layer model predicts fairly well the Cl effect on self-interstitial generation during the thermal oxidation. By reducing the rigidity of the SiO2, Cl incorporation into the SiO2 is strongly proposed to alter the Si interstitial partition coefficient at the interface.
Modeling Dopant Redistribution During Rapid Thermal Annealing
Authors: Chan Archie Y.C. 
Published: March 2011

AbstractThe diffusion of ion-implanted dopants in silicon during rapid thermal annealing is modeled using the finite difference method.The change in impurity profile for an initial Pearson IV boron implant is negligible(less than 1 % change in junction depth) when the peak annealing temperature(TP ) is less than 1050 °C and its duration is shorter than 20 seconds. The dopant redistribution becomes significant(greater than 25 % change in junction depth) when Tp is greater than 1200 °C and its duration is longer than 40 seconds.The heatup and cooldown portions of the transient annealing cycle are found to have little effect on dopant redistribution provided that their rates are higher than 120 °C per second.
Laser Activated Glass Flow Modeling
Authors: Aronowit Sheldon , Delfino Michelangelo 
Published: March 2011

AbstractLaser induced flow of phosphosilicate glass, where the glass is a member of a multi-layer structure, was modeled with a one-dimensional coupled set of heat conduction and generation equations; the conventional approach was modified for explicit inclusion of non-ideal interfacial regions. There were no restrictions on the number or nature of material layers. Modeled behavior for 0.7 μm or 1 μm thick glass covering Al, or Si02, or Si agreed with observation; aluminum fusion accompanied by minimal glass flow when the AZ layer was covered by 0.7 μm glass was predicted and observed for the experimental laser pulse, as an example. Analysis also exposed the characteristics for successful laser generated glass flow; a rectangular pulse shape will permit the greatest control over the laser induced flow as well as provide the largest window for producing the desired flow while minimizing the effect on other material regions. Finally, experimental results with CW laser induced flow support the conclusion that the modeling successfully bridges four orders of magnitude in the thermal flux regime.
Electrical Characteristics of High Pressure Nitrided Oxides
Authors: Ellul J.P. , Tay S.P. , Kalnitsky A. 
Published: March 2011

AbstractIn this paper, we present preliminary electrical characteristics of as-grown and NH3-nitrided thin gate and polysilicon oxides. Material characteristics are discussed in terms of ammonia concentration and nitridation temperature and pressure. Dielectric thicknesses obtained by ellipsometry, by Auger analysis and by capacitance-voltage measurements are compared. Electrical breakdown statistics for 10 atm and 1 atm pressure nitrided oxides are compared to as-grown thermal oxides.
High Quality 100 Å Thermal Oxide
Authors: Nguyen Thao N. , Quinlan Dawn L. 
Published: March 2011

AbstractThe growth of high quality 100 Å thermal oxide is investigated. Different growth conditions including oxidation temperature, oxidation rate, and gas ambient are explored and they all produce good oxides. However, it will be demonstrated that the best oxide with defect density as low as 0.2cm−2, breakdown field ≃ 12 MV/cm and good reproducibility is grown with low temperature (800°C) low rate oxidation in dry oxygen. The midgap interface trap density of this oxide is ∼ 2.0 × 1010eV−1cm−2 obtained from high-frequency and quasi-static C-V data. A model based on physical mechanisms controlling the kinetics of thin oxide growth is developed to understand how the quality of thin oxide is affected by growth conditions and to explain why the low temperature oxidation in dry oxygen yields the best film.
Growth of Heteroepitaxial Lead Chalcogenide Infrared Detector Arrays on Fluoride Coveredsilicon Substrates
Authors: Zogg H. , Vogt W. , Melchior H. 
Published: March 2011

AbstractComposition graded buffer layers of group Ila fluorides allow the heteroepitaxial growthof device quality narrow gap lead chalcogenides onto Si. Mechanical stresses in the layers are almost completely relaxed at room temperature despite large thermal expansion mismatches. Photovoltaic infrared sensors with up to about 9.5 um cut—off wavelengths and which operate at or near the 300K background noise limit have been fabricated in such PbTe and (Pb,Sn)Se on Si structures.Furthermore, epitaxial graded fluoride buffers seem to be suited to connect other semiconductors with even large lattice mismatches. Initial heteroepitaxial growth of CdTe on fluoride/Si(lll) substrates (mismatch 20%) supports such more general applications.
Application of Sans to Ceramic Characterization
Authors: Frase K. G. , Hardman-Rhyne K. A. , Berk N. F. 
Published: March 2011

ABSTRACTTraditionally, small angle neutron scattering (SANS) has been used to study dilute concentrations of defects 1 -100 nm in size. Recent extensions of the scattering theory have allowed the expansion of the technique to include larger sizes through the use of multiple scattering. With multiple small angle neutron scattering, defects (pores, microcracks, precipitates) up to 10 μm in size can be studied. SANS is inherently a non-destructive, bulk probe of microstructure, with wide applications in the characterization of materials.A number of studies of ceramic materials using multiple and traditional (single particle diffraction) small angle neutron scattering will be discussed. The emphasis will be on the strength of the technique in the characterization of materials. Particular examples will include: the assessment of pore size distributions in spinel compacts as a function of sintering and agglomeration, the characterization of primary and secondary particle sizes in precipitated aggregates, and the determination of microporosity in MDF cements.
Microstructural Studies of Transparent Silica Gels and Aerogels
Authors: Tewari Param H. , Hunt Arlon J. , Lofftus K. D. , Lieber J. G. 
Published: March 2011

ABSTRACTTransmission electron microscopy, spectroscopy, light scattering and surface area measurements have been used to characterize the microstructural details of transparent silica aerogels. Light scattering intensity measurements have also been used to differentiate acid and base catalyzed hydrolysis and condensation reaction kinetics of Si(OC2H5)4. A plot of logarithm of the light scattering intensity vs. logarithm of time diring gelation gives distinctly different slopes for acid and base catalyzed systems (6 for acid and 2 for base). These slopes for the two systems can be explained on the basis of the point of zero charge of silica and the resulting interactions of the uncharged and charged particles in the systems.
Fractal Aspects of Ceramic Synthesis
Authors: Schaefer Dale W. , Keefer Keith D. 
Published: March 2011

ABSTRACTThe concept of fractal geometry is used to describe the structure of silica polymers, colloidal aggregates, and critical systems. We illustrate the interpretation of scattering curves (X-ray, neutron and light) for fractal systems, and review simple growth models which generate fractal structures. We describe the polymerization of silica under various conditions and demonstrate that, depending on chemical conditions, polymerization maps onto simple fractal growth processes. The key factors which control growth are monomer-cluster vs. cluster-cluster growth, and reaction-limited vs. diffusion-limited growth.
Particle Compaction with Alternating Electric Fields: The Effects of Electrode Geometry
Authors: Hurd Alan J. 
Published: March 2011

ABSTRACTA technique for inducing ordered, close-packed arrangements of various symmetries among colloidal particles is discussed. An external alternating electric field applied to the colloid induces dipole interactions of variable strength by polarizing either the dielectric material of the particles or their electrostatic double layers. Ordering in various symmetries can be obtained by switching the field rapidly between pairs of electrodes, thereby changing the orientation of the induced dipoles. A small dc bias serves to deposit and compact the aligned particles.