bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thickness Dependent Tetragonal Relaxation of Iron in Epitaxial Fe/Pd Multilayer Films
Authors: Steffl T. , Rellinghaus B. , Mühlbauer H. , Müller CH. , Herper H. , Dumpich G. 
Published: April 2011

ABSTRACTWe have prepared (Fe(001)/Pd(001)) multilayers onto Pd-buffered sapphire substrates. Structural investigations utilizing HRTEM, RHEED and XRD show that the films grow epitaxially for up to 32 bilayers. Whereas the Fe lattice is found to assume the lateral (in-plane) lattice spacing of the underlying Pd layers, the out-of-plane lattice parameter along the [001] growth direction of the film is successively reduced with increasing Fe layer thickness. This outof-plane lattice relaxation even survives a subsequent growth of Pd onto the Fe. Thus, by varying the Fe layer thickness we have control of the atomic volume of Fe. Magnetization measurements reveal that the magnetic moment of Fe is as high as 2.7 µB per atom when the atomic volume is larger than Vat(Fe) ≥ 11.7 Å3 and is reduced to 2.2 µB per atom for Vat(Fe) ≤ 11.1 Å3.
Insulator/GaN Heterostructures of Low Interfacial Density of States
Authors: Hong M. , Ng H. M. , Kwo J. , Kortan A. R. , Baillargeon J. N. , Anselm K. A. , Mannaerts J. P. , Cho A. Y. , Lee C. M. , Chyi J. I. , Lay T. S. , Ren F. , Abernathy C. R. , Pearton S. J. 
Published: April 2011

ABSTRACTA review is given on insulators (oxides and nitrides) which have been deposited on GaN to form metal-insulator (oxides and nitrides)-semiconductor (MOS or MIS) diodes with a low interfacial density of states (Dit). These insulators include AlN, SiO2, Si3N4, SiO2/Ga2O3, and Ga2O3(Gd2O3). Techniques for depositing these insulators and methods for cleaning GaN surfaces prior to the insulator deposition are discussed. Recent progress on GaN MOSFET's (with SiO2/Ga2O3, and Ga2O3(Gd2O3) as gate dielectrics) and MISFET's (with AlN as a gate dielectric) is also reviewed. When exposed to room air, GaN surface is not as robust as previously thought. Therefore, preparation of a clean GaN surface for deposition of oxides and nitrides is necessary to achieve a low Dit. By heating GaN samples in UHV to clean the surfaces followed by deposition of Ga2O3(Gd2O3) and SiO2, we have achieved a low Ditwith negligible hysteretic loops in the capacitance-voltage curves
Present Status of III-Nitride Based Photodetectors
Authors: Monroy Eva , Calle Fernando , Pau José Luis , Muñoz Elías , Omnès Franck , Beaumont Bernard , Gibart Pierre 
Published: April 2011

ABSTRACTThis paper describes the characteristics of a variety of AlGaN-based photodetectors (photoconductors, metal-semiconductor-metal photodiodes, Schottky photodiodes and p-i-n photodiodes), grown on sapphire by metalorganic vapor phase epitaxy. The features that determine their performance are analyzed. Results using other substrates (epitaxial lateral overgrown GaN, Si) are also presented.
Effect of Interface Manipulation for MBE Growth of AlN on 6H-SiC
Authors: Naniwae Koichi , Hartman Jeff , Petrich Chris , Davis Robert F. , Nemanich Robert J. 
Published: April 2011

ABSTRACTAlN layers were grown on 6H-SiC(0001) by molecular beam epitaxy using ammonia as the nitrogen source. Clean (√3×√3)R30° SiC surfaces was prepared by in-situ annealing alone and also by in situ annealing consisted of followed by Si deposition and subsequent annealing. The surface morphology of the AlN films observed by AFM was significantly changed by the nucleation procedure. When the AlN growth was initiated with Al flux exposure on a SiC surface prepared by thermal annealing, the surface roughness of the AlN was significantly reduced. Two-dimensional growth of AlN was observed with reflection high-energy electron diffraction from the very beginning. Atomically flat AlN surfaces with a RMS-roughness of ∼0.3 nm were obtained. On the other hand, when film growth was initiated with an ammonia flux exposure on a Si rich SiC surface, a high density of bumps was observed. The bumps seemed to originate from SiNx formation at the heteroepitaxial interface. It was found that control of the Si composition and the V/III ratio at the growth interface is crucial for the AlN film quality.
Arsenic Incorporation in Gallium Nitride grown by Metalorganic Chemical Vapor Deposition using Dimethylhydrazine and Tertiarybutylarsenic
Authors: Kellermann S. , Yu K. M. , Haller E. E. , Bourret-Courchesne E. D. 
Published: April 2011

ABSTRACTMOCVD growth of As-doped GaN using dimethylhydrazine, triethylgallium and tertiarybutylarsenic has been investigated. A maximum doping concentration of 4.0 × 1019cm−3 at growth temperatures between 600°C and 800°C was obtained. At 1000°C the As doping level dropped below the SIMS detection limit of ∼1.0 × 1017cm−3. The As incorporation depended only weakly on variations of the V/III molar flow ratio between 11 and 61. Raising the As/V molar flow ratio from 0.01 to 0.06 increased the As concentration which then decreased by further increase to 0.11. Different morphologies of the layers were found depending on the growth conditions. A surfactant-like behavior of As was observed leading to smooth GaN films grown on top of the As-doped GaN layer. Two characteristic luminescence peaks at 3.31 eV and 3.425 eV were found for samples doped with As below 900°C. These spectral features are believed to originate at extended lateral defects - presumably stacking faults.
p-GaAs Base Regrowth for GaN HBTs and BJTs
Authors: Dang G. , Zhang A.P. , Cao X.A. , Ren F. , Pearton S.J. , Cho H. , Hobson W.S. , Lopata J. , van Hove J.M. , Klaassen J.J. , Polley C.J. , Wowchack A.M. , Chow P.P. , King D.J. 
Published: April 2011

ABSTRACTLow resistance ohmic contacts are difficult to form to p-type GaN and AlGaN due to the unavailability of growth methods for highly p-doped GaN and AlGaN. A p-type carbon-doped GaAs regrowth on p-GaN prior to ohmic metallization has been shown in previous work to improve contact resistance to p-GaN [13]. Applying the regrowth method to the p-base regions of npn structured bipolar transistors, AlGaN/GaN heterojunction bipolar transistors and GaN bipolar junction transistors have been demonstrated. GaN/AlGaN epilayers were grown with a molecular beam epitaxy system. Highly carbon-doped p-GaAs (1020 cm−3) was regrown on the devices (∼500 Å) in the base contact region by metal organic chemical vapor deposition after emitter mesa etching. Emitter and base mesa structures were formed by Inductively Coupled Plasma etching under low damage conditions with a Cl2/Ar chemistry. SiO2 was used for emitter sidewall formation to reduce leakage current to the emitter, as well as for a mask for GaAs base regrowth. Very high current densities were obtained for common base operation in both device types. The devices were operable at 250 °C.
Stable Ti/TaSi2/Pt Ohmic Contacts on N-Type 6H-SiC Epilayer at 600°C in Air
Authors: Okojie Robert S. , Spry David , Krotine Jeff , Salupo Carl , Wheeler Donald R. 
Published: April 2011

ABSTRACTWe report preliminary electrical and diffusion barrier characteristics of Ti (100nm)/TaSi2 (200nm)/Pt (300nm) thermally stable ohmic contact metallization on n-type 6H-SiC epilayers. These contacts exhibited linear ohmic characteristics with contact resistance in the range of (0.3×10−4−8×10−4) Δcm2 on n-type epilayer doped between 0.6 to 2×1019cm−3. The I-V characteristics and contact resistance remained stable after heat treatments at 500°C and 600°C in air for over 600 hours and 150 hours, respectively. Auger Electron Spectroscopy (AES) was used to analyze the metal and semiconductor interfaces to understand the prevailing reactions. The thermal stability of the ohmic contact between 500°C and 600°C in air is believed to be due to the formation of silicides and carbides of titanium after being annealed at 600°C in H2 (5%)/N2 forming gas for 30 minutes. The oxidation of silicon species that migrated after TaSi2 decomposition is proposed as the diffusion barrier mechanism.
Influence of LaNiO3 as an Electrode on the Properties of Ferroelectric Oxides
Authors: Kalare R. , Vedawyas M. , Kumar A. 
Published: April 2011

AbstractAn electrode plays an important role in realising a ferroelectric thin film as a potential memory device. We have investigated LaNiO3 (LNO) as a potential electrode material and evaluated the ferroelectric properties of oxide materials like strontium bismuth tantalate (SBT) and barium titanate(BT). We have successfully deposited epitaxial films of LNO on Pt coated Si(100) and LaAlO3 (LAO) substrates using the pulsed excimer laser deposition technique. We are able to grow high quality SBT and BT films on top of this LNO layer. The X-ray diffraction revealed the epitaxy of the LNO, SBT and BT films. The ferroelectric properties of SBTand BT were investigated using the RT66A ferroelectric tester.
Growth, Characterization and Electrical Properties of PZT thin Film Heterostructures on Silicon by Pulsed Laser Deposition
Authors: Chattopadhyay Soma , Kvit Alex , Sreenivasank V. , Sharma A.K. , Lee C. B. , Narayan J. 
Published: April 2011

AbstractEpitaxial thin films of PbZr0.52Ti0.48O3 (PZT) have been synthesized successfully on SrRuO3/SrTiO3/MgO/TiN/Si heterostructures by pulsed laser deposition. The films were single phase and had (001) orientation. The deposition parameters were varied to obtain the best epitaxial layer for each of the compounds. Transmission electron microscopy indicated good epitaxy for the entire heterostructure and sharp interfaces between the epilayers. Dielectric and P-E hysteresis loop measurements were carried out with evaporated Ag electrodes. The dielectric constant for the films was found to be between 400-450. The value of saturation polarization Ps, was between 55-60 νC/cm2 and the coercive field Ec varied from 60-70 kV/cm. Integration of PZT films with silicon will be useful for future memory and micromechanical devices.
Light Scattering from Pulsed Laser Deposited BaBi4Ti4O15 Thin Films
Authors: Soni R.K. , Dixit Anju , Katiyar R. S. , Pignolet A. , Satyalakshmi K.M. , Hesse D. 
Published: April 2011

AbstractLight scattering investigations are carried out on BaBi4Ti4O15 (BBiT) which is a member of the Bi-layer structure ferroelectric oxide with n = 4. The BBiT thin films, thickness ∼ 300 nm, were grown on epitaxial conducting LaNiO3 electrodes on epitaxial buffer layers on (100) silicon by pulsed laser deposition. Micro-Raman measurements performed on these films reveal a sharp low-frequency mode at 51 cm−1 along with broad highfrequeficy modes corresponding to other lattice vibrations including TiO6 octahedra. No temperature dependence of the low frequency mode is seen while a weak dependence of the broad high frequency vibrations are observed in the mixed oriented regions. Raman polarization carried out at room temperature indicates that the prominent modes have Alg and Eg symmetries in the BaBi4Ti4O15 thin films.
Lattice Defects in Epitaxial Ba2Bi4Ti5O18 Thin Films Grown by Pulsed Laser Deposition Onto LaNiO3 Bottom Electrodes
Authors: Zakharov N.D. , James A.R. , Pignolet A. , Senz S. , Hesse D. 
Published: April 2011

AbstractEpitaxial, ferroelectric Ba2Bi4Ti5O18 films grown on LaNiO3/CeO2/ZrO2:Y2O3 epitaxial layers on Si(100) are investigated by cross-section high-resolution transmission electron microscopy (HRTEM). The films are perfectly oriented and consist of well-developed grains of rectangular shape. The grain boundaries are strained and contain many defects, especially a new type of defect, which can be described as a staircase formed by repeated lattice shifts of Δ ∼ c/12 ∼ 4.2 Å in the [001] direction. This repeated shift results in seemingly bent ribbons of stacked Bi2O2 planes, involving, however, individual Bi2O2 planes which remain strongly parallel to the (001) plane. These defects contain an excess of bismuth. Other defects found in the grain interior include mistakes in the stacking sequence originating from the presence of single, well-oriented, non-stoichionietric layers intergrown with the stoichiometric Ba2Bi4Ti5O18 film matrix.
Optimizing Fabrication of Buried Oxide Channel Field Effect Transistors
Authors: Schrott A.G. , Misewich J.A. , Copel M. , Abraham D.W. , Neumayer D.A. 
Published: April 2011

AbstractIn this paper we describe improved methods of fabrication for an oxide channel field effect transistor (OxFET) similar in architecture to a conventional FET. We demonstrate that a substrate treatment consisting of a low power oxygen ashing followed by annealing yields a strontium (A-site) terminated surface in single-crystal strontium titanate (STO). This surface termination of the substrate results in pulsed laser deposited cuprate-channel films of improved quality.
Properties of a Novel Amorphous Transparent Conductive Oxide, InGaO3(ZnO)m
Authors: Orita M. , Ohta H. , Hirano M. , Hosono H. , Morita K. , Tanji H. , Kawazoe H. 
Published: April 2011

AbstractNovel amorphous transparent conductive oxides, InGaO3(ZnO)m, where m is an integer less than four, was developed. Optical transmittance in the visible region exceeded over 80 % and the electric conductivity at 300 K was as large as 400 S/cm. Both Seebeck and Hall coefficients exhibited negative values, indicating the conduction was n-type. It was suggested that 4s orbital of Zn2+ played a significant role for the formation of the extended state responsible for the conduction, while In3+ acted as a modifier for the stabilization of amorphous state.
Preparation of PZT-YBCO Heterostructure on YSZ Coated Si by KrF Laser Ablation
Authors: Ebihara Kenji , Mitsugi Fumiaki , Ikegam Tomoaki , Narayan Jagdish 
Published: April 2011

AbstractKrF excimer laser ablation technique is used to fabricate the ferroelectric Pb(ZrxTi1−xO3)(PZT) capacitor on Si(100) substrate. The superconducting YBa2Cu3O71−x(YBCO) and the colossal magnetoresistive La0.8sr0.2MnO3(LSMO) thin films are used as bottom electrodes for the ferroelectric capacitive structure. The YBCO and LSMO films were studied to understand the interface problems with perovskite oxide films. The fabricated PZT/YBCO/YSZ/Si capacitor shows the ferrolectric properties of the remanent polarization of 20pC/cm2 and the coercive field of 40 kV/cm. Post-thermal annealing improves the ferroelctric properties and the results are comparable with that of the PZT/YBCO/MgO(100) structure. The leakage current of the PZT capacitor is discussed.
Single Quantum Well Heterostructures of MgZnO/ZnO/MgZnO on C-Plane Sapphire
Authors: Choopun S. , Chalk D. M. , Yang W. , Vispute R. D. , Ogale S. B. , Sharma R. P. , Venkatesan T. 
Published: April 2011

AbstractThe single quantum well heterostructures of MgZnO/ZnO/MgZnO were grown on c-plane sapphire substrate by pulsed laser deposition. The well width was varied from 10 nm to 40 nm by controlling the deposition rate via number of laser pulsed on ZnO target. Using photoluminescence spectroscopy, we have observed a blue shift with respect to a thick ZnO reference sample when the well width was decreased. These results were fitted with calculations based on the simple square well model using the appropriate electron and holes effective masses. The quantized-energy and band offset as a function of well width, growth conditions, interface roughness, and possible quantum size effects on the quantum wells are discussed.
Properties of Amorphous and Crystalline Ta2O5 Thin Films Prepared by Metalorganic Solution Deposition Technique for Integrated Electronic Devices
Authors: Joshi P.C. , Cole M.W. 
Published: April 2011

AbstractWe report on the properties of Ta2O5 thin films prepared by the metalorganic solution deposition (MOSD) technique on Pt-coated Si, n+-Si, and poly-Si substrates. The effects of postdeposition annealing temperature on the structural, electrical, and optical properties were analyzed. The electrical measurements were conducted on MIM and MIS capacitors. The dielectric constant of amorphous Ta2O5 thin films was in the range 29.2-29.5 up to 600°C, while crystalline thin films, annealed in the temperature range 650–750°C, exhibited enhanced dielectric constant in the range 45.6–51.7. The dielectric loss factor did not show any appreciable dependence on the annealing temperature and was in the range 0.006–0.009. The films exhibited high resistivities of the order of 1012–1015 Δ-cm at an applied electric field of 1 MV/cm in the annealing temperature range of 500-750 °C. The temperature coefficient of capacitance was in the range 52-114 ppm/°C for films annealed in the temperature range 500-750°C. The bias stability of capacitance, measured at an applied electric field of 1 MV/cm, was better than 1.41 % for Ta2O5 films annealed up to 750°C.
Laser Guided Direct Writing
Authors: Renn Michael J. 
Published: April 2011

ABSTRACTLaser-induced optical forces are used to guide and deposit 100 nm - 10 µm diameter particles onto solid surfaces in a process called laser-guided direct-writing. Nearly any particulate material, including both biological and electronic materials, can be manipulated and deposited with micrometer accuracy. Potential applications include three-dimensional cell patterning for tissue engineering, hybrid biological and electronic device construction, and biochip array fabrication
Photo-Induced Large Area Growth of Dielectrics With Excimer Lamps
Authors: Boyd Ian W. , Zhang Jun-Ying 
Published: April 2011

ABSTRACTIn this paper, UV-induced large area growth of high dielectric constant (Ta2O5, TiO2and PZT) and low dielectric constant (polyimide and porous silica) thin films by photo-CVD and sol-gel processing using excimer lamps, as well as the effect of low temperature UV annealing, are discussed. Ellipsometry, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), UV spectrophotometry, atomic force microscope (AFM), capacitance-voltage (C-V) and current-voltage (I-V) measurements have been employed to characterize oxide films grown and indicate them to be high quality layers. Leakage current densities as low as 9.0×10−8 A·cm−2and 1.95×10−7 A·cm−2at 0.5 MV/cm have been obtained for the as-grown Ta2O5 films formed by photo-induced sol-gel processing and photo-CVD, respectively – several orders of magnitude lower than for any other as-grown films prepared by any other technique. A subsequent low temperature (400°C) UV annealing step improves these to 2.0×10−9A·cm−2and 6.4×10−9A·cm−2, respectively. These values are essentially identical to those only previously formed for films annealed at temperatures between 600 and 1000°C. PZT thin films have also been deposited at low temperatures by photo-assisted decomposition of a PZT metal-organic sol-gel polymer using the 172 nm excimer lamp. Very low leakage current densities (10−7A·cm2) can be achieved, which compared with layers grown by conventional thermal processing. Photo-induced deposition of low dielectric constant organic polymers for interlayer dielectrics has highlighted a significant role of photo effects on the curing of polyamic acid films. I-V measurements showed the leakage current density of the irradiated polymer films was over an order of magnitude smaller than has been obtained in the films prepared by thermal processing. Compared with conventional furnace processing, the photo-induced curing of the polyimide provided both reduced processing time and temperature. A new technique of low temperature photo-induced sol-gel process for the growth of low dielectric constant porous silicon dioxide thin films from TEOS sol-gel solutions with a 172 nm excimer lamp has also been successfully demonstrated. The dielectric constant values as low as 1.7 can be achieved at room temperature. The applications investigated so far clearly demonstrate that low cost high power excimer lamp systems can provide an interesting alternative to conventional UV lamps and excimer lasers for industrial large-scale low temperature materials processing
Charged Molten Metal Droplet Deposition as a Direct Write Technology
Authors: Orme M. , Courter J. , Liu Q. , Zhu J. , Smith R. 
Published: April 2011

ABSTRACTThe formation of highly uniform charged molten metal droplets from capillary stream breakup has recently attracted significant industrial and academic interest for applications requiring high-speed and high-precision deposition of molten metal droplets such as direct write technologies. Exploitation of the high droplet production rates intrinsic to the phenomenon of capillary stream break-up and the unparalleled uniformity of droplet sizes and speeds attained with proper applied forcing to the capillary stream make many new applications related to the manufacture of electronic packages, circuit board printing and rapid prototyping of structural components feasible. Recent research results have increased the stream stability with novel acoustic excitation methods and enable ultra-precise charged droplet deflection. Unlike other modes of droplet generation such as Drop-on-Demand, droplets can be generated at rates typically on the order of 10,000 to 20,000 droplets per second (depending on droplet diameter and stream speed) and can be electrostatically charged and deflected onto a substrate with a measured accuracy of ±12.5 µm. Droplets are charged on a drop-to-drop basis, enabling the direct writing of fine details at high speed. New results are presented in which fine detailed patterns are “printed” with individual molten metal solder balls, and issues relevant to the attainment of high quality printed artifacts are investigated.
Pattern Writing by Implantation in a Large-Scale PSII System With Planar Inductively Coupled Plasma Source
Authors: Wu Lingling , Gao Hongjun , Manos Dennis M. 
Published: April 2011

ABSTRACTA large-scale plasma source immersion ion implantation (PSII) system with planar coil RFI plasma source has been used to study an inkless, deposition-free, mask-based surface conversion patterning as an alternative to direct writing techniques on large-area substrates by implantation. The apparatus has a 0.61 m ID and 0.51 m tall chamber, with a base pressure in the 10−8 Torr range, making it one of the largest PSII presently available. The system uses a 0.43 m ID planar rf antenna to produce dense plasma capable of large-area, uniform materials treatment. Metallic and semiconductor samples have been implanted through masks to produce small geometric patterns of interest for device manufacturing. Si gratings were also implanted to study application to smaller features. Samples are characterized by AES, TEM and variable-angle spectroscopic ellipsometry. Composition depth profiles obtained by AES and VASE are compared. Measured lateral and depth profiles are compared to the mask features to assess lateral diffusion, pattern transfer fidelity, and wall-effects. The paper also presents the results of MAGIC calculations of the flux and angle of ion trajectories through the boundary layer predicting the magnitude of flux as a function of 3-D location on objects in the expanding sheath
Lateral Dye Distribution With Ink-Jet Dye Doping of Polymer Organic Light Emitting Diodes
Authors: Madigan Conor F. , Hebner Thomas R. , Sturm J. C. , Register Richard A. , Troian Sandra 
Published: April 2011

AbstractIn this work we investigate the lateral dye distribution resulting from the dye doping of a thin polymer film by ink-jet printing (IJP) for the integration of color organic light emitting diodes (OLED's). The dye is found to segregate into distinct outer rings following rapid droplet evaporation, while slower evaporation rates are found to significantly reduce (or eliminate) this effect. The dye segregation phenomena are found to depend critically on the mechanisms of droplet evaporation. Good dye uniformity was obtained using a low vapor pressure solvent, and integrated, 250 micron red, green, and blue polymer organic light emitting diodes (OLED's) were fabricated with this technique. These devices had good color uniformity over most of the device area and similar electrical properties to comparable spin-coated devices without IJP.