bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wafer Curvature Studies of Strengthening Mechanisms in Thin Films on Substrates
Authors: Leung O. S. , Nix W. D. 
Published: April 2011

AbstractThe effects of film thickness and passivation on plasticity of thin metal films on substrates have been studied using gold films as a model system. Wafer curvature/thermal cycling measurements were used to study plasticity in films ranging in thickness from 0.2 to 2.5 micrometers. We were able to describe these stress-temperature curves using a simple phenomenological model for linear kinematic hardening. The yield stresses revealed by the modeling were inversely proportional to the film thickness for thicknesses greater than about one micrometer. This relationship is expected from a dislocation model of plasticity. However, the residual stresses in thinner films are substantially lower than this relationship would predict and on unloading, these films show stress-temperature plots not predicted by the model. Stress-temperature curves were also measured after a tungsten passivation was deposited on the gold surface. Films thinner than one micrometer were substantially strengthened by this passivation and could then be described by the linear kinematic model. The observed stresses are only minimally affected for films thicker than about a micrometer. This strengthening effect on thinner films is consistent with the complete blocking of grain boundary diffusion near the free surface of the film.
A Methodology for the Calibration of Spherical Indenters
Authors: Swadener J. G. , Pharr G. M. 
Published: April 2011

AbstractSpherical indentation with continuous load and depth measurement is a useful technique for characterizing thin film mechanical properties. With this technique, the initial loading is in the elastic range. Therefore the elastic-plastic transition can be observed. However, the calibration of spherical indenters presents special problems. First, the radius of the indenter at the point of contact must be determined, and any deviation from a spherical radius must be evaluated. The shape of the indenter also causes mounting difficulties that can create a relatively large and nonlinear compliance in the testing machine. The calibration of spherical indenters is further complicated, because asperities on the indenter and surface roughness add to the uncertainty in locating the surface of the sample. In addition, spherical indenters are generally made of anisotropic single crystals, and the calculation of their elastic responses must include this anisotropy. To address these issues, a methodology has been developed for the calibration of spherical indenters, whereby indentation experiments are conducted on multiple ceramic materials in the elastic range. The method was used to determine the local radius of synthetic sapphire spherical indenters. The accuracy of this measurement was verified using confocal microscopy. The method was successfully applied to an indenter with a nonlinear machine compliance. Further results involving indentation in the plastic regime are also presented.
Strain Relaxation in Thin Films: the Effect of Dislocation Blocking
Authors: Goodhew Peter J 
Published: April 2011

AbstractThe relaxation of strained layers frequently occurs by the glide of threading dislocations. From very early on in the relaxation process, gliding dislocations will be forced to intersect a number of prior dislocations with almost-perpendicular line directions and their progress may be blocked. This effect has been widely reported in semiconductor films, and there is some experimental evidence that it is reduced when layers are grown on vicinal substrates. This implies that the blocking is sensitively dependent on the dislocation configuration and in particular on the dislocation line directions.In this paper the interactions between gliding threading dislocations and the perpendicular or nearly-perpendicular dislocation in their path are modelled quantitatively. The differences arising from different initial dislocation configurations and different predominant line directions are found to be small. Strain relaxation, at least in its early stages, should be virtually independent of the initial dislocation configuration.
Plasma Etching Damage to Ferroelectric SrBi2Ta2O9 (SBT) Thin Films and Capacitors
Authors: Cho Jun Hee , Kwon Il Young , Park Chanro , Choi Chang Ju , Seol Yeo Song , Pyun D. S. , Choi Il Hyun 
Published: April 2011

AbstractThe effects of reactive ion etching damage on the electrical properties of Pt/SBT/Pt capacitors have been investigated. The plasma treated SBT/Pt layers showed a significant decrease in remanent polarization compared with that of the reference sample. The remanent polarization of the plasma treated layers varied with the gas ratios of the Cl2/Ar plasma. XPS analysis of the plasma treated SBT/Pt samples showed that the surface composition was significantly changed as the gas ratios were varied, which resulted in a polarization decrease in the plasma treated samples. Plasma treatment also caused a voltage shift of the hysteresis loops along the voltage axis. The magnitude of the voltage shift was increased for the chlorine-rich plasma. The results of surface analysis revealed that the voltage shift is caused by oxygen deficiency at the SBT surface. Based on our experimental results, reactive ion etching damage was explained in terms of physical and electrical effects of the plasma on the electrical properties of the ferroelectric Pt/SBT/Pt capacitors.
A Structural Study of SrBi2Ta2O9 - Bi3TiNbO9 Ferroelectric Thin Films
Authors: Ching-Prado E. , Pérez W. , Dobalt P. S. , Katiyart R. S. , Tirumala S. , Desu S. B. 
Published: April 2011

AbstractThin films of ferroelectric (SrBi2Ta2O9)x(Bi3TiNbO9)1-x layered structure (for x = 0.0, 0.2, … 1.0) were prepared by a metal organic solution deposition method on Pt/TiO2/SiO2/Si substrates. Raman spectroscopy, X-ray diffraction, atomic force microscopy (AFM), and electrical characterization techniques were utilized to study the inclusion of SrBi2Ta2O9 (SBT) in the Bi3TiNbO9 (BTN) system. The Raman spectra show frequency shifts and broadening of modes as x increases from 0.0 to 0.4, which are related to the nature of Sr and Bi in the A-sites, and Ta, Ti, and Nb in the B-sites. Smooth surfaces without any cracks or defects were evidenced in each of these films by AFM. These images also indicate that the grain size in the films increases with increasing SBT content in the BTN compound. Electrical measurements show that the remanent polarization (Pr) and the coercive field (Ec) values in the x=0.0 film (2 μC/cm2 and 30 kV/cm, respectively) increase to 12.5 μC/cm2 and 125 kV/cm for x=0.6. A decrease in these parameters was found for higher compositions.
Characteristics and Applications of Sr-Modified Ferroelectric Pb(Zr,Ti)O3 Thin Films
Authors: Lee K. B. , Ju B. K. , Desu Seshu B. 
Published: April 2011

AbstractWe have investigated the structural and electrical properties of Sr-modified Pb(Zr,Ti)O3, i.e., (Pb1-xSrx)(Zr0.53Ti0.47)O3 (PSZT), thin films. Sol-gel derived PSZT films were deposited by spin casting onto Pt/Ti/SiO2/Si substrates. Ferroelectric perovskite phases were found for all specimens (x ≤ 0.6), which implied the successful substitution of Sr for Pb. The values of dielectric constant (εr) as well as remanent polarization (Pr) of PSZT capacitors decreases monotonically with increasing Sr for x ≥ 0.1. PSZT (x=0.4) thin film was found to be applicable to high permittivity films for high density dynamic random access memories, whose Pr and εr are 5 μC/cm2 and 350, respectively, and leakage current density is low as 1×10−7 A/cm2 at a electric field of 100 kV/cm. In this paper, we also discuss the characteristics of Sr-modified PbTiO3 thin films.
High-Endurance Scalable PZT Capacitors Using Thin SRO/Pt Stacked Electrodes
Authors: Yamakawa K , Arisumi O. , Hidaka O. , Morimoto T. , Kunishima I. , Tanaka S. , Arikado T. 
Published: April 2011

Abstract90nm-thick PZT capacitors using Pt/thinSRO stacked electrodes showed 2V operation capability, no remanence degradation after more than 1E10 switching cycles, and low imprint. Effects of SRO(SrRuO3) electrode have been studied for high-endurance PZT capacitors. In capacitors with only top SRO electrodes, the SRO increased polarization and improved saturation property compared to Pt electrode PZTs. Fatigue and imprint degradation was caused by Pt bottom electrode interface deterioration. It is thought that the oxygen vacancies created with Pb vacancies are important respecting endurance and retention. PZT films crystallized on SRO showed smaller coercive voltage Vc (2/3 of that for PZT/Pt) with random orientation. The SRO layers block Pb diffusion and supply oxygen, thereby resulting in less oxygen vacancy accumulation at PZT interfaces. We have improved the imprint property by the reduction of thermal budget in SRO/PZT/SRO structures.
Low Temperature Hydrogen Induced Degradation of (Ba,Sr)TiO3 Thin Film Capacitors
Authors: Baniecki J. D. , Parks C. , Laibowitz R. B. , Shaw T. M. , Lian J. , Costrini G. 
Published: April 2011

AbstractWe have used electrical characterization and secondary ion mass spectroscopy (SIMS) to investigate the influence of hydrogen or deuterium (H/D) on the degradation of the electrical properties of metal/Ba0.7Sr0.3TiO3/metal (M/BSTO/M) thin film capacitors after forming gas annealing (FGA). Leakage and dielectric relaxation currents increase after FGA at temperatures as low as 23C. SIMS profiling shows that at 23C H/D diffuses through thin film metal electrodes and accumulates at electrode interfaces. The location (top or bottom electrode interface) of H/D accumulation is dependent on the type of electrodes and capacitor structure. The resulting asymmetric distribution of H/D leads to large voltage offsets in the C-V characteristic, asymmetric leakage currents, and increased dielectric relaxation currents. Possible mechanisms for increased leakage and relaxation currents after FGA are discussed.
Chemical Vapor Deposition and Electrode Technologies for (Ba,Sr)TiO3 Capacitor Used in Gigabit Dram
Authors: Eguchi K. , Hieda K. , Nakahira J. , Kiyotoshi M. , Nakabayashi M. , Yamazaki S. , Izuha M. , Aoyama T. , Tsunoda K. , Lin J. , Nakamura K. , Niwa S. , Tomita H. , Shimada A. , Kohyama Y. , Ishibashi Y. , Fukuzumi Y. , Arikado T. , Okumura K. 
Published: April 2011

AbstractWe review our capacitor technology using (Ba,Sr)TiO3 (BST) as a capacitor dielectric for dynamic random access memory (DRAM) application. Among a number of issues for BST capacitor process integration in DRAM cells, two important technologies are discussed. As an electrode technology, we propose All PErovskite Capacitor (APEC) technology, in which conducting perovskite oxide of SrRuO3 (SRO) is used as capacitor electrodes. For chemical vapor deposition (CVD) of BST, we propose In-situ Multi-Step (IMS) process, which is a sequential repetition of low temperature deposition of ultra thin BST film and crystallization in the same chamber. By using APEC technology and IMS CVD process of BST, we can simultaneously achieve good electrical characteristics (low leakage current and high permittivity) and good step coverage. The combination of APEC technology and IMS CVD process of BST is a promising BST capacitor process technology for future DRAMs.
Interface Properties Between SrTiO3 Thin Films and Electrodes
Authors: Clark A. M. , Hao Jianhua , Si Weidong , Xi X. X. 
Published: April 2011

AbstractSrTiO3 (STO) thin films were grown by pulsed laser deposition on single crystal STO substrates with a SrRuO3 buffer layer, which also serves as a bottom electrode. Measurements of the low frequency dielectric properties were performed in a parallel plate capacitor configuration for a range of temperatures using different top electrode materials. The contribution to the interfacial potential from Schottky barriers was investigated. In comparison to STO single crystals, thin films have continued dielectric non-linearity above T ∼ 70 K. This complicates conventional Schottky barrier height measurements using C-V curves because both Schottky barriers and dielectric non-linearity result in a decrease in dielectric constant under applied electric fields. However, by using I-V data, difficulties related to field dependence of the dielectric constant may be removed. Barrier height measurements for both metal and oxide electrodes were performed for T > 70 K. Calculated barrier heights from a modified Schottky equation were very low for an oxide electrode, and an order of magnitude higher for a normal metal electrode.
Domain Imaging, Polarization Hysteresis, and Switching in Nano-Size Ferroelectric Structures
Authors: Harnagea C. , Pignolet A. , Alexe M. , Hesse D. , Gösele U. 
Published: April 2011

AbstractA fundamental issue in the physics of ferroelectric memories and piezoelectric devices is to study how their properties scale with the size of the ferroelectric structure. In this work we present results concerning the ferroelectric behavior of structures with lateral sizes in the range 100 nm to 1 μm. The ferroelectric characterization was achieved using the piezoresponse mode of a scanning force microscope. 100 nm patterned PZT polycrystalline structures as well as 200 nm epitaxial SrBi2Ta2O9 grains exhibit distinct ferroelectric hysteresis loops. Fatigue measurements on 500 nm structures of PZT were also performed and are discussed.
Investigation of the Structural and Microstructural Characteristics of Sol-Gel Derived Lead Lanthanum Titanate Thin Films
Authors: Majumder S. B. , Bhaskar S. , Dobal P. S. , Cruz A. L. Morales. , Katiyar R. S. 
Published: April 2011

AbstractIn the present work we have studied the characteristics of Pb1.05-xLaxTil-x/4O3 ( x= 0 to 30 at%) thin films prepared by acetic acid and methoxy-ethanol based sol-gel techniques. We have found that higher intermediate temperature fired films (x=0.15), prepared by acetic acid modified technique yielded (100) textured growth with improved dielectric properties. It has been argued that homogeneous mixing of the film constituents in the sol is influenced by the choice of the precursor materials and preparation methodology which in turn controls the growth characteristics and electrical properties. Lanthanum as a dopant has a pronounced influence on the structure, microstructure and electrical properties of the deposited films. In the Raman spectra, the soft E(1TO) phonon shifts towards the lower frequency with a sharp decrease in its intensity and a tetragonal to cubic structural transformation (for 26.5 at % La) was observed at room temperature. In the ferroelectric composition range (up to 15 at % La doping), we have observed a significant improvement of ferroelectric properties with the La addition.
Evaluation of Ferroelectricity in MFIS Type Capacitor Using Pulsed C-V Measurements
Authors: Fujimura Norifumi , Yoshimura Takeshi , Ito Taichiro 
Published: April 2011

AbstractWe have been proposing YMnO3 with low remanent polarization and dielectric permittivity as a transistor type FeRAM. Conventional C-V measurements are normally used to evaluate the ferroelectricity of ferroelectric thin films on Si substrates. For ferroelectric thin films with low polarization, however, there are some issues to understand the C-V hysteresis. For example, interfacial polarization and space charge affect the C-V hysteresis. The effect of interfacial polarization on C-V behavior was calculated assuming the connection of ferroelectric and dielectric layers with different resistivity. If a ferroelectric layer with a leakage current of 1×10-6 A/cm2 is connected to the dielectric layer with a leakage current of 1×10-9 A/cm2, a charge density of 10-9 C/cm2 should be generated in the period of 0.2 sec. Space charge should have a longer time constant for accumulating the charge. Pulsed C-V measurement must be effective to avoid these issues. This paper proposes a simple method to evaluate the real component of ferroelectricity in the C-V hysteresis using YMnO3 or ZnO:Li with very low remanent polarization.
Deposition of Pb(Zr,Ti)O3-Thin Films on Substrates with Shape Memory Effect
Authors: Biegel W. , Klarmann R. , Kuhn M. , Wörz B. , Stritzker B. 
Published: April 2011

AbstractPulsed Laser Deposition (PLD) was used to deposit La-doped Pb(Zr,Ti)O3 (PZT) thin films onto NiTi foils. The substrate alloy with composition Ni50Ti50 shows a strong shape memory effect with a transition temperature of about 80°C. This simple bicomponental system could have the potential of an actuator device (NiTi shows a strain up to 5 % during thermal cycling) with an inherent sensorial component (PZT) for the generated elongation. The deposited ceramic films were characterized with respect to their structural properties (XRD) and their ferroelectric behavior (P-E hysteresis). Under certain deposition conditions the growth of pure perovskite PZT on the polycrystalline shape memory alloy was observed. The growth morphology of PZT on NiTi was compared to the one of PZT on single crystalline substrates whereas no distinctive texture of the films on NiTi could be found. The ferroelectric behavior of the PZT films depend on the stage of bending of the film-substrate compound.
Low Temperature Crystallization of PbTiO3 Thin Film by Excimer Laser Irradiation
Authors: Mihara T. , Mochizuki S , Ishida T. , Sato Y , Nishii J. 
Published: April 2011

AbstractLowering the fabrication temperature for ferroelectric films is very important not only for silicon monolithic circuits but also for various substrates. Amorphous PbTiO3 thin films were prepared on glass substrates using ArF pulsed laser deposition (PLD). They were subsequently treated by a laser-induced phase transformation technique to achieve a perovskite structure. After irradiation by an ArF pulsed laser with an energy density 50mJ/cm2 in air, the films crystallized into the perovskite structure. It was possible to maintain the substrate at room temperature during the whole fabrication process. The structure, morphology and composition of the films were characterized by X-ray diffraction diffractometry (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), respectively. The surface of film irradiated with a laser was often rather rough and peeled off everywhere. It was necessary to control the number of laser pulses to avoid damaging the films. The effects of chemical composition and fabrication temperature are also discussed.
Heteroepitaxial Growth of Ir/ZrN Layered Electrode on (100)Si Substrate for Ferroelectric Capacitor
Authors: Horii Sadayoshi , Yokoyama Seiji , Horita Susumu 
Published: April 2011

AbstractAn Ir film was grown heteroepitaxially on the epitaxial (100)ZrN film deposited on the (100)Si substrate by sputtering. Further, we obtained a heteroepitaxial (001)PZT film on the epitaxial (100)Ir/(100)ZrN/(100)Si substrate structure by reactive sputtering. The crystallographic relationship was cube-on-cube. The polarization-electric field hysteresis loop of the 300-nm-thick epitaxial PZT film with a top electrode of IrO2 showed a saturated square shape at an ac amplitude of 5V, and the remanent polarization, 2Pr, and coercive field, 2Ec, were 60 μC/cm 2 and 80 kV/cm, respectively. The Pr was not reduced up to 5×1010 switching cycles with a ±10 V bipolar pulse train. The leakage current of the PZT film at +5 V and –5 V was about 8.0× 10−8 and 2.5 ×10−7 A/cm2, respectively.
Laser-Based Flat Panel Displays
Authors: Bischel W. K. 
Published: April 2011

AbstractGemfire is developing a novel wall-mounted display technology called Polymer Switch Matrix (PSM). Featuring significant advantages in performance, manufacturability and scalability, it represents a fundamental change in the way flat panel displays are designed and manufactured. The perceived market opportunity, operating principle, system architecture and feasibility demonstration of this radically new laser based technology are described.
Optical and Electro-Optic Properties Of Highly Oriented (Sr,Ba)Nb2O6 Thin Films Prepared by Sol-Gel Process
Authors: Koo Junmo , Jang Jae Hyeok , Bae Byeong-Soo 
Published: April 2011

AbstractHighly c-axis oriented SBN thin films with various compositions were obtained on MgO(100) and Pt(100)/MgO(100) substrates. The anisotropy of refractive indices (no and nc) of c-axis preferred oriented films on MgO(100) substrates decreases certainly as Sr content in the film composition increases. The optical propagation loss of the films decreases with increasing Sr content due to the reduction of the optical scattering by the anisotropy of refractive indices. The oriented films show the linear electro-optic effect with large electro-optic coefficients. The coefficient of the films increases as the Sr content increases because the linear electro-optic coefficient is dependent on the spontaneous polarization and the dielectric constant of the films.
Nonlinear Fiber Core Liquid and Nematic Liquid Crystal Film for Wide Temporal Bandwidth Optical Limiting Application
Authors: Khoo I. C. 
Published: April 2011

AbstractNonlinear absorption processes in an extremely nonlinear optical fiber core liquid, and recently observed supra-optical-nonlinearity in dopant modified nematic liquid crystals, are discussed in the context of optical limiting and anti-laser dazzling application.
Maximum Cross Sections for Excited State and Two-Photon Absorption
Authors: Becker Roger J. 
Published: April 2011

AbstractThere is a maximum value for any nonlinear process, which can be found on the basis of fundamental quantum mechanics. With regard to single photon processes, there is a maximum absorption cross section, σa, which any molecule may reach. The maximum is 1.13 × 10-17 λ is the wavelength of the light, n is the refractive index of the host medium, and Q is the quality factor ascribed to the absorption line width. Thus large cross sections can only be obtained at the expense of a narrow operating range. The maximum is set by fundamental physics. Since nonlinear phenomena are highly resonant, the maxima of higher-order processes are also a strong function of the width of the resonance and the peak wavelength. In the case of twophoton absorption the peak value of the maximum cross section, σ2N or δ, is roughly 3.5 × 10-32 λ4nQ cm4/GW, or about 7 × 10-57 λ3 nQ cm4/photon. No value for a nonlinear coefficient is meaningful in the absence of the width of the resonance, the wavelength, and the refractive index of the medium at the wavelength of the measurement.The basic quantity of interest is the linear electronic polarizability. This fundamental quantity determines not only the absorption for the various processes of interest, but also the surface tension and the closely related solubility parameter. All scale with the polarizability a. The polarizability has a maximum value of e2/mω2; consequently the absorption cross sections have a corresponding ceiling. The maximum value for the peak in a resonant polarizability curve is set by a balance between the Coulomb potential energy of the electron and its kinetic energy. Hence it is an inherent property of the electron itself, irrespective of the molecular orbital in which it finds itself. All that the particular quantum configuration of the molecule does is partition the line strength for absorption among various possible transitions. The extreme case is when virtually all the strength is concentrated in a single transition, an inherently resonant condition.