bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fe2O3:SnO2 Nanostructured System as Semiconductor Gas Sensor Material
Authors: Arbiol J. , Morante J. R. , Rumyantseva M. , Kovalenko V. , Gaskov A. 
Published: April 2011

ABSTRACTIn the present work, we report a detailed study based on transmission electron microscopy of the microstructure and composition of the Fe2O3: SnO2 nanometrical binary system obtained by sol-gel. We studied a set of samples based in a pure Fe2O3 material where we added SnO 2 from 0 to 50% Sn-Fe nominal content. The structure of our composites will change from pure a-Fe2O3 to the well-known cassiterite SnO 2 structure for high Sn content. Distortions on the structural parameters will be attributed to the presence Sn4+ ions on the α-Fe2O3 structure and Fe3+ ions on the SnO2 cassiterite structure.
Formation of Porous Silicon Layers on Insulating Substrate for Microbridge – Type Sensor Applications
Authors: Andrushin Sergey Ya. , Balagurov Leonid A. , Bayliss Sue C. , Liberova Galina V. , Petrova Elena A. , Unal Bayram , Yarkin Dmitrii G. 
Published: April 2011

ABSTRACTFormation processes of porous silicon on insulating substrate were studied. It was demonstrated that both electrochemical and chemical formation methods allow to transform heavily doped p-type polycrystalline silicon into homogeneous porous silicon. Porous silicon was successfully used as sacrificial layer in the fabrication process of microbridge structures.
Electronic Detection of Nucleic Acid Molecules with a Field-Effect Transistor
Authors: Ingebrandt Sven , Han Yinhua , Sakkari Malla-Reddy , Stockmann Regina , Belinskyy Oleksandr , Offenhäusser Andreas 
Published: April 2011

ABSTRACTCurrently, systems for the detection of nucleic acid sequences, known as DNA-chips, are getting lots of attention. Such systems usually involve either an enzymatic or chemical labelling reaction as part of the detection process. The next generation of DNA-chips aims at a labelfree, fully electronic readout system. Several new approaches to signal generation that avoid a labelling step have been developed in recent years. Besides other surface sensitive measurements the possibility of electrochemical impedance and field-effect measurements for the detection of biomolecules have been discussed. The fully electronic detection of charged biomolecules based on the field-effect principle offers a labelfree method, which combines the unique sensitivity and selectivity of biomolecular recognition reactions with an electronic chip-based readout. In this approach one type of molecules is fixed at a surface and the biomolecular reaction with complementary molecules is detected by change in the drain-source current of the transistor. This change can occur by a change of the interface capacitance of the transistor gate or by change of the surface potential during adsorption of the molecules. At the moment a complete theoretical description of the detection principle is still under discussion. However, the fully electronic readout of biomolecular reactions offers a unique principle for the construction of many different sensors for bioassays. We are working on an approach to detect the hybridization of DNA sequences using electrolyte-oxide-semiconductor field-effect transistor (EOSFET) arrays. This method allows direct and in situ detection of specific DNA sequences without any labelling.
Micro Sensor Operating at Room Temperature
Authors: Duk Song-Kap , Lee Duk-Dong 
Published: April 2011

ABSTRACTIn the study, low power micro gas sensors operated at room temperature for the detection of NH3 and NOx gases are proposed. As candidate material of gas sensor for NH3 gas detection at room temperature, polyaniline(PANi) synthesized by chemical polymerization was selected. And Te(Tellurium) thin film was used for NOx gas detection at room temperature. By using these sensing materials, micro gas sensors for room temperature operation were prepared and measured the response characteristics for NH3 and NOx.In case of PANi sensor, the structure was inverted staggered FET type having advantage of useful one for Lab-On-a-Chip. The operating principle of the sensor is based on the change in work function of PANi film caused by adsorption of gas molecules in air on the film surface. The change in work function was measured indirectly from that in gate voltage of the FET device. The responses to various gases (NH3, CH4, Methanol and CH3CN) were obtained in gate voltage step mode in R.H. 30%. And in case of Te sensor, the sensing material was thermally evaporated on glass substrate. The thickness and annealing temperature were 500 Å −2000 Å and 100 °C −300 °C, respectively. The Te-based micro gas sensor exhibited high sensitivity to NOx and good selectivity against CO and hydro-carbon gases. And by adding Ti to Te film, the sensor has a good selectivity to CO gas.
Interdiffusion and Reaction of Pd on Atomically Stepped 6H-SiC Surfaces: Progress Toward Thermally Stable High Temperature Gas Sensors
Authors: Stinespring C. D. , Peng C. Y. , Woodworth A. A. , Meehan K. , Murdoch-Kitt M. J. , Anderson C. L. 
Published: April 2011

ABSTRACTHigh temperature Pd-SiC Schottky diode gas sensors are known to thermally degrade due to interdiffusion and reaction at the metal-semiconductor interface. To understand and possibly eliminate this problem, detailed surface studies of thermally induced Pd-SiC surface interactions have been performed. These experiments compare standard 6H-SiC (0001) surfaces typical of those used in device fabrication with periodically stepped surfaces prepared by high temperature hydrogen etching. The Pd films range in thickness from the monolayer level (∼0.4 nm) to actual device dimensions (∼46.5 nm) and are deposited under ultrahigh vacuum conditions at ∼50 °C. These films are characterized in-situ using Auger electron spectroscopy both before and after annealing at 670 °C. The Auger lineshapes provide quantitative information on the chemistry of the reaction products. Ex-situ atomic force microscopy is used to characterize changes in surface morphology.
SiGe Thermoelectric Film for Gas Sensor Micro-Devices
Authors: Shin Woosuck , Tajima Kazuki , Choi Yeongsoo , Izu Noriya , Matsubara Ichiro , Murayama Norimitsu 
Published: April 2011

ABSTRACTA gas sensor micro-device using both thermoelectric film and catalyst film has been developed on the platform of micro-hotplate. Thermoelectric thin film of B-doped SiGe was deposited on the Si3N4/SiO2/Si substrate by helicon sputtering method and thermal annealing was carried out to crystallize the as-deposited amorphous-like film. With increasing the annealing temperature and time, the crystallization of the SiGe thin film progressed, resulting in high carrier mobility and large absolute value of Seebeck coefficient. The hydrogen sensitivity of the micro-thermoelectric gas sensors was investigated.
Lateral Distribution of Electrons Trapped in Nitride Layers
Authors: Lorenzini M. , Rosmeulen M. , Breuil L. , Haspeslagh L. , Van Houdt J. , De Meyer K. 
Published: April 2011

ABSTRACTThe recent advent of nitride-based localized charge-trapping storage has raised much interest in the lateral characterization of the trapped charge distribution, which is fundamental in defining scalability and retention properties. A direct characterization technique based on amplitude-sweep charge-pumping measurements is exploited here to investigate the lateral distribution of trapped electrons along the channel length. Further, the technique is applied to monitor the charge redistribution in time at high temperature.
Long Time Data Retention and A Mechanism in Ferroelectric-Gate Field Effect Transistors with HfO2 Buffer Layer
Authors: Aizawa Koji , Kawashima Yoshihito , Ishiwara Hiroshi 
Published: April 2011

ABSTRACTA mechanism of the long-time data retention in the p-channel MFIS FETs with Pt/SBT/HfO2/Si gate structures was proposed. The MFIS FETs used in this study exhibited the drain current on/off ratio of approximately 6×103 even after 30 days had elapsed at room temperature. From the leakage current characteristics of the MFIS diode, the bulk leakage current density lower than 10-12 A/cm2 was presumed for 30-days data retention. On the other hand, we showed that the decrease of on-state drain current in the retention characteristics was explained by the flat-band voltage shift of approximately -0.3V for 30 days toward negative voltage direction. Therefore, it was also found that the trapped charge density as low as 1011 cm-2 was needed for obtaining the data retention of 30 days.
Excimer (XeCl) Laser Annealing of PbZr0.4Ti0.6O3 Thin Film at Low Temperature for TFT FeRAM Application
Authors: Xianyu W. X. , Cho H. S. , Kwon J. Y. , Yin H.X. , Noguchi T. 
Published: April 2011

ABSTRACTIn this study, we successfully produced PbZr0.4Ti0.6O3 (PZT (40/60)) thin films with high crystallinity and high remnant polarization (Pr) at low process temperatures using pulsed excimer (XeCl) laser irradiation. In our experiments, amorphous PZT films were prepared on Pt/Ti/SiO2/Si substrates by a sol-gel method. A two-step process was used to crystallize the amorphous thin films: the films were annealed at 550°C for 10 min to initiate the nucleation of the PZT perovskite phase, and then annealed with an excimer laser heating at 400°C in a 120 Torr nitrogen gas atmosphere. Laser energy density was varied from 150 to 750 mJ/cm2 per pulse. x-ray diffraction (XRD) patterns show that 150–200 mJ/cm2 range multi-shot excimer laser irradiation drastically improved the crystallinity of the PZT perovskite phase, and FESEM photographs show that the PZT thin film has uniform-sized crystal grains. The ferroelectric properties were found to depend on the laser energy density and shot number. Before the laser annealing, the films show hysteresis loops with low Pr and the loops do not saturate. After laser annealing, the films show highly saturated hysteresis loops, with the Pr increasing from 2.2 μC/cm2 to 23.0 μC/cm2. We also propose a new technology for fabrication of thin film transistor (TFT)-driven FeRAM devices on arbitrary insulator substrate such as on glass.
Development of Nonvolatile Memory using Well-Ordered Ferroelectric Linear Molecules
Authors: Ishida Kenji , Katsumoto Kazunari , Kuwajima Shuichiro , Horiuchi Toshihisa , Yamada Hirofumi , Matsushige Kazumi 
Published: April 2011

ABSTRACTFerroelectric vinylidene fluoride (VDF) molecular films were fabricated by simple vacuum evaporation method, and the ferroelectric properties and its fatigue were investigated. Formation of ferroelectric phase in VDF oligomer with low molecular weight is favored at low substrate temperature around -150°C. The well-ordered VDF oligomer thin films exhibit a lager value of remanent polarization(130mC/m2) than that of Poly(VDF). Fatigues of polarization reversal can be performed over 10∧5 cycles. The VDF oligomer films can be one of candidates for disposable nonvolatile memory with unique features such as flexible, wide areas and low cost processing.
Manipulation of 2D arrays of Si nanocrystals by ultra-low-energy ion beam-synthesis for nonvolatile memories applications
Authors: Bonafos C. , Cherkashin N. , Carrada M. , Coffin H. , Ben Assayag G. , Schamm S. , Dimitrakis P. , Normand P. , Perego M. , Fanciulli M. , Muller T. , Heinig K. H. , Argawal A. , Claverie A. 
Published: April 2011

ABSTRACTIn silicon nanocrystal (nc) based metal-oxide-semiconductor (MOS) memory structures a fine control of the Si nc location in the gate oxide is required for the pinpointing of optimal device architectures. In this work, we show how to manipulate and control the depth-position, size and surface density of two dimensional (2D) arrays of Si ncs embedded in thin (<10 nm) SiO2 layers, fabricated by ultra-low-energy (typically 1 keV) ion implantation and subsequent annealing. Particular emphasis is placed upon the influence of implantation, annealing conditions and oxide thickness on the nanocrystal characteristics (e.g. size, density) and the charge storage properties of associated MOS structures. Structural investigation is performed by using specific characterization methods including Fresnel imaging for the measurement of the injection distance between the substrate and the nc band, as well as spatially resolved Electron Energy Loss Spectroscopy using the spectrum-imaging mode of a Scanning Transmission Electron Microscope to evaluate the size distribution and density of the ncs.
Reliable, Fast and Long Retention Si Nanocrystal Non-Volatile Memories
Authors: Carreras Josep , Garrido B. , Arbiol J. , Morante J. R. 
Published: April 2011

ABSTRACTWe report in this work a Si-nanocrystal (Si-nc) MOS basic cell which shows, at the same time, fast writing times and long charge retention. This has been achieved by optimizing a structure reported previously that exhibited excellent retention characteristics. For the new structure, 15 keV Si ions have been implanted in a 40 nm thick oxide at high doses in order to obtain Si excess ranging from 10 to 20 atomic % at projected range (25nm). An annealing step at 1100 °C has been performed to precipitate the nanocrystals. We show that there is a Si excess compromise (density depth profile of Si-nc) in which write times are improved by at least 3 orders of magnitude (to the submillisecond range) while still maintaining a virtually infinite retention time. Such behavior has been correlated with structural characterization by EFTEM, which reveals a control oxide completely free of Si clusters and thick enough (11 nm) to prevent tunnelling from/to the gate electrode. The Si-ncs are located around the projected range and show a mean size of 2.7 ± 0.2 nm. The tunnel oxide is not completely free of Si-nc or clusters, as observed by EFTEM, but there is a significant reduction in mean size and density when approaching to the p-type substrate. We believe that these small Si-nc or clusters in the tunnel oxide play an important role in improving the performance of the devices. For charging (writing), when a gate bias is applied to the structure, these clusters assist like traps when tunneling to the central region. However, when the Si-nc are already charged, these nanoclusters do not similarly enhance the discharge process because they have larger band-gaps (due to quantum confinement) than the bigger Si-nc in the center of the layer, and therefore act as an insulating material. This simple model, based on the correlation of the most important electrical memory parameters and the structural information, has allowed us to engineer the implantation dose as a technological parameter when a trade-off between write and retention times is required. For our samples, this dose is about of 15% Si excess. Finally, endurance tests have been performed, showing a completely flat and stable programming window after 106 Write/Erase programming pulses.
Improved size dispersion of silicon nanocrystals grown in a batch LPCVD reactor
Authors: Wan Y. M. , van der Jeugd K. , Baron T. , De Salvo B. , Mur P. 
Published: April 2011

ABSTRACTNanocrystal memories are widely invoked as potential solutions to overcome the scaling limitations of conventional FLASH memories beyond the 80nm technology node. In this study, the deposition of uniform silicon nanocrystals has been developed and optimized in a commercially available vertical furnace, an A400 from ASM.It has been shown that low pressure chemical vapor deposition (LPCVD) of nanocrystals is feasible in a batch reactor but with a bad size dispersion of the silicon nanocrystals. To improve the size dispersion of the nanocrystals, a novel 2-step process with silane was introduced. In the conventional 1-step process, the oxide surface is exposed to silane at the same partial pressure and temperature during both nucleation and growth of the silicon nanocrystals. In this novel 2-step process, the surface is first exposed briefly to silane at a higher temperature (580–600°C) and following that, the temperature is lowered to allow selective growth on the existing silicon nuclei over the oxide surface. With such an approach, the nucleation step can be separated from the growth step and consequently the size dispersion can be improved by 50%.
Small “Magnetic” Clusters of Ga and In with As and V
Authors: Pozhar Liudmila A. , Yeates Alan T. , Szmulowicz Frank , Mitchel William C. 
Published: April 2011

ABSTRACTSeveral small clusters of Ga and In with As and V atoms are pre-designed to study effects of spatial constraints on electronic and magnetic properties of such clusters by means of the Hartree-Fock (HF) method. The obtained electronic energy level structures (ELSs), optical transition energies (OTEs) and spin densities of these clusters are compared to those specific to the corresponding clusters nucleated without spatial constraints. The pre-designed indium-based clusters demonstrate the enhanced spin densities as compared to those of the gallium-based clusters with equal numbers of V atoms, and thus can be of interest for applications in spintronic and magneto-optic memory materials development.
All-organic single-transistor permanent memory device
Authors: Schroeder Raoul , Majewski Leszek A. , Voigt Monika , Grell Martin 
Published: April 2011

ABSTRACTWe present an all-organic permanent memory transistor using an amorphous spin-cast gate insulator. This gate insulator exhibits a remanent polarisation in its amorphous state, a unique property, which is best described as “ferroelectric-like”. The memory transistor thus built perform extremely well, even when compared to inorganic ferroelectric memory transistors; the memory “on” to memory “off” current ratio is close to 3×10-a4, while time-dependent studies show retention times of 14 hours and more.
Chemical Vapor Deposition of Germanium Nanocrystals on Hafnium Oxide for Non-Volatile Memory Applications
Authors: Wang Ying Qian , Chen Jing Hao , Yoo Won Jong , Yeo Yee-Chia 
Published: April 2011

ABSTRACTIn this paper, we investigate the chemical vapor deposition (CVD) of Ge nanocrystals (NCs) directly on hafnium oxide HfO2 dielectric for non-volatile memory applications. Germane GeH4 was used as a precursor. Atomic force microscopy (AFM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) were used to characterize the Ge NCs. The dependence of the Ge NC size and density on the deposition temperature, deposition time, and flow rate was explored. A high Ge NC density of 1011 cm-2 was obtained at a deposition temperature of 600°C, with a mean diameter of about 16 nm. MOS capacitors with CVD Ge NCs embedded in the HfO2 gate dielectric were fabricated. Hysteresis of capacitance-voltage (C-V) characteristics of capacitors with Ge NCs was observed, demonstrating memory effect.
Effect of Ta2O5 on Dielectric Properties of Forsterite Ceramics
Authors: Kim Dong-Young , Lee Hong-Yeol , Jun Dong-Suk , Lee Sang-Seog 
Published: April 2011

ABSTRACTFor the millimeter-wave dielectrics, forsterite-based ceramics were produced. Stoichiometric forsterite ceramics (Mg2SiO4) shows porous microstructure and very low Q*f values, which is not suitable for dielectrics in the microwave and millimeter-wave bands. The small addition (0.025 mol%) of Ta2O5 instead of SiO2 enhanced the sinterability of forsterite ceramics. The sintering temperature was reduced more than 150°C by the addition of Ta2O5. The density was greatly increased by Ta2O5 addition. The dielectric constant and Q*f of 0.025 mol% Ta2O5 modified forsterite sintered at 1500°C was 7.3 and 150, 000, respectively in microwave band (8–11GHz). The dielectric constant and Q*f of the same sample measured at 55GHz was 6.7 and 179, 000, respectively. Further addition of Ta2O5 decreases the sintering temperature.
Ferrite Properties and Technology Issues for Improved Microwave Systems
Authors: Dionne Gerald F. , Oates Daniel E. 
Published: April 2011

ABSTRACTMicrowave device engineers continually seek materials advances to improve performance of magnetic components at reduced size and cost. Wherever possible, microstrip or stripline device configurations are adopted in preference to bulky waveguide structures. In radar and communications applications, the nonreciprocal propagation properties of ferrites are essential for realizing phase shifters, circulators, isolators, and power limiters. The introduction of superconductor circuits has led to the development of very low-loss phase shifters and circulators. Recent demonstrations of tuning reciprocal rf permeability by varying the state of magnetization at very low magnetic fields has led to the development of high-speed, high-Q tunable filters. In this paper, design issues of four classes of microwave device are reviewed from the standpoint of their ferrite material requirements: (1) low-loss microstrip phase shifters (2) microstrip tunable resonators, (3) self-biased microstrip circulators with normal or in-plane uniaxial anisotropy, and (4) high-power quasi-optical circulators.
A High K Nanocomposite for High Density Chip-to-Package Interconnections
Authors: Kim Taeyun , Nath Jayesh , Wilson John , Mick Stephen , Franzon Paul D. , Steer Michael B. , Kingon Angus I. 
Published: April 2011

ABSTRACTAC-coupled interconnects (ACCI) is a very exciting technology for achieving high-density chip-to-package interconnects while simultaneously providing a simple, mechanically robust interface. The technology combines the stress-relieving ‘underfill’ layer with the dielectric medium for capacitive coupling. For good AC coupling, it is desirable for the underfill material to have a permittivity around 20 at operating frequencies. However, there is a lack of microwave frequency data for high permittivity ceramic-polymer composite systems in the literature. This paper describes the development and microwave frequency characterization of high K nanocomposite underfill. For composite thick film preparation, 200 nm BaTiO3 nano-sized powder and photosensitive epoxy were used. The thermal behavior of composites was evaluated by DSC (differential scanning calorimetry). Dielectric properties were evaluated as a function of ceramic loading and curing temperature. The microwave dielectric properties were measured from 45 MHz up to 26.5 GHz to extract the capacitance and quality factor of the capacitor over the frequencies of interest using floating plate capacitors and T-resonator CPW structures. The permittivity was found to be ∼ 18 up to 14 GHz and the total Q factor of the capacitors was found to be 2 at 26.5 GHz for BaTiO3 (30 vol%)-epoxy composite. Dielectric loss was found to be 0.3 at 3 GHz, which would satisfactorily allow signaling well into the muti-gigabits range. The high K nanocomposite shows higher permittivity compared to materials currently used (air, K=1 or SiO2, K∼3.9) in capacitively coupled interconnects for chip-to-package communications.