bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrochemical Preparation of Silver Selenide Films and Nanowires from Aqueous Solutions
Authors: Chen Ruizhi , Xu Dongsheng , Zhou Weilie , Tung Le Duc , Spinu Leonard , Guo Guolin 
Published: June 2019

AbstractBoth thin films and nanowires of silver selenide were synthesized by electrodeposition from an aqueous acid electrolyte containing silver ion complexed with SCN- and selenium dioxide at room temperature. Orthorhombic Ag2Se films with Ag slightly in excess were obtained. After annealing in argon atmosphere, the films are highly (002) oriented. A positive transverse magnetoresistance of about 20–25% at T = 5 K, and 10–13% at T = 300 K, in fields of H=50 kOe were observed in the electrodeposited films. Furthermore, silver selenide nanowires were synthesized from the same aqueous system by electrodeposition in porous anodic alumina templates. X-ray diffraction (XRD), Transmission electron microscopy (TEM), and Energy dispersive absorption X-ray (EDAX) characterization results showed that the nanowires are highly crystalline with (002) growth direction after annealing. In addition, the atomic ratio of Ag/Se in the films and the nanowire samples can be controlled from about 3.0 to 2.1 by adjusting the concentration of AgI and SeIV source and the deposition potential.
Ti-Island-Catalyzed Si Nanowire Growth by Gas-Source MBE: Morphology and Twinning
Authors: Tang Qiang , Liu Xian , Kamins Theodore I. , Solomon Glenn S. , Harris James S. 
Published: June 2019

AbstractSilicon nanowires catalyzed by Ti islands have been grown by molecular beam epitaxy (MBE) using Si2H6 as the gas source and characterized by in situ reflection high-energy electron diffraction (RHEED), scanning-electron microscopy (SEM) and transmission-electron microscopy (TEM). Approximately one monolayer of Ti was deposited on Si(001) wafers, which, during annealing, reacted with silicon and formed TiSi2 islands. After annealing, but before Si growth, the stoichiometric TiSi2 (C49) phase was observed with RHEED.The silicon nanowires are typically between 20 and 40 nanometers in diameter and several hundred nanometers long. The nanowires changed their growth direction several times during growth, resulting in complex RHEED patterns, which can be matched very well by simulated RHEED patterns calculated assuming that the nanowires change their direction by twinning along (111) planes. RHEED patterns of epitaxial silicon nanowires, first-order twinned nanowires (twinned relative to the substrate orientation), second-order twinned nanowires (twinned relative to the first-order twin), and TiSi2 were observed.
Performance Comparisons of Abrasive Containing and Abrasive Free Slurries for Copper Low-k CMP
Authors: Nguyen John , Martin Gerald , Carpio Ron , Grief Malcolm , Joshi Somit 
Published: June 2019

AbstractThe commercially available abrasive containing slurries for copper CMP have shown some advantages in high removal rates, low friction at low down force, and minimal to no copper residues, regardless of the polisher architecture, either rotary, orbital, or linear polishing. However, the abrasive containing slurries have some disadvantages such as high dishing and erosion with more micro-scratches due to the presence of abrasives. In contrast, the abrasive free polishing slurry has lower removal rate, and seems to be sensitive to polishing architecture, but it has good planarization, low topography, less micro-scratches, and most importantly is insensitive to over-polish.At this stage, the best results for copper CMP are being achieved by the use of the multi-step and multi-slurry process in which copper is polished first, and barrier layers are polished with a different set of consumables. The intent of this paper is to focus on the first step, the copper removal step, and to compare different approaches for this first step; namely, the use of slurries containing abrasives with slurries that are free of abrasives on the orbital polisher. The combined process with low percent solid and small-sized abrasives for the bulk copper removal step and abrasive free polishing (AFP) slurry for the residual copper removal step on an orbital polisher has produced a very robust process window with excellent results including low topography, low erosion, insensitivity to over-polish and low cost of ownership.
New Slurry Formulation for Copper-CMP Process in a Damascene Integration Scheme
Authors: Terzieva Valentina L. , Sijmus Bram M. , Meuris Marc A. , Puppe Lothar , Passing Gerd 
Published: June 2019

AbstractIn this work novel slurries both for copper and tantalum nitride removal were developed. In the first step the Cu bulk is removed, by using high selective slurry, which stops on the underlying TaN barrier. The selectivity of Cu vs. TaN achieved with this slurry is larger than 1/100. High selective second step slurry is further introduced for removing the barrier material. In the present work data concerning dishing and erosion will be presented as a function of line width and pattern density across the wafer. Electrical yield measurements on shorts and opens of meander-fork structures will be discussed.
Analysis of Local Planarization with Polishing Time, Film Thickness, Chemical Non-Uniformity, Line Density, Line Width, and Pad Relaxation Property
Authors: Bian Jinru , Quanci John 
Published: June 2019

AbstractTheoretical chemical mechanical polishing local planarization models as a function of polishing time and film removal are reviewed, and re-derived in a systematic and correlative way. The derived models employ pad viscoelastic and relaxation properties to explain the experimental phenomena that step height local planarization is an exponential function of line width at the same line density, and also account for the affect of pattern density and polishing of two different materials at the same time on step height planarization.
Study of Defect Generated During Cu/Black Diamond CMP Process
Authors: Wu Shaoyu , Li Ning , Kang J. M. , Lam T. W. M. , Lin B. , Selvaraj T. , Zhao S. P. , Kumar R. , Foo P. D. 
Published: June 2019

AbstractBlack Diamond (BD) is gaining popularity as a low k dielectric for copper/low k integration. However, because of lower hardness and more hydrophobic in nature of BD film surface comparing with those of the conventional oxide, some specific defects appear during CMP process of Cu/BD patterned wafers. In this study, the patterned wafer inspection systems, AIT II, and SEM review station are used to review and to classify such defects generated from CMP process. Using conventional Cu/Oxide CMP process, the percentage of these specific defects from Cu/BD CMP is typically more than 60 of total defect count. By modifying the composition of slurry with new additives and optimization of polishing and cleaning parameters, the total defect count can be reduced by 80%, in which the amount of specific defects is less than 5% of total defect count.
On the Role of Surface Diffusion and Its Relation to the Hydrogen Incorporation During Hydrogenated Amorphous Silicon Growth
Authors: Smets A.H.M. , Kessels W.M.M. , van de Sanden M.C.M. 
Published: June 2019

AbstractThe incorporation of hydrogen in vacancies and at void surfaces during hydrogenated amorphous silicon growth from a remote expanding thermal plasma (ETP) is systematically studied by variation of the mass growth flux Γa-Si:H and substrate temperatureTsub. An evident relation between the void incorporation and the growth parameters Γa-Si:H andTsubhas been observed. We speculate on a possible relation with the surface diffusion processes during deposition. An activation energy for surface diffusion during a-Si:H growth of 0.8-1.1 eV is obtained using this assertion, similar to the activation energy deduced from surface roughness evolution studies. For compact films hydrogen is predominantly present at vacancies, and a possible relation with the hydrogen removal mechanism during deposition is discussed.
Hydrosilylation of Silicon Surfaces: Crystalline versus Amorphous
Authors: Lehner Andrea , Steinhoff Georg , Brandt Martin S. , Eickhoff Martin 
Published: June 2019

AbstractUsing thermally induced hydrosilylation, organic molecules were covalently bonded to H-terminated crystalline silicon (111) and hydrogenated amorphous silicon (a-Si:H) surfaces. The resulting chemical surface structure was analyzed by X-ray photoelectron spectroscopy (XPS) and compared to that of silicon surfaces covered by a native oxide or terminated with hydrogen. For both kinds of substrates, the presence of oxygen on the surface is found to hinder the hydrosilylation reaction. Stable H-termination as a starting point for a successful hydrosilylation can be obtained on a-Si:H surfaces with much less technological effort than on crystalline silicon surfaces. Photoconductivity measurements of the different a-Si:H surfaces at low intensity of illumination (monomolecular recombination regime) indicate that the hydrosilylated surface has less defects than the H-terminated surfaces or surfaces covered with native oxide. Spin-dependent photoconductivity measurements identify the dominant paramagnetic defect at the hydrosilylated a-Si:H surface to be the silicon dangling bond.
Atomistic Character of Nanocrystalline and Mixed Phase Silicon
Authors: Biswas R. , Pan B. C. 
Published: June 2019

AbstractMaterials grown close to the phase boundary of amorphous and microcrystalline growth have the best electronic properties for solar cells. Systematic molecular dynamics methods have generated such nano-crystalline silicon, consisting of a mixed phase of nano-crystallites in an amorphous matrix, using an embedding method. An excess density of H resides on the surface of the nanocrystallites. The structure of this heterogeneous phase will be characterized by atomic distribution functions and structure factors. The electronic band structure of smaller models of nanocrystalline silicon reveals no midgap states and is similar to a-Si:H. There is a highly strained region surrounding the crystallites. The presence of localized strain region may increase the stability of the material.
Evidence For Trap-Conversion Induced Instability In Amorphous Silicon
Authors: Dalal Vikram L. , Sharma Puneet , Aziz Abdul 
Published: June 2019

AbstractIt has been shown recently that there are two distinct types of recovery during annealing of amorphous Silicon after degradation due to light soaking. It has been postulated that the two different kinetics of annealing point to the existence of two different types of states, with perhaps one state being charged dangling bonds and the other state being neutral dangling bonds. To see if two kinds of states exist, in this paper, we study the kinetics of degradation within the first 100 seconds, and also study the entire absorption curve at all degradation times. An analytical model is derived for early time degradation based on the conversion of a D- state into a neutral dangling band by absorption of a light generated ( the trap-to-dangling bond conversion model of Adler) and the experimental data of degradation versus light intensity fit the predictions of the model very well. The model also predicts that the Adler-type negatively charged defect states, which have a negative correlation energy, upon conversion will transform into Do states at a higher energy, and therefore, there should be a decrease in absorption corresponding to states closer to the valence band, and an increase in absorption corresponding to states near the mid-gap. For the films where such D- states are deliberately introduced by using a small oxygen (a donor atom) leak, we see strong evidence for such a behavior in absorption, with a decrease in the 1.3-1.4 eV photon energy range, and an increase in the 1.1 eV photon energy range. The increase in Do corresponds well with the decrease in photo-conductivity, even at the earliest times.
Properties of High Quality p-Type Micro-Crystalline-Si Prepared by Cat-CVD
Authors: Matsumura Hideki , Katouno Kouichi , Itoh Masaya , Masuda Atsushi 
Published: June 2019

AbstractProperties of p-type μc-Si prepared by Cat-CVD (Catalytic Chemical Vapor Deposition), often called Hot-Wire CVD, are studied for possible application to window layer of a-Si solar cells. Electrical, structural and optical properties are investigated. It is concluded that Cat-CVD p-type μc-Si is a suitable material as a window layer for Cat-CVD a-Si solar cells.
Microstructure and Optical Functions of Transparent Conductors and their Impact on Collection in Amorphous Silicon Solar Cells
Authors: Ferreira G. M. , A. ChiChen , Ferlauto S. , Rovira P. I. , An Ilsin , Wronski C.R. , Collins R. W. , Ganguly G. , Kwak Joong Hwan , Lim Koeng Su 
Published: June 2019

AbstractWe have developed new procedures for determining the microstructure as well as the index of refraction and extinction coefficient spectra {n(E),k(E)} for textured SnO2thin films on glass used as the top contact layers and superstrate for amorphous silicon (a-Si:H) p-i-n solar cells. These procedures combine (i) multichannel Mueller matrix spectroscopy using a dual rotating-compensator spectroscopic ellipsometer in reflection from the surface of the SnO2, a measurement that is most sensitive to microstructure andn(E), and (ii) transmission spectroscopy through a double-thick SnO2sandwich contacted with index-matching fluid, a measurement that is most sensitive tok(E). An important optical loss in a-Si:H p-i-n solar cells is reflection from the SnO2/p-layer interface. In this paper, we characterize this optical loss through modeling the solar cell optical quantum efficiency and demonstrate the extent to which microscopic roughness at this interface can serve as an anti-reflection layer for enhanced collection.
Field-Assisted Germanium Induced Crystallization of Amorphous Silicon
Authors: Derakhshandeh J. , Mohajerzadeh S. , Golshani N. , Soleimani E. Asl , Robertson M.D. 
Published: June 2019

AbstractA field-assisted germanium-induced crystallization of amorphous silicon on glass is reported at temperatures below 500°C. Silicon films with a thickness of 0.1um are covered with 500Å of germanium as the seed of crystallization. Applying an electric field enhances the growth from both cathode and anode sides. XRD, SEM and TEM analyses have been used to study the crystallinity of the samples which have been treated under different annealing conditions, all confirming the polycrystalline nature of the annealed silicon films. The value of the applied voltage plays a crucial role in the crystalline quality of Si layers. While samples treated without an external voltage are not polycrystalline, an electric voltage of 10 V applied for a 1cm separation between anode and cathode, seems suitable for achieving good poly-crystalline Si layers. The size of grains varies between 0.1 and 0.2μm, as observed using SEM.
A Simple Lateral Grain Growth of Poly-Si by Single Excimer Laser Crystallization of Amorphous Silicon Film Deposited on Polygon Shaped Trench
Authors: Jung Sang-Hoon , Kang Su-Hyuk , Shin Hee-Sun , Han Min-Koo 
Published: June 2019

AbstractA simple lateral grain growth of polysilicon employing single excimer laser irradiation is proposed. In order to increase the size of silicon grain and to control the location of the large lateral grain, the oxide trench is employed under the amorphous silicon film in the proposed method. The proposed oxide trench, which is shaped like a triangle or a polygon with an acute angle, induces temperature gradient on the molten silicon film during the solidification. It was verified by SEM that about 2 μm-long silicon grains are successfully achieved near the oxide trench edge and the locations of lateral grains are controlled by the angular points of the diagram.
Anomalous behaviour of stain etched porous silicon photoluminescence
Authors: Guerrero-Lemus Ricardo , Ben-Hander Fathi A. , Hernández-Rodríguez Cecilio , Martínez-Duart José M. 
Published: June 2019

AbstractIn this work we present a comparative study of porous silicon (PS) photoluminescence for samples stain etched and electrochemically etched. The etching parameters for both types of samples have been adjusted to obtain similar porous structures. The photoluminescence spectra have been obtained varying the excitation energy between 2.48 and 3.54 eV. The variation of the excitation energy produces differences in the evolution of the emission energy maximum between both types of PS. This behaviour is attributable to the differences in oxidation level in the porous structure. Also it has been established a higher concentration of luminescent centers for stain etched PS.
Development of Vertically Integrated Imaging and Particle Sensors
Authors: Wyrsch N. , Miazza C. , Dunand S. , Shah A. , Blanc N. , Kaufmann R. , Cavalier L. , Anelli G. , Despeisse M. , Jarron P. , Moraes D. , Sirvent A. G. , Dissertori G. , Viertel G. 
Published: June 2019

AbstractIntegrated imaging and particle sensors have been developed using thin-film on ASIC technology. For this purpose, hydrogenated amorphous silicon diodes, in various configurations, have been optimized for imaging and direct particle detection. These devices were first deposited on glass substrates and later on CMOS readout chips. With an optimization of the material properties and of the diode, a dark current of 1 pA/cm2 could be achieved on p-i-n structures at reverse bias voltage of 1 V. CMOS imagers, incorporating these optimized diodes were then fabricated and characterized. Very thick diodes (with thicknesses up to 50 μm) were also optimized and deposited on glass and on CMOS readout chips. Particle detectors in TFA technology with 12 and 30 μm a-Si:H n-i-p diodes have been fabricated and characterized using light pulse illumination. Direct detection of single low-energy beta particles has been demonstrated.
An Amorphous Silicon Photoconductor for UV Detection
Authors: Hillebrand Matthias , Blecher Frank , Sterzel Jürgen , Böhm Markus 
Published: June 2019

AbstractAn amorphous silicon photoconductor to detect wavelengths between 180 nm to 550 nm without scintillator is presented. The photoconductor is based on a coplanar configuration of the electrodes, similar to measurement structures to determine material characteristics of amorphous layers, e.g. for the Constant Photocurrent Method (CPM). After passing through a thin transparent passivation layer, the incident radiation is directly absorbed in the intrinsic a-Si:H material. The carrier collecting electrical field is applied perpendicular to the incoming light. Test structures have been fabricated with 80 nm thick sputtered chromium contacts on top of a 60 nm carbonized hydrogenated i-layer and a SixNx passivation layer with a thickness of about 36 nm. The spacing between the Schottky contacts is varied between 3 μm and 100 μm. They are deposited on top or below the a-SiC:H layer. First experiments with this simple coplanar design show that with an increasing voltage a shift towards UV wavelengths can be observed. The new UV detector is applicable in the field of TFA image sensors (Thin Film on ASIC) and in the new Lab-on-a-Chip concept presently under development at the institute for microsystem technologies.
Post-transit Analysis of Transient Photocurrents from High-Deposition-Rate a-Si:H Samples
Authors: Brinza Monica , Kessel W.M.M. , Smets Arno H.M , Sanden M.C.M van de , Adriaenssens Guy J. 
Published: June 2019

AbstractAn interpretation of post-transit photocurrents in a time-of-flight experiment in terms of the underlying density of localized gap states in the sample is presented for the case of hydrogenated amorphous silicon cells prepared by the expanding thermal plasma technique. It is pointed out that part of the observed current is not generated by re-emission of trapped photo-generated charge and should, therefore, not be used for density-of-states calculations.
Thin Film Cavity Ringdown Spectroscopy and Second Harmonic Generation on Thin a-Si:H Films
Authors: Aarts I.M.P. , Hoex B. , Gielis J.J.H. , Leewis C.M. , Smets A.H.M. , Engeln R. , Nesládek M. , Kessels W.M.M. , Sanden M.C.M. van de 
Published: June 2019

AbstractA set of 8 rf deposited a-Si:H thin films of various thickness (4-1031nm) have been used to explore the applicability of two optical techniques, thin film cavity ringdown spectroscopy (tfCRDS) and second harmonic generation (SHG), for the measurement of small defect-related absorptions. In this paper we will give a first overview of the different aspects of these techniques, which are novel in the field of amorphous silicon materials. It is shown that tf-CRDS is capable of measuring defect-related absorptions (associated with dangling bonds) as small as 10-7 for a single measurement, without the need for elaborate calibration procedures. The results are compared with photothermal deflection spectroscopy (PDS) for a broad spectral range (0.7 – 1.7 eV) and show good agreement. Furthermore the existence of a defect-rich surface layer with a defect density of 1.1×1012 cm-2 has been proven. The absorption spectrum of a 4 nm thin film has revealed a different spectral signature than a bulk dominated (1031 nm) film. The SHG experiments on a-Si:H films have shown that the second harmonic signal arises from the surface states and polarization dependent studies have revealed that the surface states probed have an ∞m-symmetry. From this it can be deduced that the absorbing surface states are isotropically distributed. A spectral scan suggests that the second harmonic signal, whose origin has not been unrevealed yet, has a resonance at an incident photon energy of 1.22 eV.
Time-Resolved Switching Studies in a-Si:H and Related Films
Authors: Stradins P. , Jackson W. B. , Branz H. M. , Hu J. , Perkins C.L. , Wang Qi 
Published: June 2019

AbstractSwitching in a-Si:H and a-Si:HNx layers is investigated by pulse current transient and Auger scanning microspectroscopy measurements. Switching in a-Si:H with Ag and Cr contacts exhibits 2 different regimes depending on the voltage pulse polarity. With a positive top Ag contact, switching occurs in nanoseconds after a certain latency time, which depends on voltage exponentially. For a negative Ag contact, there is no latency time provided the voltage exceeds a certain critical value. This might be related to interface effects on contact properties or field-assisted metal diffusion. Scanning Auger element micromaps reveal metallic filaments in the switched films. They contain both Ag and Cr throughout the film thickness. Two phases of the filament formation are suggested – a precursor phase and a post-switching phase characterized by local heating and atomic diffusion. Soft and hard switching are observed in a-Si:HNx films simultaneously and their rates depend strongly on the contact material and applied voltage. Soft switching might be related to the charge trapping in this wide bandgap material.
Threshold Voltage Performance of a-Si:H TFTs for Analog Applications
Authors: Karim K.S. , Sakariya K. , Nathan A. 
Published: June 2019

AbstractAmorphous silicon (a-Si:H) thin-film transistors (TFT) used in emerging, non-switch applications such as analog amplifiers or active loads, often have a bias at the drain terminal in addition to the gate that can alter their threshold voltage (VT) stability performance. At small gate voltages (0 ≤ VST ≤ 15 V) where the defect state creation instability mechanism is dominant, the presence of a bias at the TFT drain is found to decrease the shift in VT (ΔVT) compared to the ΔVT in the absence of a drain bias. In this paper, a ΔVT model accounting for TFT drain bias, is used to predict the performance of a-Si:H analog circuits in active pixel sensor (APS) medical xray imaging and active matrix, organic light emitting diode (AMOLED) display applications.