bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Investigation of Au-Ag Interface Formed by Cold Welding Using Focused Ion Beam/Transmission Electron Microscopy
Authors: Cao Yifang , Yao Nan , McIlwrath Kevin , Zhou Jikou , Osinkolu Gabriel , Soboyejo Winston O. 
Published: April 2011

ABSTRACTThis paper reports the recent results of a transmission electron microscopy study of cold-welded and e-beam deposited Au-Ag interfaces. Dust particles were observed to be embedded between the cold-welded interfaces. These are shown to amplify the defect regions caused by surface asperities. Electron energy loss spectroscopy (EELS) analysis revealed that there was no significant diffusion zone across the cold welding interface. However, sub-micron mechanical twining structures were revealed by transmission electron microscopy (TEM) analyses. These were found to penetrate through both the cold-welded and control Au-Ag interfaces, but with different orientations.
Texture Evolution in Cu Films and Lines
Authors: Chung Chia-Jeng , Field David , Park No-Jin , Woo Christy 
Published: April 2011

ABSTRACTGrain growth in polycrystalline films is controlled by the energetics of the surface, interface and grain boundaries as well as strain energy. The unique character of damascene lines fabricated from electroplated Cu films introduces the additional considerations of bath chemistry and geometric constraints. The moderate stacking fault energy of Cu allows for the development of a substantial twin fraction for certain growth conditions. This paper discusses in-situ observation of grain growth in Cu films and lines under various processing conditions. It is shown that for thicker films and for structures constrained within damascene trenches the energetics of twin boundary formation play a large role in texture development of these structures.
Activation of Low k Dielectrc Surfaces for ALD Barrier Formation
Authors: Liu Junjun , Bao Junjing , Shi Hualiang , Ho Paul S. 
Published: April 2011

ABSTRACTAtomic layer deposition (ALD) of ultra-thin barrier layers is a key process for implementation of Cu/low k interconnects. Low k dielectric surfaces are generally characterized by weak surface bonds which have to be properly activated for barrier formation. In this study, we investigated the surface activation of low k dielectrics by atomic hydrogen, nitrogen and ammonia beams for ALD of Ta/TaN barrier layers. In-situ x-ray photoemiision spectroscopy (XPS) together with differential FTIR were used to examine the beam modification of the surface and the subsequent growth on the low k surface. The evolution of the low k surface chemistry revealed an initial transient growth region controlled mainly by the substrate surface chemistry. The initial chemisorption was found to be through formation of Ta-O bonds on organosilicates (OSG) and charge transfer complexes on aromatic SiLK. This led to a significant slower initial nucleation on the OSG low k surface without beam activation. The atomic beams, particularly the nitrogen and amine radials, were found to serve as effective reducing agents in initiating and enhancing the precursor chemisorption. This led to an improvement of the barrier film quality and an increase of the deposition rate at a temperature compatible with low k dielectrics (< 400C). In the subsequent linear growth region, atomic hydrogen species was able to reduce the chlorine content under appropriate temperature and with sufficient purge. The effect of porosity in low k dielectrics on barrier formation will be discussed.
Height Dependent Resistivity of Copper Interconnects in the Size Effect
Authors: Kitada Hideki , Suzuki Takashi , Kimura Takahiro , Nakamura Tomoji 
Published: April 2011

ABSTRACTWe investigated the copper grain size dependence on the interconnect line height using the EBSD (Electron Back Scattering Diffraction) pattern method. In our grain size measurements, we excluded the twin boundaries because of its small contribution to the electron scattering. Our experiments showed that the average grain size of a 70 nm-high line was about 24% smaller than for a 190 nm-high line.We estimated the grain boundary scattering components by the Fuchs-Sondheimer (FS) and the Mayadas-Shatzkes (MS) models including the line height dependence of the grain size parameter (d). In order to evaluate precisely the influence of height dependence of grain size in the FS and MS models, we also determined the surface scattering coefficient of the Ta/Cu and SiC/Cu interfaces by an independent experiment.From this, we found that grain boundary scattering components became approximately 32% larger for the 70 nm-wide line when the line height dependence of the grain size was taken into consideration.
Localized Charge Trapping Memory Cells in a 63 nm Generation with Nanoscale Epitaxial Cobalt Salicide Buried Bitlines
Authors: Mueller Torsten , Kleint C. , Fitz C. , Isler M. , Riedel S. , Sachse J.-U. , Olligs D. , Boubekeur H. , Heinrichsdorf F. , Polei V. , Pritchard D. , Verhoeven M. , Lattard L. , Markert M. , Schupke C. , Tippelt B. , Teichert S. , Reisdorf R. , Ludwig C. , Stein v. Kamienski E.G. , Mikolajick T. , Nagel N. 
Published: April 2011

AbstractA 63nm Twin Flash memory cell with a size of 0.0225μm2 per 2 (or 4) bits is presented. To achieve small cell areas, a buried bit line and an aggressive gate length of 100 nm are the key features of this cell together with a minimum thermal budget processing. A novel epitaxial CoSi2 process allows the salicidation of local buried bitlines with only a few tens of nanometer width.
The Optical and Electrical Properties of SiOx(x<2) Thin Films Prepared by Pulsed Laser Deposition Technique
Authors: Park Byoung Youl , Lee Sol , Bae Chang Hyun , Park Seung Min , Park Kyoungwan 
Published: April 2011

AbstractSiOx (x<2) films were deposited in an O2 atmosphere using Si target in a pulsed laser deposition system. Post-annealing process was employed in an O2 atmosphere to form the nanometer-sized Si crystallites embedded in the SiO2 films. The transmission electron microscope analysis shows the existence of crystalline silicon nano-dots with diameters ranging from 2 to 4 nm. Also, the clear separation of Si and SiO2 phases can be seen in the X-ray photoemission spectra. Photoluminescence peak from the annealed films was obtained, which is attributed to the quantum confinement effect of the Si nano-dots. C-V measurements of the metal-oxide-silicon (MOS) structure containing the silicon nano-dots in the oxide layer were performed to investigate the charging/discharging behavior of the silicon nano-dots. The maximum program window of the MOS was measured to be4.1V under ±5V sweep.
The Study on Charge-trapping Mechanism in Nitride Storage Flash Memory Device
Authors: Wu Jia-Lin , Chien Hua-Ching , Chang Chi-Kuang , Liao Chien-Wei , Lee Chih-Yuan , Wang Je-Chuang , Chen Yung-Fang , Kao Chin-Hsing 
Published: April 2011

AbstractIn this work, the charge-trapping distributions of polysilicon-oxide-nitride-oxide-silicon (SONOS) structure are studied. The trapping energy level of SiNx films with different composition ratio deposited by low-pressure chemical vapor deposition (LPCVD) were first characterized by photoluminescence (PL) measurement. Moreover, using F-N/CHE program and charge pumping techniques, the vertical location and the lateral distribution of programmed charges are investigated in the nitride films with different composition ratio. The study offers strong evidence that the density of charge-trapping levels in the Si-rich nitride is higher than the standard nitride. A simple qualitative model and calculation explains that the trapping level distributions in the SiNx films are shallower by increasing relative Si-content. Furthermore, we have observed the nitride trap vertical location was changed by adjusted Si/N composition ratio. And the lateral distribution of hot electron programmed charges in the modified nitride is broader than that in the standard nitride because it offered more charge-trapping sites and shallower charge-trapping levels. In summary, the study can help researchers to understand the nitride charge-trapping mechanism and the analysis of optical/electrical characteristics.
Resistance Non-volatile Memory – RRAM
Authors: Ignatiev Alex , Wu Naijuan , Chen Xin , Nian Yibo , Papagianni Christina , Liu Shangqing , Strozier John 
Published: April 2011

AbstractElectric-pulse induced resistance (EPIR) change effect encompasses the reversible change of resistance of a thin oxide film under the application of short, low voltage pulses. The phenomenon is widely observed in complex and binary oxides, and is the basis for development of non-volatile resistance random access memory (RRAM). A variety of analytical techniques have been employed to understand the origin of the resistance change with recent data yielding a model incorporating oxygen ion/vacancy diffusion and pile-up near the interface region of the oxide at the impervious metal interface. Further efforts are still required to fine tune the model and apply it to the optimization of RRAM device development.
A Proposal of a Parallel Resistance Model for the Conduction Mechanism of Binary Transition Metal Oxide ReRAM
Authors: Kinoshita Kentaro , Noshiro Hideyuki , Yoshida Chikako , Sato Yoshihiro , Aoki Masaki , Sugiyama Yoshihiro 
Published: April 2011

AbstractA parallel resistance model (PRM), in which the total resistance, Rtotal, is given by a parallel connection of resistance of a filament, Rfila, and that of a film excluding a filament, Rexcl, was proposed to understand DC electric properties of resistive RAM (ReRAM). Here, the relationship of 1/Rtotal = 1/Rfila + 1/Rexcl is satisfied. To prove the validity of this model, the dependence of the relationship between resistance and temperature, R(T), of Pt/NiO/Pt on an area of a top electrode, S, was investigated. It was clarified that R(T) depended on S, which is the result definitely expected by the PRM. It was also clarified that smaller S is crucial to observe intrinsic properties of a filament of ReRAM.
Spectroscopic Ellipsometry Studies of Tb-doped SiO2 Thin Films
Authors: Feng Zhe Chuan , Feng Zhe Chuan , Chang Yia Chung , Li Ting Kai 
Published: April 2011

AbstractThe optical properties of Tb-doped SiO2 films have been studied from multi-wavelength spectroscopic ellipsometry (SE) measurements performed over the 250–1100 nm wavelength range. The SE modeling carried out with care to adhere as much to the ellipsometric fitting qualities. The refractive index dispersions, the layer thickness, and the lateral thickness variation of the films are given and discussed regarding the optical constitution of these films and the ellipsometric validity of these parameters
Preparation of Cu(In1-xGax)Se2 Thin Films and Solar Cells Using a Se-radical Beam Source
Authors: Ishizuka Shogo , Yamada Akimasa , Shibata Hajime , Sakurai Keiichiro , Fons Paul , Matsubara Koji , Niki Shigeru 
Published: April 2011

AbstractWe have grown device-grade Cu(In,Ga)Se2 (CIGS) thin films using a RF-cracked Se-radical beam source. A unique combination of film properties: smooth surface, large grain size and high photovoltaic performance are shown. A competitive energy conversion efficiency of 17 % has been demonstrated from a solar cell fabricated using a CIGS absorber grown with a Se-radical source. In addition to the unique combination of film properties and high photovoltaic performance, a significant improvement in the use of Se source material in comparison with the conventional Se-evaporative sources has been demonstrated.
Zn-Based Buffer Layer and High-Quality CIGS Films Grown by a Novel Method
Authors: Yamada Akira , Meng Fanying , Chiba Yoshiyuki , Kawamura Masahiro , Konagai Makoto 
Published: April 2011

AbstractZnMgO was fabricated by MOCVD and the films were applied to a buffer layer of Cu(InGa)Se2 solar cells.A nove growth method for Cu(InGa)Se2 was described in which cracked Se was utilized.
Preferred Orientation, Grain Sizes and Grain Boundaries of Chalcopyrite-Type Thin Films
Authors: Abou-Ras Daniel , Nichterwitz Melanie , Kaufmann Christian A. , Schorr Susan , Schock Hans-Werner 
Published: April 2011

AbstractChalcopyrite-type thin films - CuInS2, CuInSe2, CuGaSe2, and Cu(In,Ga)Se2 - in various completed solar cells were studied in cross-section by means of electron-backscatter diffraction (EBSD). Valuable information on grain sizes, local grain orientations, film textures, and grain boundaries were extracted from the EBSD linescans and maps. The grain-size distributions from the chalcopyrite-type thin films can be represented well by lognormal distribution functions. The EBSD measurements on CuGaSe2 thin film reveal a <110> fiber texture, in good agreement with x-ray diffraction texture analysis performed on the same sample. The EBSD maps from all samples studied exhibit considerable twinning in the chalcopyrite-type thin films. Indeed, the most frequent types of grain boundaries in these thin films are (near) Σ3 60°-<221> and 71°-<110> twins. It is shown that rotational 180°-<221> twins (which are symmetrically equivalent to 71°-<110>) are more frequently found than anion- or cation-terminated 60°-<221> twin boundaries.
Real-Time Investigations on the Formation of Cu(In,Ga)Se2 While Annealing Precursors Produced with a Combination of Sputtering and Thermal Evaporation
Authors: Jost Stefan , Hergert Frank , Hock Rainer , Purwins Michael 
Published: April 2011

AbstractWe have investigated the formation of Cu(In,Ga)Se2 thin films by real-time X-ray diffraction (XRD) experiments while annealing differently deposited and composed stacked elemental layer (SEL) precursors.The in-situ measurements during the selenization of bi-layered Cu/In precursors reveal, that the semiconductor formation process is similar for precursors with thermally evaporated or sputtered indium. In both cases, the formation of binary copper and indium selenides is observed at temperatures around the melting point of selenium. After subsequent selenium transfer reactions, the chalcopyrite CuInSe2 is formed from the educt phases Cu2-xSe and InSe.The addition of gallium leads to the formation of the intermetallic precursor phase Cu9Ga4, which reduces the overall amount of copper and gallium selenides at process temperatures above 500 K. This causes an ongoing selenization in the indium selenium subsystem, which results in the formation of CuInSe2 from the educt phases Cu2-xSe and the selenium richest indium selenide g-In2Se3.
Bandgap Engineering in Indium SulfideThin Films by Tin Mixing
Authors: Mathew Meril , Kartha C. Sudha , Vijayakumar K.P. , Elgin John , Hari Parameswar 
Published: April 2011

AbstractIn2S3 thin films appear to be a promising candidate for photovoltaic applications due to its stability, wide band gap and photosensitivity. The optical band gap value of Indium sulfide (In2S3) thin films reported in the literature varies from 2.0 eV to 2.4 eV following their synthesis process. These values are too small for an application as buffer layer in solar cells. In Present work, we report that incorporation of Sn using [SnCl4.5H2O] could increase the bandgap to wider ranges. In2S3/Sn thin films were deposited on soda lime glass substrate using chemical spray pyrolysis (CSP) technique. The spraying solution contained indium chloride (InCl3), thiourea [CS(NH2)2] and [SnCl4.5H2O]. Studies were done on films prepared using different Sn/In ratios. Depth profile using x-ray photoelectron spectroscopy showed that incorporation of Sn increased the concentration of oxygen in the samples. Band gap of the films increased with increase in Sn/In ratios. Depending on the ratios, bandgap could be varied from 2.72 eV to 3.78 eV. At lower mixing levels wide band gap low resistive In2S3/Sn films could be obtained which is highly useful for buffer layer applications. Low resistive buffer layer will decrease the series resistance of the cell and wider band gap will improve light transmission in the blue wavelength, both these factors help in increasing the short circuit current of the photovoltaic cell. Samples having higher Sn/In ratios showed wider band gap (up to3.78 eV).Though the samples had very high bandgap and high resistivity these samples were highly photosensitive [(IL-ID)/ID = 11,000]. The results proved that tin incorporation modified the band gap and electrical properties of the In2S3/Sn films favorably over wider ranges making it highly suitable for different optoelectronic applications.
Electron Spin Resonance and Ultra Violet (UV) Photoluminescence of Ge Implanted CuGaSe2 Thin Films Prepared by the CCSVT (Chemical Close-spaced Vapor Transport) Technique
Authors: Doka Serge , Hofstetter Jasmin , Rusu Marin , Arushanov Ernest , Klaus Lips , Schedel-Niedrig Thomas , Lux- Steiner Martha Ch. 
Published: April 2011

AbstractNon-equilibrium ion implantation of Ge in p-type polycrystalline thin film CuGaSe2 (CGSe) prepared by Chemical Close-spaced Vapor Transport (CCSVT) has been performed with the goal to achieve n-type doping of this chalcopyrite semiconductor. Using Electron Spin Resonance (ESR) it is shown that Ge implantation induces a paramagnetic specie at g = 2.003. A model is proposed that assigns the ESR signal to electrons trapped by donor states that are electrically inactive. Moreover, UV photoluminescence of Ge implanted films has evidenced a new peak emission at 1.47 eV, which is resolved as a radiative recombination of a hole bound to the native copper vacancy and an electron bound to a deep donor with an ionization energy of ED =360±10 meV.
Influence of Deposition Parameters on the Morphology of CdTe Films and on the Performance of CdTe Solar Cells
Authors: Hädrich Mathias , Mack Sebastian , Metzner Heinrich , Reislöhner Udo , Witthuhn Wolfgang 
Published: April 2011

AbstractFor industrial CdTe solar cell production, thin, dense and pinhole-free films have to be deposited at high rates. Using a close-to-industrial close space sublimation (CSS) process, we deposited CdTe films at different temperatures and rates. The morphology of these films was analyzed by scanning electron microscopy (SEM) and x-ray diffraction (XRD). The measurements show the size, size distribution and orientation of the grains to strongly depend on deposition temperature and rate. A suitable combination of these parameters yields large grains of about 3 microns diameter even for deposition temperatures below 750 K and at high deposition rates of 3 microns per minute. The interplay of CdTe layer morphology and solar cell performance is elucidated employing a TCO-CdS-CdTe-Mo film sequence for complete solar cells.
Modelling of Nanoindentation of Compliant Layers on Stiffer Substrates using Finite Element Analysis
Authors: Clifford Charles A , Seah Martin P 
Published: April 2011

AbstractNanoindentation using an Atomic Force Microscope (AFM) or a nanoindenter was modelled using Finite Element Analysis (FEA). Force versus indentation depth data were taken for a system consisting of a compliant layer on a stiffer substrate. It was found that the FEA results may be expressed analytically by a simple function that describes the reduced modulus value obtained with Oliver and Pharr's method for any moduli values, thickness of layer or radius of the indenter tip. Initial results obtained by varying the Poisson's ratio of the layer and substrate are also presented.
Contribution of Solvothermal Processes to the Synthesis of Novel Nitrides and the Development of Shaping Processes
Authors: Demazeau Gerard , GOGLIO Graziella , LARGETEAU Alain 
Published: April 2011

AbstractSolvothermal processes can be described as the reaction or the decomposition of precursor(s) in presence of a solvent in a close system at a temperature higher than the solvent boiling point. Consequently pressure parameter is involved. Such processes are mainly managed by two sets of parameters: (i) thermodynamical parameters and (ii) chemical parameters.Solvothermal processes concern either supercritical or subcritical conditions, -homogeneous or heterogeneous systems, and thermodynamical parameters (P and T) play an important role. The main interest of solvothermal reactions is the improvement of the chemical reactivity, and in such a case the nature of the reagents and the physico-chemical properties of the solvent are important.For the last 20 years, solvothermal processes have been developed in different research areas, such as:- synthesis of new compounds (including in particular hybride systems),- crystal growth of functional materials,- preparation of nanocrystallites with well defined size and morphology,- deposition of thin films,- sintering in mild temperature conditions.In particular, solvothermal reactions involve nitrides and derived materials either for preparing new compositions or shaping functional nitrides (single crystals, nanoparticles…).In a first approach the synthesis of nitrides using solvothermal reactions will be described versus the nature of the precursors and the composition of the solvent. The nitriding process will be analyzed versus the chemical species, in particular N3−, N3−…Different illustrations will be described (transition metal nitrides, light elements-based nitrides…).The second part will be devoted to the development of solvothermal processes for the preparation of single crystals or nanocrystallites.As a conclusion, the potential developments of solvothermal nitriding processes either in basic research or industrial applications will be discussed.
Molecular Beam Epitaxy of Nonpolar Cubic AlxGa1−xN/GaN Epilayers
Authors: As Donat , Potthast Stefan , Schoermann Joerg , Tschumak Elena , de Godoy Marcio F. , Lischka Klaus 
Published: April 2011

AbstractCubic AlxGa1-xN films were grown by molecular beam epitaxy on freestanding 3C-SiC (001) substrates with an Al mole fraction of x=0 to 0.74. Using the intensity of a reflected high energy electron beam as a probe we find optimum growth conditions of c-AlGaN when a one-monolayer gallium coverage is formed at the growing surface. Clear reflection high energy electron diffraction oscillations during the initial growth of AlxGa1-xN/GaN layers were observed. The growth rate was about 177 nm/h. We find that the aluminium mole fraction is only determined by the aluminium flux, and that the AlxGa1-xN growth rate is independent on the aluminium content. Atomic force microscopy exhibits smooth surfaces with a RMS roughness of about 5 nm on 5×5 µm2 areas. Cathodoluminescence spectroscopy revealed clear band edge emission up to an aluminium mole fraction of x=0.52, showing a linear relation between the band gap energy and the Al composition.
Shock Wave Synthesis and Exploration of High-pressure Nitrides and Related Materials
Authors: Sekine Toshimori 
Published: April 2011

AbstractWe have successfully developed a method to manufacture spinel-type Si3N4 and also a chemical treatment method to separate the spinel-type phase from the low-pressure phases. Similar methods could be applied for the SiAlON systems. In order to explore high-pressure nitrides and oxynitrides, we extended toward the system Si3N4-AlN-Al2O3- SiO2. According to the results of in situ measurements of the high-pressure behavior up to pressures of 200 GPa, there appears to be post-spinel phase in the system. This is consistent with the results from the first principles calculations. However we could not obtain the post-spinel phase by the shock recovery experiments at present. We also carried out shock recovery experiments on carbon nitrides and related materials. Experimental results showed formation of a new carbon nitride, high stability of melamine up to a shock pressure of 37 GPa, and production of amorphous C-N materials with a highest N/C ration of 1.26 from the reaction between carbon tetrahalide and sodium dicyanoamide. We tried further to extend toward the systems C3N4-Si3N4 and Mg2SiO4-Si3N4, after taking into account the results on shock synthesis of spinel-type nitrides.