bluuebunny/crossref_metadata_2025_split huggingface dataset:
Room-temperature Ferromagnetic Zn0.95Co0.05O Diluted Magnetic Semiconducting Thin Films by Pulsed Laser Deposition
Authors: Zhang Yuebin , Liu Qing , Sritharan Thirumany , Gan Chee-Lip , Li Sean 
Published: April 2011

ABSTRACTCo-doped ZnO thin films with room-temperature ferromagnetism have been successfully synthesized on (001) Si substrates at 450 °C by pulsed-laser deposition using a Zn0.95Co0.05O ceramic target. Their microstructural properties are carefully studied using atomic force microscopy, x-ray diffraction and high-resolution transmission electron microscopy. The oxidation state of Co and the ratio of Co/Zn are examined by x-ray photoelectron spectroscopy, and magnetic measurements are performed using SQUID. The results show that a single-phase crystalline Co-doped ZnO film was grown with (002) preferential orientation and some edge dislocations formed during the film growth. The origin of room-temperature ferromagnetism is explored. The presence of nanoclusters of any magnetic phase can be ruled out. The dislocations, coupled with oxygen vacancy, may contribute to the ferromagnetic properties in the much diluted magnetic semiconductor.
Some studies on Molybdenum doped Indium oxide thin films rf sputtered at room temperature
Authors: Elangovan E. , Barquinha P , Pimental A , Viana A. S. , Martins R , Fortunato E 
Published: April 2011

ABSTRACTThin films of molybdenum doped indium oxide (IMO) were rf sputtered onto glass substrates at room temperature. The films were studied as a function of oxygen volume percentage (OVP) ranging 1.4 - 10.0 % in the sputtering chamber. The thickness of the films found varying between 180 and 260 nm. The X-ray diffraction pattern showed the films are polycrystalline with the peaks corresponding to (222) and (400) planes and one among them showing as a preferential orientation. It is observed that the preferred orientation changes from (222) plane to (400) as the OVP increases from 1.4 to 10.0 %. The transmittance spectra were found to be in the range of 77 to 89 %. The optical band gap calculated from the absorption coefficient of transmittance spectra was around 3.9 eV. The negative sign of Hall coefficient confirmed the films were n-type conducting. The bulk resistivity increased from 2.26 × 10−3 to 4.08 × 10−1 Ω−cm for the increase in OVP from 1.4 to 4.1 %, and thereafter increased dramatically so as the Hall coefficients were not detectable. From the AFM morphologies it is evaluated that the RMS roughness of the films ranges from 0.9 to 3.2 nm.
Surface Modifications of CMR Manganite Thin Films Using Atomic Force Microscope
Authors: Schaefer David Matthew , Sneider Matthew , Bolling Cameron , Sunderland John , Davidson Anthony L. , Kolagani Rajeswari M. , Bradley Tyler , Ludka Bonnie , Hall Kyle 
Published: April 2011

ABSTRACTReproducible nanoscale surface lithography have been produced on La00.66Ba0.33MnO3 thin films using Atomic Force Microscopy. Using an anodic oxidation technique, structures were produced using both positive tip bias voltages as well as negative tip voltages. The electric field produced by applying a positive tip bias acts to reduce the region near the surface, whereas negative tip bias causes an oxidation reaction. Using a positive tip bias, stable structures were consistently achieved which demonstrated a linear dependence of height and width on tip voltage and writing speed. Heights ranged from 5 – 50 nm and widths from 400 – 2000 nm. Negative bias voltages produced a rapid oxidation of the surface, resulting in uncontrollable writing. After etching with a 50% HCL solution it was found that controlled writing was possible with negative bias voltages.
Electrical Characteristics of BaxSr1-xTiO3(BST) Capacitors Implemented with Ti-Al Electrodes
Authors: Kalkur Thottam S , Whitescarver Jeff , Cramer Nick 
Published: April 2011

AbstractTi-Al was used as the electrode for RF magnetron sputtered BST film at a substrate temperature of 450°C for decoupling capacitor applications. X-ray diffraction analysis shows that the deposited film BST film is amorphous. Electrical characterizations of the devices performed by capacitance versus voltage measurements show a dielectric constant of about 55. With increase in annealing temperature above 450°C, the capacitance was found to decrease significantly.
Thermoelectric Properties of Nano-structure Controlled Sm2−xCexCuO4 Thin Films
Authors: Ichino Yusuke , Yamazaki Koji , Yoshikawa Tomoki , Yoshida Yutaka , Takai Yoshiaki 
Published: April 2011

ABSTRACTSm2−xCexCuO4 (SCCO) is well known as an n-type superconductor with large physical anisotropies. In order to enhance the thermoelectric conversion performance, we have prepared the SCCO epitaxial films and controlled a crystallographic orientation, a carrier concentration and an introduction of nano-structures. The SCCO films and nano-structures consisting of CeO2 were fabricated using pulsed laser deposition method on SrTiO3 single crystalline substrates. Due to the orientation control and the optimization of carrier concentration, a low resistivity and a high Seebeck coefficient were achieved, and a power factor (PF) reached 1.14×10−3 W/mK2 at 323 K in the SCCO film with x × = 0.02. In addition, we measured the nano-structural effect on the PF of SCCO films. As a result, the PF showed a maximum in the film on a certain shape of the nano-structures. We speculate that the low resistivity was achieved by a formation of high Ce concentration layer near the interface between film and nano-structure.
Reversible Electrical Field-Induced Formation of Ruddlesden-Popper Phases in Strontium Titanate at Room Temperature
Authors: Meyer Dirk Carl , Levin Alexandr A. , Leisegang Tilmann , Gutmann Emanuel , Reibold Marianne , Paufler Peter , Pompe Wolfgang 
Published: April 2011

ABSTRACTOn base of the structural characteristics of near-surface regions of a SrTiO3 (001) (STO (001)) single-crystal plate revealed by means of wide-angle X-ray scattering (WAXS), X-ray fluorescence spectroscopy and high-resolution transmission electron microscopy, structural changes in the STO (001) single-crystal plate under the influence of an external electric field at room temperature can be described as the tunable and reversible formation of Ruddlesden-Popper-phases of the quasi-binary system SrO-TiO2. The WAXS behavior implies the use of the reversible phase-transition for adaptive X-ray optics.
Carbon Nanotubes: Research and Instrumentation For Undergraduate Students
Authors: Dillingham T. Randy , Porter Tim , Vail Tim , Hartzell Cynthia , Sellers Marilee 
Published: April 2011

ABSTRACTA team of faculty at Northern Arizona University (a predominantly undergraduate institution) have joined forces to develop a cross-disciplinary course for sophomore level science students in nanotechnology and the associated instrumentation with an overarching theme centered around carbon nanotubes. Research laboratories with various analytical capabilities were utilized from the Departments of Biology, Chemistry, and Physics and Astronomy. Specifically, the techniques that were used included scanning electron microscopy, x-ray photoelectron spectroscopy, nuclear magnetic resonance, and micro-sensor technology. The course content, the student activities and the initial experience in developing and team-teaching the course are described.
The Nanoscience Undergraduate Education (NUE) Program at James Madison University
Authors: Augustine Brian H , Reisner Barbara A. , Caran Kevin L. 
Published: April 2011

ABSTRACTWork has been underway at JMU in the Department of Chemistry through an NSF-NUE grant to develop an evolutionary approach to curriculum development across the undergraduate chemistry curriculum. Preliminary assessment data suggests that there exists a profound misunderstanding amongst graduating chemistry majors about basic aspects of nanotechnology as revealed by the NAI. Specifically, there are misconceptions about the sizes of and forces acting on the molecular-scale which is fundamental to any deep understanding of nanometer-scale phenomena. This is particularly alarming since senior-level undergraduate students majoring in chemistry should have a clearer understanding of molecular interactions than other STEM disciplines. A more careful, coordinated and sustained approach to teaching nanometer-scale phenomena must be undertaken in order to address these misconceptions and better prepare students the future workforce in nanoscience and nanotechnology.
European Activities in Nanoscience Education and Training
Authors: Baraton Marie-Isabelle , Monk Raymond , Tomellini Renzo 
Published: April 2011

ABSTRACTThis paper reviews salient features of the European initiatives to promote education in the field of nanosciences and nanotechnologies. Not only funding issues but also inherent cultural specificities are taken into account to evaluate the strengths and weaknesses of the European model to take up the challenge of the global economy. Multidisciplinarity and mobility of researchers appear to be key to foster excellence, whereas a reappraisal of curricula is necessary.
Influence of the Ge Dose in Ion-implanted SiO2 Layers on the Related Nanocrystal-memory Properties
Authors: Duguay Sébastien , Grob Jean-Jacques , Slaoui Abdelilah , Kern Philippe 
Published: April 2011

ABSTRACTThin silicon dioxide (SiO2) on Si layers with embedded germanium nanocrystals (Ge-ncs) were fabricated using 74Ge+-implantation at 15 keV and subsequent annealing. Transmission electron microscopy and Rutherford backscattering spectrometry have been used to study the Ge redistribution in the SiO2 films as a function of implantation dose under specific annealing conditions. At low implantation doses, Germanium is found to segregate at the Si/SiO2 interface leading to poor electrical properties. At higher doses and when the disorder limit of one displacement per atom is reached at the interface, transmission electron microscopy revealed the formation of a Ge-nc layer array located close to the Si/SiO2 interface and an another one inside the SiO2 host material. This near-interface high density (>1012 ncs/cm2) nc-layer is found to act as a floating gate embedded within the silicon dioxide. Capacitance-voltage measurements performed on metal-oxide-semiconductor structures containing such implanted SiO2 layers show significant memory properties (few volts hysteresis) at low programming voltages (<|10V|) due to the presence of Ge-ncs near the Si/SiO2 interface
Combinatorial Studies for High Density Si and Ge Nanoparticle Arrays
Authors: Stanley Scott K. , Ekerdt John G. 
Published: April 2011

ABSTRACTA simple combinatorial approach for studying chemical and physical vapor deposition (CVD and PVD) nanoparticle growth is presented utilizing temperature and precursor flux gradients across sample surfaces. Large temperature gradients (450-700 °C) are induced covering the entire range of interest for most CVD and PVD processes. Precursor flux gradients may also be introduced simultaneously or separately using a tungsten cracking filament mounted on a translation arm. Theory and calibration experiments are explained and results from a study on Ge nanoparticle growth on HfO2 surfaces are presented and analyzed. This method drastically decreases experimental time required to investigate nanoparticle growth and identify optimum deposition conditions. Furthermore, this approach greatly facilitates preparation of library samples containing a wide range (several orders of magnitude) in variation of nanoparticle sizes, density, and composition for subsequent studies.
Thermo-Electrical Analysis of an Optoelectronic Modulator Integrated in a SOI Rib Waveguide Operating in the Gb/s Regime
Authors: Iodice Mario , Coppola Giuseppe , Zaccuri Rocco Cristian 
Published: April 2011

ABSTRACTSilicon is the most diffused material for microelectronic industry and, in recent times, it is becoming more and more widespread in integrated optic and optoelectronic fields. We present the thermo-electro-optical analysis of an integrated waveguide-vanishing-based optical modulator based on free-carrier dispersion effect, realizable on standard SOI wafer. The optical behavior is based on the vanishing of the lateral confinement in the rib region, and consequent cut-off of the propagating mode. Results show that an optical modulation depth close to 100% can be reached with a bandwidth of about 154 MHz. Smart electrical driving, that is an injection overdrive of a few volts for a very short time, allows to reach total ON-OFF switching time of about 860 ps. For that bias scheme the fall transient is then limiting the whole dynamic and the resulting bit rate in a pure digital modulation scheme is about 1.2 Gb/s
Fabrication and Characterization of Thin-Film Metal-Insulator-Metal Diode for use in Rectenna as Infrared Detector
Authors: Krishnan Subramanian , Bhansali Shekhar , Buckle Kenneth , Stefanakos Elias 
Published: April 2011

ABSTRACTUncooled Infrared detectors with high sensitivity and shorter response times are preferred as through the wall detection device. An alternate approach for making these sensors, being pursued by us is to use the concept of rectenna with tunnel diodes. Successful fabrication of such high frequency switching diodes with antenna as detectors, offer a much faster response time than existing bolometer. This paper presents the fabrication and characterization of thin-film MIM diode for use in rectenna as an Infrared detector. MIM diodes operate on the basis of quantum mechanical phenomenon, i.e., when a sufficiently thin barrier (<5nm) is sandwiched between two electrodes, current can flow between them by means of tunnelling. This tunnelling probability increases with a decrease in the dielectric barrier height and the separation distance. The MIM diodes were fabricated with asymmetric electrodes with 1μm2 contact areas with cut-off frequency ∼0.1THz. The electrodes of the Ni-NiO-Cr MIM diodes have been fabricated through Photolithography, e-beam lithography, followed by conventional lift-off process. The dielectric layer (NiO) was deposited through plasma oxidation to obtain 2nm thin films. The composition and the thickness of the insulator layer are characterized by metrological tools like SEM and Spectroscopic Ellipsometer. The diode characteristics presented in this paper have been found to be stable and reproducible with the established fabrication conditions. Electrical behaviour (I-V) of the MIM junctions were investigated and compared with the theoretical tunnelling characteristics of the Ni-NiO-Cr MIM diodes. For devices with such non-linear electrodes, excellent agreement is obtained between the measured and the calculated result with the forward bias current as 0.8mA at 0.2V and the reverse bias current as −0.2mA at −0.2V.
NASICON-like phases in ScPO4-Na3PO4-Li3PO4 quasiternary system
Authors: Zhuravleva Mariya , Zakalyukin Ruslan , Fomichev Valeriy , Novoselov Andrey , Yoshikawa Akira , Fukuda Tsuguo , Zimina Galina 
Published: April 2011

ABSTRACTPhase formation in ternary system of complex Sc, Na and Li phosphates was studied at 950°C and synthesis of new phases of definite composition was carried out. Obtained samples were investigated with X-ray powder diffraction, infrared and impedance spectroscopy. Compositions of fields of homogeneity with the NASICON-like structure were discovered. Temperature dependency of ionic conductivity was measured.
Electrical Characterization of Polyfluorene-Based Metal-Insulator-Semiconductor Diodes
Authors: Yun M. , Arif M. , Gangopadhyay S. , Guha S. 
Published: April 2011

ABSTRACTPolyfluorenes (PFs) have emerged as a promising family of blue polymer light-emitting diodes (PLED) due to their high electroluminescence quantum yield. Metal-insulator-semiconductor (MIS) diodes are the two terminal analogues of thin film transistors sharing the same basic layer structure. We have investigated two different structures based on poly [9,9'-(di 2-ethylhexyl)fluorene] (PF2/6), a MIS diode and a hole-only PLED. The MIS diodes were fabricated with the PF2/6 layer on p+ Si /Al2O3 substrates, and were characterized by means of capacitance-voltage (C-V) measurements as a function of frequency. From C-V measurements, the unintentional doping density is evaluated as ∼5.7×1017 cm−3 at frequencies above 20 kHz. The interface trap density is estimated as ∼7.2×1011 eV−1cm−2 at 10 kHz. Current-voltage measurements of PF2/6-based PLEDs shows a shallow trap space-charge-limited conduction from which the energy of the traps and hole mobilities are estimated.
Design of a Passive-Matrix Smart Window by the Conjugated Polymer Electrochromics
Authors: Furukawa Rei , Xu Chunye , Taya Minoru 
Published: April 2011

ABSTRACTPreliminary development towards passive matrix Electrochromic (EC) device in conjugated EC polymer system is discussed. High contrast ratio of dark and bleached pixels is obtained by modification of counter and working electrode capacitance ratio and spacer geometry. Mask patterning and laminar electropolymerization for multicolor EC system application is discussed.
Probing Electronic Properties of dendritic Ruthenium Complex bound to Single Walled Carbon Nanotubes
Authors: Chaturvedi Harsh , Poler Jordan 
Published: April 2011

ABSTRACTWe have functionalized single walled carbon nanotubes (SWNTs) using ruthenium centered organometallic supramolecular dendritic complexes. These dendrimers have multiple binding sites with chemically specified chirality. Most importantly, they are mechanically rigid. We have fabricated field effect transistors (FET) using these functionalized SWNTs. Devices were processed with standard optical lithography and high resolution e-beam lithography. We are using FET response of these devices to study charge injection into the nanotubes and the resultant effect on the tube's transport properties. Organometallic based molecular adsorbents onto the nanotubes effect the transistor response. These functionalized tubes change their majority carriers from holes to electrons in these FETs. We believe this is due to charge transfer from the metal center through the ligand and finally onto the nanotube. This results in the potential for optically altering the carrier density, and therefore the transport properties of the nanotubes.
Low-Temperature Solid-Phase Epitaxy of Defect-Free Aluminum p+-doped Silicon for Nanoscale Device Applications
Authors: Civale Yann , Nanver Lis K. , Hadley Peter , Goudena Egbert J. G. , van Zeijl Henk W. , Schellevis Hugo 
Published: April 2011

ABSTRACTA solid phase epitaxy (SPE) technique was developed to grow p+ aluminum-doped crystalline Si in a fully CMOS compatible process. This paper describes the experimental conditions leading to the selective growth of nanoscale single crystals where the location and dimensions are well controlled, even in the sub-100 nm range. The SPE Si crystals are defined by conventional lithography, show excellent electrical characteristics, and are uniform over the whole wafer. Fifty nanometer thick p+ SPE Si crystals were used to fabricate p+-n diodes and p+-n-p bipolar junction transistors. The high quality of the SPE Si and the remarkable control of the whole process, even in the sub-100 nm range, make this module directly usable for Si-based nanodevices.
How Many Fe layers Cause TMR?
Authors: Heiliger Christian , Zahn Peter , Mertig Ingrid 
Published: April 2011

ABSTRACTThe influence of the structural properties of the leads of planar tunnel junctions on the tunneling current is investigated by means of ab initio electronic structure calculations. In particular, a NM/Fe/MgO/Fe/NM tunnel junction with non-magnetic (NM) leads and finite Fe spacer layers between the leads and the MgO barrier is discussed. The conductance is calculated as a function of the number of Fe layers. The results show that even one iron layer next to the barrier is sufficient to obtain a high spin polarization and a high TMR ratio. This finding implies that similar results can be expected for tunnel junctions with nonmagnetic and even amorphous leads, if states of Δ1 symmetry are provided.
Alloy Synthesis by Atomic Layer Laminations for Read Sensor Applications
Authors: Lee Chih-Ling , Devasahayam Adrian J , Mao Ming 
Published: April 2011

ABSTRACTA novel method has been developed for synthesis of multi-element alloys by planetary magnetron sputter deposition techniques. The alloy is formed by alternating depositions of uniform ultra-thin component layers at a fraction of a mono-atomic layer, or atomic layer lamination. A minimal layer thickness of down to 0.1Å can be obtained such that the components can be mixed at atomic level forming a homogeneous alloy.A typical example is demonstrated here for the synthesis of CoxFe1−x alloys by alternating depositions of Co and Fe layers from pure element targets. The compositional dependence of the laminates basically reconstructs the well-known Slater-Pauling curve of the bulk CoxFe1−x alloys. The laminates exhibit a clear structural transition at Co compositions between 60 and 80 % from fcc phase to bcc phase, characteristic of bulk CoxFe1−x alloys. The novel atomic layer lamination has been successfully applied to the composition optimization of CoFe pinned layer with a best pinning strength at Co70Fe30 for exchange biased spin-valve films.
Controlled Synthesis of Zinc Selenide Nanostructures using Oil-Water-Amphiphilic Block Copolymer Liquid Crystals
Authors: Karanikolos Georgios N. , Alexandridis Paschalis , Mountziaris T. J. 
Published: April 2011

ABSTRACTA technique for simultaneous size and shape control of compound semiconductor nanostructures using poly (ethylene oxide)-poly (propylene oxide)-poly (ethylene oxide) block copolymer/water/p-xylene lyotropic liquid crystals as templates is reported. Luminescent quantum dots of ZnSe were grown in the spherical domains of reverse (water-in-oil) cubic liquid crystals, hollow nanospheres and hollow nanotubes were grown around the dispersed spherical and cylindrical oil domains of the normal (oil-in-water) cubic and hexagonal phases respectively, and free-standing quantum wells (nanoplates or nanolaminates) were grown in the lamellar liquid crystals. The ZnSe nuclei were formed at room temperature by a spontaneous and irreversible reaction between zinc acetate that was dissolved in the water phase, and hydrogen selenide that was allowed to diffuse into the liquid crystalline templates. The nanostructures were characterized by HR-TEM, XRD, and optical spectroscopy. The shape of the nanocrystals can be controlled by selecting the structure of the templating phase. The size of the nanocrystals can be controlled by the size of the nanodomains and the concentration of the zinc precursor in them.
Sintering of Silver Nanoparticles for the Formation of High Temperature Interconnect Joints
Authors: Murray A. J. , Jaroenapibal P. , Koene B. , Evoy S. 
Published: April 2011

ABSTRACTWe report the development of a metallic colloid sintering process enabling the creation of bonding layers at moderate temperatures ranging from 150°C to 300°C, and pressures lower than 5MPa. This colloidal n-propyl acetate dispersion of Ag nanoparticles, having an average size distribution of 103nm, was used in sintered interconnect fabrication. Open air sintering of a 10um thick film resulted in an average resistivity of 0.20·10−6 −0.30·10−6 Ωm. Film resistances were found to be as low as 0.18·10−6 Ωm. Independent test varying either pressure or temperature were correlated to ultimate shear strength and modulus. The analysis of a 1cm2 bond area resulted in a peak shear strength of 5.83 MPa and shear modulus of 346 MPa which occurred following bonding at 300°C with a pressure of 4.219 MPa.