bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrathin Slices of Ferroelectric Domain-Patterned Lithium Niobate by Crystal Ion Slicing
Authors: Scrymgeour David A. , Gopalan Venkat , Haynes Tony E. , Levy Miguel 
Published: April 2011

ABSTRACTWe report the successful fabrication of 6 µm thick slices from a ferroelectric domain micro-engineered LiNbO3 wafer device using the crystal ion slicing technique. The device was created by micropatterning ferroelectric domains in a bulk 0.3 mm thick wafer of z-cut LiNbO3, followed by ion-implanting with 3.8 MeV He+ ions to a fluence 5 × 10+16 ions/cm2 to create a damage layer at a well defined depth from the surface. Etching away this damaged layer in dilute hydrofluoric acid results in a liftoff of the top slice in which the ferroelectric domain patterns are left intact. The influence of annealing conditions on liftoff time and depth of etch lines was studied. Helium-Neon laser light was successfully coupled into the device. Due to unintentional breakage of the polished input and output faces, the electro-optic scanning performance has not been characterized so far.
Very Low Temperature E-gun Evaporated Gate Oxide of TFTs on Plastic Substrates
Authors: Kim Cheon-Hong , Jung Sang-Hoon , Han Min-Koo 
Published: April 2011

AbstractA high-quality silicon dioxide (SiO2) suitable for a gate oxide on plastic substrates is successfully deposited by e-gun evaporation at room temperature. The e-gun evaporated oxide film is free from troublesome hydrogen atoms and high-energy ion damage, which ensures good electrical characteristics. N2O/N2 plasma post-treatment was effective to reduce the flat band voltage and leakage current of the evaporated oxides due to the passivation of high-energy nitrogen and oxygen radicals. In the SiO2 film treated by N2O/N2 plasma for 1 minute, the flat band voltage has been reduced from −2.5V to about −0.5V and the leakage current has been decreased by more than one order. Our experimental results show that very low temperature SiO2 film suitable for a gate insulator of TFTs on the plastic substrates has been successfully obtained by the e-gun evaporation and N2O/N2 plasma post-treatment.
Fabrication and Characterization of Poly-Si Schottky-Barrier Thin-Film Transistors
Authors: Lin Horng-Chih , Huang Tiao-Yuan , Yeh Kuan-Lin , Huang Rou-Gu , Wang Meng-Fan 
Published: April 2011

AbstractPoly-Si Schottky-barrier thin-film transistors (SB-TFTs) were fabricated and characterized. In this study, SB-TFTs were first fabricated by using a conventional sidewall spacer to isolate the gate and S/D regions during salicidation. However, it was found that these SB-TFTs depict very poor on/off current ratio (<103) as well as severe GIDL (gate-induced drain leakage)-like leakage current. To overcome these shortcomings, a novel SB-TFT structure is also fabricated in this study to improve the device performance. The new device consists of a field-induced-drain region (FID), which is an offset drain region controlled by a metal field-plate lying on top of the passivation oxide. The FID region is sandwiched between the silicided drain and the active channel region. Carrier types and the conductivity of the transistor are controlled by the metal field-plate. Since the metal field plate is formed simultaneously with the regular metal patterning, no additional processing steps are required. Our results show that the new device can significantly improve the on/off current ratio to over 106 for both p- and n-channel operations, while effectively eliminating the GIDL-like leakage.
Large Area Mems: Materials Issues and Applications
Authors: Daniel J.H. , Street R.A. , Teepe M. , Ready S.E. , Ho J. , Wang Y. , Rodkin A. , Alimonda A. , Apte R.B. , Goredema A. , Boils-Boissier D.C. , Kazmaier P.M. 
Published: April 2011

AbstractConventional MEMS devices are based on silicon micro-machining and their maximum size is limited by the wafer. In contrast, we are exploring micro-machining for large area applications on substrates such as glass using polymeric materials. Our research is focused on the photopolymer SU-8, and we apply the MEMS fabrication technology to large area image sensors and displays. There are many challenges concerning the materials and processes, since large area compatibility is essential and integration with large area electronics may be required. The adhesion of SU-8 to the underlying layers as well as stress in the SU-8 are important issues and surface treatments have been investigated. Two applications of SU-8 MEMS are discussed to illustrate large area applications:. First, in the fabrication of an X-ray imager, high aspect ratio SU-8 walls form a micro-patterned phosphor screen to increase the image resolution. Second, a similar approach of patterning SU-8 into arrays of micro-cells is applied to an electrophoretic display.
Effect of a-SiC:H Film Composition on the Performance of Large Area Optical Sensors
Authors: Louro P. , Vygranenko Yu. , Fernandes M. , Vieira M. , Schubert M. 
Published: April 2011

AbstractA series of large area single layers and heterojunction cells in the assembly glass/ZnO:Al/p (SixC1-x:H)/i (Si:H)/n (SixC1-x:H)/Al (0<x<1) were produced by PE-CVD at low temperature. Junction properties, carrier transport and photogeneration are investigated from dark and illuminated current-voltage and capacitance-voltage characteristics. For the heterojunction cells Atypical J-V characteristics under different illumination conditions are observed leading to poor fill factors. High serial resistances around 106 Ω are also measured. These experimental results were used as a basis for the numerical simulation of the energy band diagram, and the electrical field distribution of the whole structures. Further comparison with the sensor performance gave satisfactory agreement.Results show that the conduction band offset is the most limiting parameter for the optimal collection of the photogenerated carriers. As the optical gap increases and the conductivity of the doped layers decreases, the transport mechanism changes from a drift to a diffusion-limited process.
Characteristics of Large-Area Plasma Enhanced Chemical Vapor Deposited TEOS Oxide with Various Short-Time Plasma Treatments
Authors: Chang Ting-Kuo , Lin Ching-Wei , Tseng Chang-Ho , Cheng Huang-Chung , Peng Yuan-Ching , Wang Wen-Tung 
Published: April 2011

AbstractIn this work, high quality silicon dioxide (SiO2) films were prepared by large-area plasmaenhanced chemical vapor deposition (LA-PECVD) using tetraethylorthosilicate(TEOS)-oxygen based chemistry. The effects of various short-time plasma treatments on these as-deposited TEOS oxide were also investigated. Different plasma treatments such as O2, N2O, and NH3 were used in our experiments. Electrical characteristics were exploited to examine the effects of plasma treatments. It was shown that after N2O, and NH3 plasma treatments, the electrical strength of oxide was enhanced. Besides, NH3 plasma treatment exhibited the highest enhancement efficiency. O2- plasma treatment, however, showed some harmful effects on the electrical properties of the TEOS oxide. The reliability tests including charge to breakdown (Qbd) and bias temperature stress (BTS) were also analyzed in these samples. Although better pre-stress characteristics were observed in those samples treated by NH3-plasma, samples with N2O plasma treatment showed superior stress endurance. Consequently, N2O plasma treatment seems to be the best candidate for future TFTs under the consideration of long-term reliability.
UV-Optics for Excimer Laser based Crystallization Processes
Authors: Kahlert H.-J. , Simon Frank , Burghardt Berthold 
Published: April 2011

AbstractLaser based crystallization of thin amorphous films on glass substrates have entered into industrial applications since several years. The excimer laser based process provides a low temperature procedure to obtain polycrystalline silicon films on flat panel display substrates to fabricate thin film transistors (TFT's).The key to this application is a uniform illumination of the. Line Beam systems provide up to 365mm long homogeneous exposure fields operated with up to 300 W average power 308nm excimer lasers. The paper covers a technical overview of Line Beam Optics layout, recent developments and results.Further high resolution optics are described and discussed for sequential lateral solidification (SLS) (1,2,3) processes. The SLS application has demonstrated to efficiently produce directionally solidified microstructures or even grain-boundary –free regions on Si-films. Diffraction limited resolution in the range of several micrometers and high optical throughput are important parameters to this application.General considerations are presented to describe technical limits which compromise laser beam related coherence effects, optimum uniform illumination, adequate resolution and depth of focus and optical efficiency for the practical application.
Capacitance-Voltage (C-V) Hysteresis in the Metal-Oxide-Semiconductor Capacitor with Si Nanocrystals Deposited by the Gas Evaporation Technique
Authors: Mishra Puspashree , Nozaki Shinji , Sakura Ryuta , Morisaki Hiroshi , Ono Hiroshi , Uchida Kazuo 
Published: April 2011

AbstractCapacitance-Voltage (C-V) hysteresis was observed in the Metal-Oxide-Semiconductor (MOS) capacitor with silicon nanocrystals. The MOS capacitor was fabricated by thermal oxidation of Si nanocrystals, which were deposited on an ultra-thin thermal oxide grown previously on a p-type Si substrate. The Si nanocrystals were deposited by the gas evaporation technique with a supersonic jet nozzle. The size uniformity and the crystallinity of the Si nanocrystals are found to be better than those fabricated by the conventional gas evaporation technique. The C-V hysteresis in the MOS capacitor is attributed to electron charging and discharging of the nanocrystals by direct tunneling though the ultra-thin oxide between the nanocrystals and the substrate. The flat-band voltage shift observed during the C-V measurement depends on the size and density of the nanocrystals and also on the magnitude of the positive gate bias for charging. The retention characteristic is also discussed.
The Characterization of Initial Growth of Polycrystalline Silicon Germanium Films on Zirconium Oxide
Authors: Kim Dong-Won , Prins Freek , Ko Kil-Soo , Lee C. H. , Kwong Dim-Lee , Banerjee Sanjay 
Published: April 2011

AbstractIn this study, the initial growth characteristics of a SiGe film realized by ultrahigh-vacuum chemical vapor deposition (UHV CVD) using GeH4 and Si2H6 on high-K gate oxide, ZrO2, has been investigated in the temperature range from 475°C to 550°C. The influence of surface reactions on growth characteristics such as the incubation of growth, roughness of the SiGe layer, and the interface reaction of the SiGe film with ZrO2were studied using atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). From our analysis we conclude that ZrO2 reacts with Si and forms zirconium silicide in the temperature range between 500°C and 550°C. The surface roughness of amorphous SiGe layers increase from 0.5nm to 1.5nm by increasing Ge content from 0.1 to 0.3. A further increase of surface roughness is observed from less than 1nm to 5nm as SiGe layer transitions from an amorphous to a poly crystalline layer.
Influence of Mg on Resistivity, Adhesion, Agglomeration of Ag(Mg)/SiO2/Si Multilayers
Authors: Kang Bongjoo , Yang Heejung , Hong Sungjin , Ko Yeonkyu , Jeong Chang-Oh , Lee Jaegab 
Published: April 2011

AbstractThe effect of Mg in Ag(Mg)/SiO2/Si multilayers on adhesion, agglomeration, and resistivity after annealing in vacuum at 200 to 500 have been investigated. The annealing of Ag(Mg)/SiO2/Si multilayers produced surface and interfacial MgO layers, resulting in MgO/Ag(Mg)/MgO/SiO2/Si structure. The presence of surface MgO provided the passivation against air, thus leading to the significantly enhanced resistance to agglomeration. In addition, the resistivity of Ag(Mg) film decreased by lowering Mg content and increasing the annealing temperature as well. Furthermore, Ag adhesion to SiO2 was improved due to the formation of the interfacial MgO layer resulting from the reaction of segregated Mg with SiO2. Also, the negligible solubility of Si in Ag prevented the dissolution of free silicon produced from the reaction, Mg + SiO2 = MgO + Si, which was in contrast with the dissolution of a significant amount of silicon released from the SiO2 substrate in Cu(Mg)/SiO2/Si multilayers after annealing at high temperature, e.g., 400. The dissolved Si in Cu caused the rapid increase in resistivity in Cu(Mg)/SiO2/Si.
Fabrication of MEMS Tonpilz Transducers
Authors: Zhou Q. F. , Wang L.-P. , Gerber G. , Meyer R. , Tol D. Van , Tadigadapa S. , Hughes W. J. , Trolier-McKinstry S. 
Published: April 2011

AbstractTonpilz transducers consist of a heavy tail mass, a piezoelectric spring, and a light head mass. Miniaturized tonpilz transducers are potentially interesting for the 10 to100 MHz frequency range in imaging transducers due to their high efficiency and output capabilities. Piezoelectric thin films can be used as the active element in the construction of miniaturized tonpilz structures. A 4-10 νm film is necessary for the mass-spring-mass system to resonate at these high frequencies. In this work, fabrication and characterization of lead zirconate titanate (PZT) thick films on conductive oxide LaNiO3 (LNO) coated silicon on insulator (SOI) substrates will be reported for this application. First, conductive LNO thin films, approximately 300 nm in thickness, were grown on SOI substrates by a metal-organic decomposition (MOD) method. The room temperature resistivity of the LNO was 6.5×10-4 ωcm. Randomly oriented PZT (52/48) films up to 7 νm thick were then deposited using a sol-gel process on the LNO coated SOI substrates. 20 mol.% excess lead was added to the solutions to compensate for lead volatilization during film heat treatments. PZT films with LNO bottom electrodes showed good dielectric and ferroelectric properties. The dielectric permittivity (at 1 kHz) was over 1000. The remanent polarization of PZT films was larger than 26 νC/cm2. The e31,f coefficient of PZT thick films was larger than –6.5 C/m2 when poled at -75 kV/cm for 15 minutes. A silver layer approximately 40 νm thick was screen- printed onto the PZT film to form the tail mass of the tonpilz structure. Elements were diced and the bulk silicon was removed by dry and wet-etching methods to leave the p-type silicon layer as tonpilz head mass. Fabrication of MEMS tonpilz microstructures will also be presented.
Mechanical Properties of 0.1 Micron Thick Simox Film Measured Using on-Chip Tensile Test System
Authors: Amano J. , Ando T. , Shikida M. , Sato K. , Tsuchiya T. 
Published: April 2011

AbstractWe evaluated the mechanical properties of a very thin single-crystal-silicon film 140 nm thick fabricated from a SIMOX wafer using an on-chip tensile testing method. The silicon specimen oriented in the <110> direction was integrated with a loading mechanism on the same chip, which was fabricated in three etching steps. The strain in the film was measured using a newly developed tensile testing system having a two-field-of-view microscope that allowed us to observe the elongation of the specimen directly. The measured fracture strain was distributed in the range of 2.4-3.2%, which is narrower than the range of 1.3-3.5% for a thicker 5-νm film.
Fabrication by Inclined-Substrate Deposition of Biaxially Textured Buffer Layer for Coated Conductors
Authors: Balachandran U. , Ma B. , Li M. , Koritala R. E. , Fisher B. L. , Erck R. A. , Dorris S. E. 
Published: April 2011

ABSTRACTInclined substrate deposition (ISD) offers the potential for rapid production of high-quality biaxially textured buffer layers suitable for YBCO-coated conductors. We have grown biaxially textured MgO films by ISD at deposition rates of 20–100 Å/sec. Columnar grain structures with a roof-tile-shaped surface were observed in the ISD-MgO films. X-ray pole figure analysis revealed that the (002) planes of the ISD-MgO films are titled at an angle from the substrate normal. A small phi-scan full-width at half maximum (FWHM) of ≈9° was observed on MgO films deposited at an inclination angle of 55°. YBCO films were also grown on ISD-MgO-buffered Hastelloy C276 substrates by pulsed laser deposition. We obtained a critical current density of ≈2 × 105 A/cm2 at 77 K in self-field on 0.5-μm-thick, 0.5-cm-wide, 1-cm-long samples. This work has demonstrated that biaxially textured ISD MgO buffer layers deposited on metal substrates are promising candidates for fabrication of high-quality YBCO-coated conductors.
Single Buffer Layer Technology for YBCO Coated Conductors
Authors: Paranthaman M. Parans , Aytug T. , Zhai H. Y. , Sathyamurthy S. , Christen H. M. , Martin P. M. , Christen D. K. , Erickson R. E. , Thomas C. L. 
Published: April 2011

ABSTRACTIn an effort to develop alternative single buffer layer technology for YBa2Cu3O7-δ (YBCO) coated conductors, we have investigated LaMnO3 (LMO) as a potential buffer layer. High-quality LMO films were grown directly on biaxially textured Ni and Ni-W (3%) substrates using rf magnetron sputtering. YBCO films were then grown on LMO buffers using pulsed laser deposition. Detailed X-ray studies have shown that both YBCO and LMO layers were grown with a single epitaxial orientation. Rutherford backscattering spectroscopy (RBS) analyses have indicated the ratio of La to Mn ratio is 1:1. SEM micrographs indicated that 3000-Å-thick LMO films on biaxially textured Ni (100) substrates were dense, continuous and crack-free. A high Jc of over 1 MA/cm2 at 77 K and self-field was obtained on YBCO films grown on LMO-buffered Ni or Ni-W substrates. We have identified LaMnO3 as a good diffusion barrier layer for Ni and it also provides a good template for growing high current density YBCO films.
Initial Assessment of the Thermoelectric Properties for the Mixed System K2−xRbxBi8Se13
Authors: Ireland John R. , Kyratsi Theodora , Kanatzidis Mercouri G. , Kannewurf C. R. 
Published: April 2011

ABSTRACTIn previous studies we have investigated the thermoelectric properties of undoped and doped compositions of β-K2Bi8Se13. The attempt to substitute Rb for K resulted in a different structure type, but with potentially useful thermal properties. In this paper the results of measuring the thermoelectric properties of small crystalline samples for K2−xRbxBi8Se13 solid solutions are reported for the compositional ranges with 0 ≤ × ≤ 1 and with 1.8 ≤ × ≤ 2. The presence of rubidium provides a significant improvement in the thermopower but has much less of an effect on the electrical conductivity. The combined results are reflected in the power factor behavior as a function of temperature.
Commercial Apparatus for Measuring Thermal Transport Properties from 1.9 to 390 Kelvin
Authors: Dilley N.R. , Black R.C. , Montes L. , Wilson A. , Simmonds M.B. 
Published: April 2011

ABSTRACTWe have developed an instrument which simultaneously measures the thermal conductivity κ, Seebeck coefficient α, and electrical resistivity ρ of a sample, thereby determining the thermoelectric figure of merit Z = α2/(κρ). A Quantum Design Physical Property Measurement System (PPMS) provides the temperature control from 1.9 - 390 K and applied magnetic fields of up to 14 tesla. Two small probes mounted along the sample each contain thin film Cernox chip thermometers as well as electrical contacts to monitor the temperature and voltage drops across the sample. A third probe attached to the end of the sample provides a heater and current source to stimulate the sample both thermally and electrically. The sample's response to cyclic heat pulses is analyzed in real time using DSP techniques. A nonlinear least-squares fit is used, employing a two time-constant model to determine both the thermal conductivity and the Seebeck coefficient for the material. Data acquisition using these ac techniques are expedited since we can sweep both temperature and field during a measurement. Adaptive algorithms continually adjust the thermal and electrical stimuli applied to the sample, optimizing the speed and accuracy of the measurement. We present results from some of the materials measured so far, including thermal conductivity standards and Pb in the superconducting state.
Pressure Effect of Seebeck Coeffcient for Zinc Doped Tin Clathrates
Authors: Chen F. , Stokes K. L. , Nolas G. S. 
Published: April 2011

ABSTRACTWe measured the temperature dependence of electrical resistance (R) and thermopower (S) of Cs8Zn4Sn42 under high pressure up to 1.2 GPa. Both R and ∣S∣ at room temperature increased with pressure. We observed gap widening, irreversible ∣S∣ increasing under high pressure, which were similar to the behaviors of Cs8Sn44. However, the relaxation e.ect of R for Cs8Zn4Sn42 was negligible in contrast with that of Cs8Sn44. We found that the power factor S2σ (σ: electrical conductivity) near room temperature decreased linearly with pressure. The results suggest that the defects in different forms played an important role in transport properties for tin clathrates under high pressure.
High Cooling Power Density of SiGe/Si Superlattice Microcoolers
Authors: Zeng Gehong , Fan Xiaofeng , LaBounty Chris , Bowers John E. , Croke Edward , Christofferson James , Vashaee Daryoosh , Zhang Yan , Shakouri Ali 
Published: April 2011

ABSTRACTFabrication and characterization of SiGe/Si superlattice microcoolers integrated with thin film resistors are described. Superlattice structures were used to enhance the device performance by reducing the thermal conductivity, and by providing selective emission of hot carriers through thermionic emission. Thin film metal resistors were integrated on top of the cooler devices and they were used as heat load for cooling power density measurement. Various device sizes were characterized. Net cooling over 4.1 K and a cooling power density of 598 W/cm2 for 40 × 40 μm2 devices were measured at room temperature.
When Does a Crystal Conduct Heat Like a Glass?
Authors: Sales B. C. , Chakoumakos B. C. , Keppens V. , Jin R. , Mandrus D. , Thompson J. R. 
Published: April 2011

ABSTRACTSemiconducting crystalline materials that are poor conductors of heat are important as thermoelectric materials and for technological applications involving thermal management. In the present article neutron scattering, electrical and thermal transport, heat capacity, magnetic and acoustic measurements are reported on single crystals of three semiconductors with the type I clathrate structure: Ba8Ga16Ge30, Sr8Ga16Ge30 and Eu8Ga16Ge30. Taken together these measurements suggest specific structural features that result in a crystal with the lowest possible thermal conductivity, namely that of a glass with the same chemical composition. Weakly bound atoms that rattle within oversized atomic cages in a crystal result in a low thermal conductivity, but the present data show that both rattling atoms and tunneling states are necessary to produce a true glass-like thermal conductivity.
Structure and Thermoelectric Properties of New Layered Compounds in the Quaternary System Cs-Pb-Bi-Te
Authors: Hsu Kuei-Fang , Chung Duck-Young , Lal Sangeeta , Hogan Tim , Kanatzidis Mercouri G. 
Published: April 2011

ABSTRACTBy introducing of various equivalents of PbTe into the layered framework of CsBi4Te6, the four new compounds CsPbBi3Te6 (1), CsPb2Bi3Te7 (2), CsPb3Bi3Te8 (3) and CsPb4Bi3Te9 (4), were discovered. The compounds adopt layered structures built up of anionic slabs of progressively increasing thickness. The [PbmBi3Te5+m]- (m = 1, 2, 3, 4) slabs in the four structures can be viewed as fragments excised from the PbTe-type structures with 4-, 5-, 6- and 7-monolayers, respectively. As prepared, these materials are off-stoichiometric and n-type conductors. We present preliminary results of the crystal structures and thermoelectric properties of these materials and classify them as members of the new homologous series CsPbmBi3Te5+m (m = 1 to 4).