bluuebunny/crossref_metadata_2025_split huggingface dataset:
Novel Chain Stack Capacitor for 32Mb FeRAM and Beyond
Authors: Bruchhaus R. , Ozaki T. , Ellerkmann U. , Lian J. , Kumura Y. , Kanaya H. , Yabuki M. , Tsuchya T. , Hilliger A. , Egger U. , Tomioka K. , Moon B. K. , Itokawa H. , Zhuang H. , Natori K. , Beitel G. , Sugimoto S. , Yamakawa K. , Kunishima I. , Nagel N. 
Published: April 2011

ABSTRACTFor high density FeRAM devices small cell sizes are essential. The combination of the capacitor on plug (COP) structure with the Chain FeRAM™ cell design is used to develop a 32Mb FeRAM. Based on a 0.2 μm standard CMOS process a silicide capped polysilicon plug is used to contact the bottom electrode of the ferroelectric capacitor to the transistor. The barrier contact to the plug is formed by IrO2/Ir and a sputter deposited PZT (40/60) is used as ferroelectric material. The function of SrRuO3 (SRO) layers at the electrode/PZT interfaces is described in more detail. Double sided SRO results in slightly lower coercive voltage and imprint behavior compared to capacitors without SRO. Double sided SRO is essential to achieve excellent fatigue behavior measured up to 1×1011 switching cycles.
Fabrication and Properties of Thin Pb(Zr,Ti)O3 Film Pockels Cell
Authors: Vieitez M. O. , Khartsev S. I. , Grishin A. M. 
Published: April 2011

ABSTRACTLongitudinal Pockels cell as a vertical ferroelectric Pb(Zr0.53Ti0.47)O3 (PZT) thin film capacitor was fabricated by pulsed laser deposition technique onto the both side polished YAlO3 + 1% Nd2O3 single crystal substrate. At first, conducting La0.5Sr0.5CoO3 (LSCO) 100 nm thick layer was deposited as an atomic template for 1 m thick PZT film. Epitaxial quality (exceptional c-axis orientation and coherent in-plane texture) of PZT/LSCO/Nd:YAlO3 (001) heterostructure has been confirmed by x-ray diffraction. On the top, semitransparent 100 nm thick Au electrode was deposited by thermal evaporation. Intensity of the chopped 670 nm polarized laser radiation transmitted through the Au/PZT/LSCO/Nd:YAlO3 cell was measured using lock-in amplifier. Special precautions were employed to get reproducible transmittance vs. temperature scans up to 400 °C. Phenomenon of critical opalescence (scattering of the light with critical fluctuations of polarization) was observed in the vicinity of Curie temperature at 208 °C. Modulation of the transmitted light as high as 3% was achieved applying 20 V (200 kV/cm) across the capacitive cell, whereas the voltage tunability measured at 1 kHz from C-V characteristics was about 70%.
Wafer Bonding and Layer Transfer For Thin Film Ferroelectrics
Authors: Ruglovsky Jennifer L. , Park Young-Bae , Ryan Cecily A. , Atwater Harry A. 
Published: April 2011

ABSTRACTWe report on the layer transfer of thin ferroelectric materials onto silicon substrates. H+ and He+ ion implantation created a buried sacrificial layer in the c-cut BaTiO3 and LiNbO3 single crystals. Bubble formation and thermodynamics of cavity at the bonding interface have been investigated, and single crystal thin film layers were transferred onto crystalline silicon substrates. We have found that defects generated by ion implantation in ferroelectric materials can be significantly recovered with the subsequent annealing for layer splitting.
Combinatorial Laser Processing Of Dielectric/Ferroelectric Thin and Thick Films
Authors: Das R. N. , Lew C. , Zergioti I. , Thompson M. O. , Giannelis E. P. 
Published: April 2011

ABSTRACTA library of different crystalline sol-gel thin films with a composition of BaxTiyOz (where x = 1,2; y = 1,2,9 and z = 3, 7, 20) has been generated using variable multi-step laser and thermal annealing. Point by point X-ray diffraction characterization revealed the presence of high dielectric (BaTiO3) and low dielectric (Ba2Ti2O7 and Ba2Ti9O20) phases. Appropriate laser and thermal annealing controlled crystallinity, phase content, morphology and dielectric property of libraries. We have extended the process to BaTiO3 based thick-films and investigated the surface morphology of laser-annealed films.
Ferroelectric and Dielectric Properties of Chemical-Solution-Derived Bismuth Lanthanum Titanate Thin Films with Various Bismuth Oxide Template layers
Authors: Bao Dinghua , Wakiya Naoki , Shinozaki Kazuo , Mizutani Nobuyasu 
Published: April 2011

ABSTRACT(Bi,La)4Ti3O12 (BLT) thin films with various Bi2O3 template layers were prepared on Pt/Ti/SiO2/Si substrates by a chemical solution deposition method. Both of the BLT films with a thin Bi2O3 template layer and those without a Bi2O3 layer had a highly c-axis oriented growth, while both of the BLT films with a thin Bi2O3 bottom layer and those with a Bi2O3 intermediate layer were highly c-axis oriented. It was found that the use of Bi2O3 template layers improved significantly the ferroelectric properties of BLT thin films. In addition, the thin films with a thin Bi2O3 template layer showed good dielectric properties. All the capacitors with Bi2O3 template layers showed high polarization fatigue resistance and good retention properties.
A Novel Ruthenium Precursor for MOCVD without Seed Ruthenium Layer
Authors: Shibutami Tetsuo , Kawano Kazuhisa , Oshima Noriaki , Yokoyama Shintaro , Funakubo Hiroshi 
Published: April 2011

ABSTRACTRuthenium thin films were deposited on SiO2/Si substrates at 275 – 400 °C by metalorganic chemical vapor deposition (MOCVD) using liquid precursor (2.4-dimethylpentadienyl)(ethylcyclopentadienyl)ruthenium [Ru(DMPD)(EtCp) DMPD: 2.4-dimethylpentadienyl EtCp: etylcyclopentadienyl]. Deposition characteristics of the films were compared with those using bis(ethylcyclopentadienyl)ruthenium.The decomposition temperature of Ru(DMPD)(EtCp) was 80 °C lower than Ru(EtCp)2. Both films consisted of Ru single phase for all deposition temperature range and showed an resistivity bellow 20 μΩcm for the films deposited above 300 °C. The initial nucleation of Ru films from Ru(DMPD)(EtCp) precursor was smaller in size and denser than that from Ru(EtCp)2. The deposition process from Ru(DMPD)(EtCp) has much shorter incubation time than that from Ru(EtCp)2.
Characterization of Epitaxial Pb(Zrx,Ti1-x)O3 Thin Films with Composition Near the Morphotropic Phase Boundary
Authors: Saito Keisuke , Kurosawa Toshiyuki , Akai Takao , Yokoyama Shintaro , Morioka Hitoshi , Oikawa Takahiro , Funakubo Hiroshi 
Published: April 2011

ABSTRACT200-nm-thick Pb(Zrx,Ti1-x)O3 (PZT) thin films with zirconium composition in the range from 0% to 65% were epitaxially grown on (001)c SrRuO3 (SRO)//SrTiO3 (STO) single crystal substrates by pulsed metalorganic chemical vapor deposition (pulsed MOCVD). Constituent crystallographic phases were characterized by high-resolution X-ray diffraction reciprocal space mapping. It was found that PZT thin films having zirconium composition from 45% to 60% show mixed tetragonal and pseudocubic phases and their lattice parameters remained constant in this composition range.
New Line of Solid Solution System of Oxide Ferroelectrics
Authors: Kijima Takeshi , Ishiwara Hiroshi 
Published: April 2011

ABSTRACTFerroelectric random access memory is one of the most promising candidates of non-volatile memories and has already been commercialized. However there still exist some problems to be solved on the ferroelectric materials. We succeeded in solving these problems by forming solid solutions between Bi2SiO5 and conventional ferroelectric materials such as Bi4Ti3O12, SrBi2Ta2O9 and Pb(Zr,Ti)O3. It was found that Bi2SiO5 enhanced crystallization of the ferroelectric materials and finally formed solid solutions with them. As a result, the crystallization temperature of the films decreased by 150 to 200 °C, and the ferroelectric and leakage current characteristics did not degrade even in an ultra-thin film of 13 nm in thickness. On the other hand, it was also found that the ferroelectric and insulating characteristics of the BSO-added films were dramatically improved by annealing in high-pressure oxygen up to 9.9 atms.[1] Three-orders-of-magnitude improvement of the leakage current density was observed in BSO-added BLT films after annealing at 9.9 atms, while pronounced increase of the saturation polarization was observed in BSO-added SBT and PZT films. From cross-sectional TEM (Transmission electron microscopy) observation, origin of the improved characteristics was speculated to be the structural change of the films.[2]
Hrteminvestigation of 90° Domain Configureuration and P-E Hysteresis Loop of Epitaxial PZT Multilayered Thin Films
Authors: Kiguchi Takanori , Wakiya Naoki , Shinozaki Kazuo , Mizutani Nobuyasu 
Published: April 2011

ABSTRACTMulti-layered epitaxial Pb(Zrx,Ti1-x)O3 (PZT) films of x=0.2–0.5 were deposited on La0.5Sr0.5CoO3-x (LSCO)/ (001)STO and LSCO/CeO2/YSZ/(001)Si substrates with buffer layers. It was investigated how the 90° domain structure and the P-E hysteresis character depend on the difference of the thermal expansion coefficient by changing the Zr/Ti composition and the substrates, using HRTEM and XRD methods. XTEM analysis showed that usual lamella configuration of 90° domains of 8–30nm in width penetrated the columnar grain and the PZT layer in the PZT stacked film of Zr/Ti=20/80, 30/70, 40/60. On the other hand, the close-packed 90° domains of 4–5nm in width existed in a epitaxial columnar grain in the PZT50/50 stacked film. The P-E hysteresis loops of PZT20/80 stacked films deposited on STO and Si substrates show the remanent polarization of 2Pr=136μC/cm2, 2Pr=80μC/cm2, respectively. On the other hands, those of PZT50/50 stacked films deposited on STO and Si substrates show the polarization of 2Pr=125μC/cm2, 2Pr=36μC/cm2, respectively. Thus, the P-E hysteresis loop of PZT50/50 has remarkable difference of 2Pr between the substrates.
Sm Doping Effects on Electrical Properties of Sol-Gel Derived SrBi2Ta2O9 Films
Authors: Tokumitsu Eisuke , Kishi Masahito 
Published: April 2011

ABSTRACTWe have characterized (Sr,Sm)Bi2Ta2O9 (SSBT) films fabricated by the sol-gel technique on Pt/Ti/SiO2/Si substrates. For ferroelectric-gate FET applications, a ferroelectric film which has a small remanent polarization and a relatively large coercive field is required. It is demonstrated that Sm doping in ferroelectric SBT films is effective to reduce the remanent polarization and enhance the coercive field. Sr0.5Sm0.2Bi2.2Ta2O9 films (150nm) crystallized at 850°C exhibits good electrical properties with a remanent polarization of 1.7 μC/cm2 and a coercive fields of 85 kV/cm. These values are suitable for ferroelectric-gate FET applications.
MFIS and MFS structures using SrBi2Ta2O9 thin films for the FRAM applications
Authors: Victor P. , Bhattacharyya S. , Saha S. , Krupanidhi S. B. 
Published: April 2011

ABSTRACTRecently there is an increasing demand and extensive research on high density memories, in particular to the ferroelectric random access memory composed of 1T/1C (1 transistor/1 capacitor) or 2T/2C. FRAM's exhibit fast random acess in read/write mode, non - volatility and low power for good performance. An integration of the ferroelectric on Si is the key importance and in this regard, there had been various models proposed like MFS, MFIS, MFMIS structure etc., Choosing the proper insulator is very essential for the better performance of the device and to exhibit excellent electrical characteristics. ZrTiO4 is a potential candidate because of its excellent thermal stability and lattice match on the Si substrate. SrBi2Ta2O9 and ZrTiO4 thin films were prepared on p - type Si substrate by pulsed excimer laser ablation technique. Optimization of both ZT and SBT thin films in MFS and MFIS structure had been done based on the annealing, oxygen partial pressures and substrate temperatures to have proper texture of the thin films. The dc leakage current, P - E hysteresis, capacitance - voltage and conductance - voltage measurement were carried out. The effect of the frequency dependence on MFIS structure was observed in the C – V curve. It displays a transition of C - V curve from high frequency to low frequency curve on subjection to varied frequencies. Density of interface states has been calculated using Terman and high - low frequency C - V curve. The effect of memory window in the C - V hysteresis were analysed in terms of film thickness and annealing temperatures. DC conduction mechanism were analysed in terms of poole - frenkel, Schottky and space charge limited conduction separately on MFS, MIS structure.
•• Recent Progress in Ferroelectic-gate FETs
Authors: Ishiwara Hiroshi , Park Byung-Eun 
Published: April 2011

ABSTRACTRecent progress in the research of ferroelectric-gate FETs is reviewed mainly from a view-point of the data retention characteristics. First, importance of insulator-inserted gate structures such as an MFIS (M; metal, F; ferroelectric, I; insulator, S; semiconductor) or MFMIS structure is described and the necessary conditions for the insulating buffer layer and the ferroelectric film are discussed. Then, experimental results for the SiO2 and high-k dielectric buffer layers combined with such ferroelectric films as SBT (SrBi2Ta2O9) and BLT ((Bi,La)4Ti3O12) are presented, in which particular attention is paid to the discussion on the induced charge matching between the buffer layer and the ferroelectric film. As an example, it is shown in a Pt/BLT/LaAlO3/Si diode that the high and low capacitance values written by positive and negative pulses can be retained at least for 3 days. Finally, recent experimental results on the data retention characteristics of the ferroelectric-gate FETs are presented.
Bilinear Behavior in the Indentation Size Effect: A Consequence of Strain Gradient Plasticity
Authors: Elmustafa A. A. , Lou J. , Adewoye O. , Soboyejo W. O. , Stone D. S. 
Published: April 2011

ABSTRACTThis paper examines the effects of stacking fault energy on the micro- and nano-indentation behavior of face-centered-cubic thin films. These include: LIGA nickel MEMS structures, alpha brass, copper and high purity aluminum. The measured hardness are then fitted to a strain gradient plasticity model based on the Taylor dislocation hardening model. Hardness is shown to exhibit a size dependence with different characteristic slopes in the micron and nano-scale regimes. Deep indents are shown to exhibit classical linear behavior. However, shallow indents exhibit an abrupt decrease in slope (almost by a factor of 10), giving rise to a bi-linear behavior. Furthermore, as the gradients become less sharp, the trends in the nano-hardness data become similar to those of the microhardness data predicted by the strain gradient plasticity model. Finally, the effects of stacking fault energy are then discussed within the context of cross-slip and hardening associated with Shockly partials.
Thermal Stability of Nanocrystalline Diamond Films Grown by Microwave Plasma Chemical Vapor Deposition
Authors: Bulut Mevlut , Catledge Shane A. , Vohra Yogesh K. , Camata Renato P. 
Published: April 2011

ABSTRACTIn this work, the open-air thermal stability of nanocrystalline diamond films grown on mirror-polished titanium alloy substrates by the Microwave Plasma Chemical Vapor Deposition (MPCVD) technique was studied. The results of this investigation show that nanocrystalline diamond films are highly stable in air up to 600°C with no significant change in mechanical properties. Samples annealed between 600°C and 650°C, however, exhibit values of hardness lower by as much as 40% compared to as-grown samples. Above 650°C serious delamination effects were observed in the coatings.
Structural Investigation of Alumina Thin Films Deposited by Chemical Vapor Deposition
Authors: Bahlawane Naoufal , Blittersdorf Sabine , Kohse-Höinghaus Katharina , Atakan Burak , Müller Jürgen 
Published: April 2011

ABSTRACTThe present study concerns the deposition of α–Al2O3 for diffusion barrier applications on superalloy substrates. The growth of α–Al2O3 has been achieved by chemical vapor deposition (CVD) using an AlCl3/CO2/H2 gas mixture at 1080 °C. Among several growth-controlling parameters with potential importance for the whisker growth process, the reactor pressure during deposition seems to be highly influential on the resulting film structure. Deposited films at low pressure presented solely a fine whisker structure. This non-closed structure is not suitable as diffusion barrier; however, the observed high porosity makes the deposit a potential candidate as a catalysis support. An increase of the deposition pressure led to a competitive growth of whiskers and grains. A suitable microstructure was attained at relatively high pressure (100 mbar) where the surface was fully covered by 2 μm large alumina crystals that formed a closed structure. Further increase of the pressure led to an irregular and rough surface microstructure.
Structure and Electrical Properties of Pulsed Laser Deposited Amorphous Carbon Nitride Thin Films
Authors: Aoi Yoshifumi , Ono Kojiro , Sakurada Kunio , Kamijo Eiji 
Published: April 2011

ABSTRACTAmorphous CNx thin films were deposited by pulsed laser deposition (PLD) combined with a nitrogen rf radical beam source which supplies active nitrogen species to the growing film surface. The deposited films were characterized by X-ray photoelectron spectroscopy (XPS), Raman scattering, and Fourier transform infrared (FTIR) spectroscopy. Nitrogen content of the deposited films increased with increasing rf input power and N2 pressure in the PLD chamber. The maximum N/C ratio 0.23 was obtained at 400 W of rf input power and 1.3 Pa. XPS N 1s spectra shows the existence of several bonding structures in the deposited films. Electrical properties of the deposited films were investigated. The electrical conductivity decreased with increasing N/C atomic ratio. Temperature dependence of electrical conductivity measurements indicated that electronic conduction occurred by variable-range hopping between p electron localized states.
Reactive Sputtering of Nanostructured WCx
Authors: Rumaiz Abdul K , Ismat Shah S. , Ni C. , Derek Demaree J. , Hirvonen J. K. 
Published: April 2011

ABSTRACTNanostructured WCx thin films were reactively sputtered in argon-methane plasma. A DC planar magnetron with a pure tungsten target was used. Films were deposited on glass, quartz, silicon and sapphire substrates at temperatures up to 700 °C. The carbon content in the film was varied by changing the partial pressure of methane. The carbon content in the films was analyzed by using X-ray Photon Spectroscopy (XPS) and Rutherford Backscattering Spectroscopy (RBS).The effect of temperature on the grain size was studied using Transmission Electron Microscopy (TEM). The target poisoning behavior was studied by measuring the target current. The critical methane concentration at which the metal – poison mode transition occurs was measured to be around 42% of CH4 in Ar. This transition is characterized by a sharp fall in the target current. The hysteresis in the target current can also be attributed to target poisoning. In this paper we describe the effects of film growth parameters on the film composition. We also discuss an alternate sputtering technique, hollow cathode sputtering, and the advantages of this technique over the conventional planar magnetron technique.
Properties Oftetrahedralamorphous Carbon Films Deposited By the Filtered Cathodicarc Method
Authors: Nagata Naruhisa , Kusakawa Kazuhiro , Kumagai Akiyasu , Matsuyama Hideaki 
Published: April 2011

ABSTRACTFirst, we studied the relation between the sp3 bond ratio and the hardness of 100-nm-thick tetrahedral amorphous carbon (ta-C) films deposited by a Filtered Cathodic Arc (FCA) system at different substrate bias voltages. For comparison, sputtered amorphous carbon (a-C) films and Highly Oriented Pyrolytic Graphite (HOPG) were also analyzed. According to the results, ta-C film deposited at a -70 volt substrate bias voltage had high hardness and high sp3 bond ratio of up to 88 GPa and 85%, respectively, whereas those of sputtered a-C were 29 GPa and 28%. Furthermore, we found that the hardness of carbon films, including sputtered a-C and HOPG, increased with increasing sp3 bond ratio. Based on this relation, the chemical bond structures of carbon films are considered to be closely related to their mechanical properties. Secondly, we investigated the relation between sp3 bond ratio and ta-C film thickness, over the range from 1 to 10 nm. The measurements showed that a 2-nm-thick initial layer grown on the surface of CoCrPt magnetic film had low sp3 bond ratios. It is suggested that this reduction in sp3 bond ratio in the initially grown layer seriously degrades the film's performance as a hard disk media overcoat. Further efforts to improve ta-C film processing will be required to improve its mechanical properties.
Towards an improvement of performance of TiAlN hard coatings using metal interlayers
Authors: Castanho J. M. , Vieira M. T. 
Published: April 2011

ABSTRACTTiAlN sputtered coatings have been used with success in high-speed cutting tools in the last few years. However, the adhesive failures of the coatings refrain its application in more severe wear conditions like as high-speed machining. The assumptions for the present research were based on the hypothesis that thin metal interlayers will behave as shear stress sinkers, which could decrease the delamination of the thin films. In the present work, coatings of TiAlN with thin ductile metallic interlayers (Al, Ti, Cu and Ag) were deposited by reactive d.c. magnetron sputtering. Multilayer coatings with aluminum, titanium and silver interlayers achieve higher adhesion values (70N) than TiAlN monolithic coating (40N). Three and five metal ductile layers contribute to an increase of hardness and Young's modulus without change the residual stresses of the monolithic coating. Contrarily, the introduction of copper layers reduces all the studied mechanical properties of the TiAlN monolithic coatings, which are related to the different deformation mechanisms of the ductile interlayers.
Structural and Tribological Properties of Molybdenum Disulfide/Metal Multilayered Films Deposited by Pulsed Laser Deposition
Authors: Phani A. R. , Krzanowski J. E. , Nainaparampil J. J. 
Published: April 2011

ABSTRACTThe structural, mechanical and tribological properties of MoS2/metal and MoS2/carbide multilayer thin films have been examined in this study. The films were deposited by pulsed laser deposition of sequential layers of MoS2 and either Ti, Cr or TiC. The compositions of the films were analyzed by wavelength dispersive spectroscopy (WDS) and confirmed the presence of the deposited elements. X-ray diffraction and cross-section SEM methods were employed to characterize the films. The XRD results did not reveal the presence of separate Ti, Cr or TiC phases, and the SEM did not show any multilayer structures. From these results, it was concluded that the added metal or carbide elements are present as either a dispersed nano-structured phase or in solid solution with the MoS2. Nonetheless, friction and wear testing showed dramatic improvements over MoS2 films when tested in a humid (45% r/h) environment.
Atomic-Scale Dynamic Deformation Behavior of BN Thin Films
Authors: Iwamoto Chihiro , Yang Hangsheng , Yoshida Toyonobu 
Published: April 2011

ABSTRACTDeformation behavior of the BN film was dynamically observed by high-resolution transmission electron microscopy. BN thin films were deposited on a narrow edge of Si flakes, using inductively coupled plasma-enhanced chemical vapor deposition. High-resolution observation of the sample revealed that the BN film was possibly deposited on the edge of the Si thinned to less than 10 nm in thickness, whose morphology varied depending on the thickness of the Si edge. Intriguing mechanical properties of the BN films, especially relating their dynamic behavior, were clearly verified by the high-resolution observation with piezo-ceramic tube for three-axis positioning of an indenter.