bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dielectric and Piezoelectric Properties of PZT 52/48 Thick Films with (100) and Random Crystallorgraphic Orientation
Authors: Zhou Q. F. , Hong E. , Wolf R. , Trolier-McKinstry S. 
Published: April 2011

AbstractFerroelectric Pb(Zr1划xTix)O3 (PZT) films have been extensively studied for active components in microelectromechanical systems. The properties of PZT films depend on many parameters, including composition, orientation, film thickness and microstructure. In this study, the effects of crystallographic orientation on the dielectric and transverse piezoelectric properties of Pb(Zr0.52Ti0.48)O3 (PZT 52/48) films are reported. Crack free random and highly (100) oriented PZT(52/48) films up to ∼ 7 μm thick were deposited using a sol-gel process on Pt (111)/Ti/SiO2/Si and Pt(100)/SiO2/Si substrates, respectively. The dielectric permittivity (at 1kHz) for the (100) oriented films was 980-1000, and for the random films ∼ 930-950. In both cases, tanä was less than 0.03. The remanent polarization (∼ 30 μC/cm2) of random PZT films was larger than that of (100) oriented PZT films. The transverse piezoelectric coefficient (d31(eff)) of PZT films was measured by the wafer flexure method. The d31(eff) coefficient of random PZT thick films (-80pC/N) was larger than that of (100) oriented films (-60pC/N) when poled at 80 kV/cm for 15 min.
Hydrothermal Fabrication of Barium Strontium Titanate Ceramics for High-Frequency Wireless Communication Networks
Authors: Zelonka K. , Sayer M. , Hammad H. , Freundorfer A.P. 
Published: April 2011

AbstractThin films of barium strontium titanate are fabricated on alumina by a hydrothermal method. Crystalline films are produced at temperatures as low as 60°C. The relative dielectric permittivity of films with the composition Ba0.15Sr0.85TiO3 lies in the range between 150 and 220 for low frequencies (100 kHz to 1 MHz), decreasing with frequency. The loss tangent for the films increases from 0.05 to 0.15 over the same frequency range. Relative concentrations of barium and strontium in the film are controllable through the hydrothermal reaction conditions. The surface microstructure of the films is examined.
Oxide Films for Integrated Capacitors in Thin Film Functional Modules
Authors: Klee M. , Wissen D. , Keur W. , Kiewitt R. , Bausen D. , Lok P. 
Published: April 2011

AbstractSingle oxide films as well as complex oxide films are intensively studied for multi-chip modules with integrated passive functions. In this paper the processing and properties of oxide films such as Ta2O5, TiO2, Nb2O5, Ta2O5 -Al2O3, Ta2O5–Nb2O5 as well as complex oxide films such as BiNbO4 and Ba1划xSrxTiO3 films will be discussed with respect to their integration into thin film functional modules.
Theoretical and Experimental Studies on Retention Characteristics of Metal-Ferroelectric-Insulator-Semiconductor and Metal-Insulator -Ferroelectric-Insulator-Semiconductor Structures
Authors: Okuyama Masanori , Takahashi Mitsue , Kodama Kazushi , Nakaiso Toshiyuki , Noda Minoru 
Published: April 2011

AbstractRetention characteristics of Metal-Ferroelectric-Insulator-Semiconductor(MFIS) and Metal-Insulator-Ferroelectric-Insulator-Semiconductor(M-I-FIS) structures have been investigated both theoretically and experimentally. The simulated time dependence of capacitance for the MFIS has indicated that reducing currents through the ferroelectric and the insulator layers improves the retention characteristics more effectively than choosing the insulators with larger dielectric constants. The M-I-FIS structure has been studied in order to reduce the charge injection between the metal and the ferroelectric layer in the MFIS. The simulations have indicated that the M-I-FIS can provide much longer retention time than the original MFIS, although the experimental retention time of the M-I-FIS have almost the same as that of the MFIS.
Microstructural and Electrical Properties of La Doped Ba1划xSrxTiO3 Thin Films For Tunable Microwave Device Applications
Authors: Cole M.W. , Joshi P.C. , Ngo E. , Hubbard C.W. , Lee U. , Ervin M.H. 
Published: April 2011

AbstractWe have investigated the structural, compositional, interfacial, surface morphological and dielectric properties of Ba0.6Sr0.4TiO3 solid solution thin films La doped from 0 to 10 mol%. The doped thin films were prepared by the metalorganic solution deposition technique using carboxylate-alkoxide precursors. After post-deposition annealing in oxygen ambient at 750 °C the films were characterized via x-ray diffraction, Auger electron microscopy, field emission scanning electron microscopy, and atomic force microscopy. The electrical measurements were achieved in the metal-insulator-metal (MIM) configuration with Pt as the top and bottom electrode. Our results demonstrated that La doping had a strong effect on the films microstructural, dielectric and insulating properties. Specifically, 1 mol% La doped BST films exhibited a lower dielectric constant, 283 and higher resistivity 31.4×1013 W-cm with respect to that of undoped BST. The loss tangent and tunability (at 100 kHz) of the 1 mol% La doped BST films were 0.019 and 21% (at E=300kV/cm) respectively.
Electrodes and Barriers for Dram and Feram: Processing, Integration, and Fundamentals
Authors: Saenger K.L. , Andricacos P.C. , Athavale S.D. , Baniecki J.D. , Cabral C. , Costrini G. , Kwietniak K.T. , Laibowitz R.B. , Lian J.J. , Limb Y. , Neumayer D.A. , Wise M.L. 
Published: April 2011

AbstractMaterials requirements for electrodes and barriers in high density dynamic random access memory (DRAM) and ferroelectric random access memory (FERAM) are reviewed, and some approaches to barrier materials and device geometries are described. Electrode/barrier topics covered in more detail include Pt reactivity with Si-containing barriers and dielectric overlayers, the application of a Bragg-Brentano x-ray diffraction technique to quantitatively probe Pt and Ir electrode morphology and thickness changes during ferroelectric processing, the stability of metal oxide electrode materials in reducing ambients, electrode patterning techniques (including Pt electroplating), and electrical properties of 3-D capacitors in 256k arrays as a function of top electrode annealing treatments.
200 °C Preparation of SiNx Passivation Films for PZT Ferroelectric Capacitors by Catalytic CVD
Authors: Minamikawa Toshiharu , Yonezawa Yasuto , Fujimori Yoshikazu , Nakamura Takashi , Masuda Atsushi , Matsumura Hideki 
Published: April 2011

AbstractFeasibility of SiNx passivation films at low substrate temperatures prepared by catalytic chemical vapor deposition (Cat-CVD) is studied for ferroelectric nonvolatile random access memories (FRAMs). SiNx films were prepared at low substrate temperatures of 100 °C, 175 °C and 200 °C using Cat-CVD. Adjusting on flow rate ratio of SiH4/NH3, the refractive index of SiNx film, deposited at 175 °C and 200 °C, measured by ellipsometry is controlled around 2.0. SiNx films, with the refractive index around 2.0, deposited at only 200 °C show the following properties. 1) No oxidation during air exposure for 3 months was observed for the films. 2) Etching rate of the films in buffered HF is 20 nm/min. The dense SiNx film, which is resistive for oxidation in air exposure and dissolution in buffered HF, is prepared at 200 °C and the film is suitable to the passivation of ferroelectric capacitors.
Highly Stable Ir-Ta-O Electrode for Ferroelectric Material Deposition
Authors: Zhang Fengyan , Hsu Sheng Teng , Maa Jer-shen , Ono Yoshi , Hong Ying , Zhuang Weiwei , Ohnishi Shigeo , Zhen Wendong , Fujiwara Norito 
Published: April 2011

AbstractIr-Ta-O composite bottom electrode has extraordinary high temperature stability. It can maintain good conductivity and integrity even after 5min annealing at 1000 °C in oxygen ambient. The thermal stability of Ir-Ta-O on different substrates has been studied. It shows that Ir-Ta-O is also very stable on Si and SiO2 substrates. No hillock formation and peelings of the bottom electrode were observed after high temperature and long time annealing in O2 ambient. SEM, TEM, XRD, and AES have been used to characterize the Ir-Ta-O film and the interfaces between Ir-Ta-O bottom electrode and Si or SiO2 substrate. The composition and conductivity changes of the electrode during oxygen ambient annealing and the interdiffusion issue will be discussed. Furthermore, Ir-Ta-O/SiO2/Si capacitor with 30Å gate oxide was fabricated and the C-V and I-V characteristics were measured to confirm the stability of Ir-Ta-O on thin gate oxide.
Degradation of Ferroelectric Pb(Zr,Ti)O3 Under Reducing Conditions
Authors: Shimakawa Yuichi , Kubo Yoshimi 
Published: April 2011

AbstractThe degradation mechanism of Pb(Zr,Ti)O3 (PZT) under reducing conditions was revealed. In contrast to the significant decrease in the sample weight of SrBi2Ta2O9 due to decomposition, the weight of Pb(Zr,Ti)O3 samples change little during H2-annealing at typical process temperatures. Although no apparent changes were detected by thermogravimetric and x-ray diffraction measurements after annealing, the PZT material did actually change. The main mechanism of the degradation is introduction of oxygen defects into the materials. The oxygen defects produce a donor level within the band gap, and light absorption by this donor level accounts for the change in sample appearance from white to black. Different endurance behaviors of materials against reducing conditions were also found: PbZrO3 decomposes through oxygen dissociation more easily than PbTiO3. Oxygen atoms in PbZrO3 are more weakly bonded to Zr than to Ti in PbTiO3 because of a significant anti-bonding component in the hybridized orbitals.
The Properties of Mfmos and MFOS Capacitors with High K Gate Oxides for one Transistor Memory Applications
Authors: Li Tingkai , Hsu Sheng Teng , Ying Hong , Ulrich Bruce 
Published: April 2011

AbstractMFMOS and MFOS (M: Metal, F: Ferroelectrics, O: Oxide, S: Silicon) capacitors with high k gate oxides, such as ZrO2, HfO2 thin films, have been fabricated for one transistor memory applications. Experimental results showed that ZrO2 and HfO2 have no serious reaction or diffusion into silicon substrate. Due to their high dielectric constant, the operation voltages of MFMOS capacitors are reduced. The MFMOS capacitor exhibits 2V memory window. For lead germanium oxide (PGO) on ZrO2 and PGO on HfO2 MFOS memory cells the memory windows are 1.8 V and 1.6 V, respectively, which are large enough for one-transistor memory applications. The basic mechanism for one-transistor memory applications was also discussed.
Investigation of Dead Layer Thickness in SrRuO3/Ba0.5Sr0.5TiO3/Au Thin Film Capacitors
Authors: Sinnamon L. J. , Bowman R. M. , Gregg J. M. 
Published: April 2011

AbstractThin film capacitors with barium strontium titanate (BST) dielectric layers of 7.5 to 950 nm were fabricated by Pulsed Laser Deposition. XRD and EDX analyses confirmed a strongly oriented BST cubic perovskite phase with the desired cation stoichiometry. Room temperature frequency dispersion (ε100 kHz / ε100 Hz) for all capacitors was greater than 0.75. Absolute values for the dielectric constant were slightly lower than expected. This was attributed to the use of Au top electrodes since the same sample showed up to a threefold increase in dielectric constant when Pt was used in place of Au. Dielectric constant as a function of thicknesses greater than 70 nm, was fitted using the series capacitor model. The large interfacial parameter ratio di / εi of 0.40 ± 0.05 nm implied a significant dead-layer component within the capacitor structure. Modelled consideration of the dielectric behaviour for BST films, whose total thickness was below that of the dead layer, predicted anomalies in the plots of d/ ε against d at the dead layer thickness. For the SRO/BST/Au system studied, no anomaly was observed. Therefore, either (i) 7.5 nm is an upper limit for the total dead layer thickness in this system, or (ii) dielectric collapse is not associated with a distinct interfacial dead layer, and is instead due to a through-film effect.
Characterization of Conductive RuO2 Thin Film as Bottom electrodes for Ferroelectric Thin Films
Authors: Bhaskar S. , Dobal P. S. , Majumder S. B. , Katiyar R. S. 
Published: April 2011

AbstractRuthenium Oxide (RuO2) thin films were prepared on silicon substrates by solution chemistry technique. X-ray Diffraction (XRD), Atomic Force Microscopy (AFM), micro-Raman, X-ray photoelectron spectroscopy (XPS), and four probe Van-der-paw technique were used for the film characterization. X-ray analysis shows a rutile structure in these films. The films annealed at 700°C showed lowest resistivity of 29 × 10−5 ohm-cm. The presence of Eg, A1g, and B2g modes is consistent with the Raman spectrum of rutile phase. These modes as well as additional unidentified band at about 477 cm−1 were investigated by temperature dependent Raman studies. Based on the result, band at 477 cm−1 that disappears above 370 K is attributed to hydrated RuO2 present in the films. XPS analysis show stoichiometric rutile RuO2 present in the films. Small concentrations of RuCl3, RuO3 and hydrated RuO2 were also detected. Pb0.9La0.15TiO3 (PLT15) thin films were deposited on RuO2/Si substrates and characterized for its ferroelectric properties to demonstrate that solution deposition technique offers an alternative approach for preparing high quality RuO2 bottom electrodes.
Properties of Au/Pb(Zr0.52Ti0.48)O3/ Bi4Ti3O12/p-Si Ferroelectric Memory Diodes
Authors: Yu Jun , Wang Hua , Dong Xiaomin , Zhou Wenli , Wang Yunbo , Zhu Lili 
Published: April 2011

AbstractA ferroelectric memory diodes that consists of Au/Pb(Zr0.52Ti0.48)O3/Bi4Ti3O12/p-Si multilayer configuration was fabricated by pulsed laser deposition (PLD) technique. The ferroelectric properties and the electrical characteristics of the ferroelectric film system were investigated. The polarization-voltage curve of Pb(Zr0.52Ti0.48)O3/Bi4Ti3O12 thin films system had an asymmetry hysteresis loop with Pr=20μC/cm2 and Ec=48 kV/cm, and the decay in remnant polarization was only 10% after 109 switching cycles. The C-V curve and the I-V curve showed memory effects derived from the ferroelectric polarization of PZT/BIT films. The current density was 6.7×10−8A/cm2 at a voltage of +4V, and the conductivity behavior is discussed. The results suggested that the growth of the BIT ferroelectric layer is helpful to good ferroelectric properties, fatigue and capacitance retention characteristics.
The Effect of Forming Gas Annealing on Pt/(Ba,Sr)TiO3/Pt Thin Film Capacitors for Future Dram Applications: Electrical Properties and Degradation Mechanisms
Authors: Baniecki J. D. , Parks C. , Laibowitz R.B. , Shaw T. M. , Lian J. 
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 Pt/Ba0.7Sr0.3TiO3/Pt thin film capacitors after forming gas exposure. Deuterium SIMS depth profiling shows that high deuterium concentrations can be incorporated into Pt/BSTO/Pt capacitors after forming gas annealing. The increase in H/D concentration in the film is accompanied by an increase in the leakage and dielectric relaxation current density. Voltage offsets in the capacitance-applied voltage (C-VA) characteristics after forming gas exposure at lower temperatures (20 °C) and a suppression in the capacitance density near zero applied D.C. bias after forming gas exposure at higher temperatures, suggests that one effect of forming gas exposure to Pt/BSTO/Pt thin film capacitors is to introduce positive space charge into the BSTO film. Using an equivalent model for a ferroelectric thin film capacitor, which incorporates lower permittivity interfacial layers and a nonlinear electric field-electric displacement relationship for the film interior, the effects of a uniform distribution of positive space charge on the theoretical C-VA and current density applied voltage (J-VA) characteristics are investigated. It is shown the model can account for many of the observed changes that occur in the experimental C-VA and J-VA characteristics after forming gas exposure.
Room Temperature ZnO/Zn0.8Mg0.2O Resonant Tunneling Devices For Microwave Applications
Authors: Inumpudi Aravind , Iliadis Agis A. , Choopun Supab , Vispute R. D. , Venkatesan T. 
Published: April 2011

ABSTRACTA ZnO/Zn0.8Mg0.2O double barrier resonant tunneling device (DBRTD) is reported here for the first time. The structure consists of 6 nm ZnO quantum wells and 7 nm Zn0.8Mg0.2O barriers grown by pulsed laser deposition (PLD) on c-cut sapphire substrates. Negative differential resistance (NDR) peaks were obtained at room temperature. The structure is developed by using an indium-tin oxide (ITO) layer both as the back contact electrode and as an etch-stopping layer. The PLD growth quality, wet etching processing for developing the mesa structure, and the I-V characteristics of the device are reported.
Ferroelectric Na0.5K0.5NbO3 Films for Voltage Tunable Microwave Devices
Authors: Cho Choong-Rae , Grishin Alex , Andrèasson Johanna , Lindbäck Ture , Abadei Saeed , Gevorgian Spartak 
Published: April 2011

ABSTRACTSingle phase Na0.5K0.5NbO3 (NKN) thin films have been pulsed laser deposited on Al2O3(0112), LaAlO3(001), and MgO(001) single crystal substrates as well as on the SiO2/Si(001) wafers to demonstrate films feasibility for voltage tunable microwave device applications. NKN film texture has been found to be quite different on three different single crystals: highly c-axis oriented on Al2O3, “cube-on-cube” epitaxial quality on LaAlO3, bi-axial textures on MgO, while NKN films grown on Si substrate with various thickness of SiO2 buffer layer possess highly c-axis oriented quadrupled structure. NKN film interdigital capacitors fabricated onto single crystal oxide substrates showed tunability of 30-40 % and dissipation factor of 0.01-0.02 at 1 MHz and applied electric field of 100kV/cm. Microwave frequency measurements for NKN/Si varactors yield 13 % tunability and dielectric loss tanδ as low as 0.012 at 40 GHz under 200 kV/cm applied bias.
Characteristics of Microwave Absorption of Ni-Zn-Ferrite/Sic Hemi-Crystallized Composites
Authors: Nakanishi Makoto , Shibuya Tomonori , Fujii Tatsuo , Takada Jun 
Published: April 2011

ABSTRACTIn order to develop wide-band microwave absorbers we tried to prepare composite absorbers between the magnetic loss (Ni-Zn-ferrite) and the dielectric loss (SiC) materials. The dry or wet mixtures of Ni-Zn-ferrite and polycarbosilane (PCS) were cured in air and were then subjected to pyrolysis forming of the ferrite composites. The composites produced by the wet mixing had granular structure: the PCS surrounding the ferrite particles suppressed the sintering and the grain growth of the ferrite composites during pyrolysis. The matching frequency due to the magnetic loss linearly increased with increasing the PCS content. Moreover the ferrite/SiC hemi-crystallized composite cured at 473 K for 24 hours showed wide-band absorption spectrum having the both magnetic and dielectric losses.
Processing and Characterization of Pure and Doped Ba0.6Sr0.4TiO3 Thin Films for Tunable Microwave Applications
Authors: Joshi P. C. , Cole M. W. , Ngo E. , Hubbard C. W. 
Published: April 2011

ABSTRACTBa1−xSrxTiO3 thin films are being developed for high-density DRAM devices. The nonlinearity of its dielectric properties with respect to applied dc voltage makes it attractive for tunable microwave devices. For successful integration into microwave devices, extremely reliable Ba1−xSrxTiO3 thin films with enhanced dielectric and insulating properties are desired. Properties of Ba1−xSrxTiO3are typically varied by changing the Ba/Sr ratio and/or doping. In this paper, we reports on the effects of acceptor and donor doping on the microstructural and electrical properties of Ba0.6Sr0.4TiO3 (BST) thin films deposited by metalorganic solution deposition technique on platinum coated silicon substrates. The effects of doping on structure, dielectric permittivity, dielectric loss tangent, and leakage current have been analyzed. The structure of the films was analyzed by x-ray diffraction (XRD). The surface morphology of the films was examined by field emission scanning electron microscope (FESEM) and atomic force microscope (AFM). The electrical measurements were conducted on MIM capacitors using Pt as the top and bottom electrode. It was possible to significantly improve the dielectric loss and leakage current characteristics, and control the dielectric tunability by doping the BST thin films.
Temperature-Dependent Internal Friction in Silicon Nanoelectromechanical Systems
Authors: Evoy Stephane , Olkhovets Anatoli , Carr Dustin W. , Parpia Jeevak M. , Craighead Harold G. 
Published: April 2011

ABSTRACTThe mechanical properties of micro- and nanomechanical systems are of interest from both fundamental and technological standpoints. High-frequency mechanical resonators presenting high quality factors are of interest for the development of sensitive force detecting devices, and highly efficient RF electromechanical filters and oscillators. Internal losses are the combination of both extrinsic and intrinsic issues that must be well understood for the optimization of resonator quality, and for the experimental access to fundamental nanoscopic mechanical phenomena. The temperature dependent internal friction in 1-10 MHz paddle oscillators is reported. Quality factors as high as 1000 and 2500 are observed at room temperature in metallized and non-metallized devices, respectively. Internal friction peaks are observed in all devices in the T = 160-180 K range. The position of those peaks is consistent with the Debye relaxation of previously reported surface and near-surface phenomena.
On the Fracture Toughness of Polysilicon MEMS Structures
Authors: Kahn H. , Ballarini R. , Heuer A.H. 
Published: April 2011

ABSTRACTThe mechanical properties of micromachined polysilicon are of great interest to designers of microelectromechanical systems (MEMS) devices. Numerous investigations have been carried out to determine the strength of MEMS-fabricated polysilicon structures, and the experimental results vary widely, depending on the experimental techniques, specimen geometries, and processing conditions. In order to determine whether these variations are inherent to all mechanical properties of MEMS materials, the fracture toughness, Kcrit, of micromachined polysilicon has been investigated, using a wide range of material microstructures (microstructure is used here in the Materials Science sense to mean the grain structure visible in a microscope, and not in the MEMS sense to mean small structures). Since fracture toughness is a fundamental materials property, whether or not it varies with microstructure and processing is an interesting question. We have confirmed that Kcrit is not a microstructure-sensitive property, using surface-micromachined specimens with sharp pre-cracks which are integrated with electrostatic actuators. The measured Kcrit is 1.0±0.1 MPa √m for a wide range of miscrostructures.
The Influence of Fabrication Governed Surface Conditions on the Mechanical Strength of Thin Film Materials
Authors: Chasiotis Ioannis , Knauss Wolfgang G. 
Published: April 2011

ABSTRACTThe mechanical strength of thin polysilicon films has been examined in connection with exposure to Hydrofluoric Acid (HF). It is found that surface roughness as characterized by groove formation at grain boundaries depends on the HF release time. Surface undulations and crevasses related to grain structure result in reduced fracture strength and induced errors into the effective elastic modulus measurements - especially when the latter is determined from flexure configurations. Extensive exposure to HF results in material degradation, as evidenced by a transition from a transgranular to an intergranular failure manner and a corresponding drastic drop of the film strength with attendant increase of porosity.