bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Strain on the Tunability of Highly (100) Oriented Mn-doped Barium Strontium Stannate Titanate Thin Films
Authors: Lu Shengbo , Li Ngai Wing , Xu Zhengkui 
Published: April 2011

AbstractHighly (100)-oriented Mn-doped barium strontium stannate titanate thin films of a nominal composition (Ba0.7Sr0.3)(Sn0.2Ti0.8-xMnx)O3(Mn-BSSnT) (x=0%, 0.2%, 0.4%, 0.6% and 1%), were fabricated by pulsed laser deposition on (La0.7Sr0.3)O3/LaAlO3substrates. Both elastic strain and inhomogeneous strain were measured by x-ray diffraction techniques. Relationship between the strain and the dielectric properties of the Mn-BSSnT thin films were systematically investigated as a function of the Mn content. Our results show that the tunability is dependent upon not only the elastic strain induced by thermal expansion coefficient and lattice mismatch between the thin film and the substrate but also inhomogeneous strain induced by Mn doping. The tunability decreases with increasing inhomogeneous strain and can be easily manipulated by changing Mn doping content, which is beneficial to real tunable device applications.
The Effect of Bi-excess Surface Layers on BiFeO3 Thin Films Prepared by Chemical Solution Deposition
Authors: Nakamura Yoshitaka , Nakashima Seiji , Ricinschi Dan , Okuyama Masanori 
Published: April 2011

AbstractWe have investigated the effect of Bi-excess surface layers of stoichiometric BiFeO3 thin films prepared by chemical solution deposition. A stoichiometric BiFeO3 thin film with both the Bi-excess top and bottom surface layers shows improved crystallinity with the remanent polarization of 65 μC/cm2 at 80 K, which is larger than BiFeO3 film prepared by the same process using stoichiometric solution. These results are attributed to the reduction of the imperfect crystal at the interface between BiFeO3 film and electrode. Stoichiometric BiFeO3 thin film with Bi-excess top and bottom surface layers also reserves the magnetic property of stoichiometric film. Stoichiometric BiFeO3 thin films with Bi-excess surface layers are an effective way to obtain good multiferroic properties.
Improvements in the Conductivity of n-type ZnO Through Codoping with Al and In
Authors: Kirby Steven , van Dover R. B. 
Published: April 2011

AbstractZnO has been identified as a viable candidate to replace expensive Sn doped In2O3 due to its high transparency and good conductivity. ZnO has been doped with many elements including Al and In to achieve conductivities near 104 Ω−1cm−1. One of the limiting factors in improving the conductivity beyond this is the limited solubility of these dopants in ZnO. The effect of codoping ZnO with both Al and In has been studied using a combinatorial technique. Cosputtering from three elemental targets in the presence of oxygen allowed for a range of ZnO(Al, In) compositions to be deposited on a single substrate. A deposition temperature of 250°XC was used. The films were analyzed using x-ray diffraction, electron microprobe, four-point resistivity measurements, Hall measurements, and reflection and transmission spectroscopy at optical wavelengths. Films that were codoped with both Al and In were found to have a significantly improved conductivity compared to singly doped samples, resulting mainly from an increase in mobility. This has been attributed to improved atomic structure of the codoped film. Al3+ has an ionic radius smaller than that of Zn2+ while In3+ has a larger radius; it is speculated that codoping compensates for these differences, reducing stress fields. The lattice parameter of the codoped film reflects this compensation effect.
Solution-deposited ZnO-organic diodes with high current density and high frequency rectification under ambient conditions
Authors: Pal Bhola N , Sun Jia , Jung Byung Jun , Katz Howard E 
Published: April 2011

Abstractn-ZnO/p-Pentacene and n-ZnO/poly(bis(dodecyl)quaterthiophene) (p-PQT-12) vertical p-n junction diodes were prepared on ITO-coated glass. A continuous film of ZnO nanoparticles was grown on the ITO glass by dip-coating and subsequent heat treatment of a zinc acetate film. Pentacene was then thermally evaporated to form the ZnO/Pentacene diode, whereas PQT-12 was spin coated for the ZnO/PQT-12 diode. Based on the band energies of ZnO, pentacene and PQT-12, for efficient carrier injection, gold was chosen as the top electrode to complement the ITO for both diodes. The microstructures of ZnO and pentacene films are studied by AFM and show a layer of pentacene grains with about twice the extent of the underlying layer of ZnO grains, implying substantial interfacial contact between them The current density-voltage (J-V) measurement shows that the maximum current density for ZnO/Pentacene and ZnO/PQT12 are 160 A/cm2 and 350 A/cm2 respectively. The rectification was characterized by observation of full input-half output waves. Data indicate that these devices can operate up to frequencies of 20 MHz and 9 MHz for ZnO/Pentacene and ZnO/PQT12, respectively, under ambient environment conditions. This rectification frequency is higher than other reported organic and polymer Schottky diodes under these conditions. Turn on voltages of these diodes are also much lower than for the reported organic and polymer diodes.
Infrared Lattice Vibrations of Nitrogen-doped ZnO Thin Films
Authors: Hirai Makoto , Kumar Ashok 
Published: April 2011

AbstractNitrogen (N) is the most promising p-type dopant for zinc oxide (ZnO), and its bonding state must be governed by the substitution of N atoms into anion sites. We have synthesized un-doped ZnO and N-doped ZnO thin films by utilizing a pulsed laser deposition (PLD) method. The N-doped ZnO thin film possessed shorter c-axis length than the un-doped ZnO thin film. This fact seems to be owing to that Zn-N bond length is shorter than Zn-O bond length in wurtzite structure. Besides, from the result of Fourier transform infrared (FT-IR) measurement, the absorption peak of the N-doped ZnO thin film emerged at 406 cm−1, and was attributed to transverse optical (TO) phonon of E1 mode. The infrared lattice vibrations of the N-doped ZnO thin films can be induced by the complex factors consisting of not only the decreases in reduced mass and interionic distance, but also the increase in covalency.
Electrical Pumped ZnO UV Random Lasers
Authors: Yu S. , Leong Eunice Sok Ping 
Published: April 2011

AbstractThe realization of ZnO random cavities may be an appropriate approach to fabricate low-cost ZnO laser diodes as there is no stringent requirement in the design of the disordered media provided that they can sustain enough optical gain and feedback within the media to achieve closed-loop random lasing. However, ZnO random lasers suffer from some drawbacks such as relatively higher threshold than conventional lasers, lack of directionality and coherency light emission as well as the difficulty to realize electrically pumped ZnO random lasers. In this paper, a short review on the possibilities to realize low threshold directional electrically pumped ZnO random laser diodes.
Electrical Characterization of N+-implanted n-type ZnO Single Crystals: p-n Homojunction and Deep Level Defects
Authors: Gu Qilin , Dai Xuemin , Ling Chi-Chung , Xu Shijie , Lu Liwu , Brauer Gerhard , Anwand Wolfgang , Skorupa Wolfgang 
Published: April 2011

AbstractUnintentionally doped n-type ZnO single crystals were implanted by nitrogen ions with different fluences of 1013, 1014 and 1015 cm−2 respectively. ZnO p-n homojunction was successfully fabricated due to the formation of p-type layer after 650°C post-implantation annealing in air for 30 minutes. Further thermal evolution of deep level defects was studied through thermal annealing up to 1200°C. Electrical characterization techniques including current-voltage (I-V), capacitance-voltage (C-V), Deep Level Transient Spectroscopy (DLTS) and double-correlation DLTS (DDLTS) were used for investigating the control sample, all the as-implanted and annealed samples through Au/n-ZnO Schottky diodes as well as ZnO p-n junctions. Detailed electrical properties of fabricated devices and characteristics of implantation induced defects were analyzed based on plentiful DLTS spectra. Moreover, low-temperature photoluminescence experiments of all the as-implanted and annealed samples were performed and the correlation between results from electrical and optical characterizations was discussed.
Defects in bulk ZnO studied by steady-state and time-resolved photoluminescence
Authors: Reshchikov Michael A. 
Published: April 2011

AbstractUnintentionally doped bulk ZnO samples were grown by hydrothermal method in Tokyo Denpa Co. Ltd. (Japan) and MTI Corporation. At low temperatures the PL spectrum contained a very broad band with the peak position (between 2.0 and 2.4 eV) depending on the excitation intensity. Evolution of the PL spectrum after a pulse excitation revealed that the broad band is composed of an orange (OL) and green (GL) luminescence bands having maxima at 1.96 and ∼2.35 eV, respectively. The GL band dominated at times up to 1 ms and then disappeared. The OL band decayed as approximately t−1 over a wide time interval, and its spectrum could be recorded even 24 hours after the excitation source was switched off. The slow nonexponential decay of the OL band is attributed to transitions from shallow donors to a deep acceptor (donor-acceptor pair transitions).
A Unique Method of Forming GexSi1-x Thin-Films on Insulator
Authors: Hossain Khalid , Holland O. W. , Mishima T. D. , Santos M. B. , Duggan J. L. , McDaniel F. D. 
Published: April 2011

AbstractA unique process of fabricating a strained layer GexSi1−x on insulator is demonstrated. Such strained heterostructures are useful in the fabrication of high-mobility transistors. This technique incorporates well-established silicon processing technology e.g., ion implantation and thermal oxidation. A dilute GeSi layer is initially formed by implanting Ge+ into a silicon-on-insulator (SOI) substrate. Thermal oxidation segregates the Ge at the growing oxide interface to form a distinct GexSi1−x thin-film with a composition that can be tailored by controlling the oxidation parameters (e.g. temperature and oxidation ambient). In addition, the film thickness can be controlled by the implantation fluence, which is important since the film forms pseudomorphically below 2×1016 Ge/cm2. Continued oxidation consumes the underlying Si leaving the strained GeSi film encapsulated by the two oxide layers, i.e. the top thermal oxide and the buried oxide. Removal of the thermal oxide by a dilute HF etch completes the process. Strain relaxation can be achieved by either of two methods. One involves vacancy injection by ion implantation to introduce sufficient open volume within the film to compensate for the compressive strain. The other involves spontaneous relaxation of the film, which may depend, in part, upon the formation of GeO. If Ge is oxidized in the absence of Si, it evaporates as GeO(gas). Conditions under which this occurs will be discussed.
Electromigration Reliability in Nanoscale Cu Interconnects
Authors: Hu C.-K. , Gignac L. M. , Baker-O'Neal B. C. , Bonilla G. , Liniger E. G. , Flaitz P. L. 
Published: April 2011

AbstractElectromigration behavior in Cu damascene wires was studied for various Cu grain struc-tures. The grain size was modulated by Cu linewidth and thickness, and by adjusting the wafer annealing process step after Cu electroplating and before Cu chemical mechanical polishing. A larger variation of Cu grain size between the samples was achieved on CMOS 65 nm node tech-nology than previous nodes which was due to the finer line width and thinner metal thickness. The Cu lifetime and mass flow in samples with bamboo, near bamboo, bamboo-polycrystalline mixture, and polycrystalline grain structures were measured. The effects of a Cu(2.5 wt.% Ti) alloy seed, Cu surface pre-clean, and selective electroless CoWP deposition techniques on Cu electromigration were also observed and a significantly improved Cu lifetime was found. The electromigration activation energies for Cu in Cu(Ti) alloy, along Cu/amorphous a-SiCxNyHz in-terface and grain boundary were found to be 1.3, 0.95 and 0.79 ± 0.05 eV, respectively. In addition the Cu line size effect on the Cu conductivity for Cu area less than 4×104 nm2 was found to be a linear function of the Cu line area.
Basic Materials Studies of Lanthanide Halide Scintillators
Authors: Doty F. P. , McGregor Douglas , Harrison Mark , Findley Kip , Polichar Raulf , Yang Pin 
Published: April 2011

AbstractCerium and lanthanum tribromides and trichlorides form isomorphous alloys with the hexagonal UCl3 type structure, and have been shown to exhibit high luminosity and proportional response, making them attractive alternatives for room temperature gamma ray spectroscopy. However the fundamental physical and chemical properties of this system introduce challenges for material processing, scale-up, and detector fabrication. In particular, low fracture stress and perfect cleavage along prismatic planes cause profuse cracking during and after crystal growth, impeding efforts to scale this system for production of low cost, large diameter spectrometers. We have reported progress on basic materials science of the lanthanide halides. Studies to date have included thermomechanical and thermogravimetric analyses, hygroscopicity, yield strength, and fracture toughness. The observed mechanical properties pose challenging problems for material production and post processing; therefore, understanding mechanical behavior is key to fabricating large single crystals, and engineering of robust detectors and systems. Analysis of the symmetry and crystal structure of this system, including identification of densely-packed and electrically neutral planes with slip and cleavage, and comparison of relative formation and propagation energies for proposed slip systems, suggest possible mechanisms for deformation and crack initiation under stress. The low c/a ratio and low symmetry relative to traditional scintillators indicate limited and highly anisotropic plasticity cause redistribution of residual process stress to cleavage planes, initiating fracture. Ongoing work to develop fracture resistant lanthanide halides is presented.
Crystal Growth and Characterization of CdTe and Cd0.9Zn0.1Te for Nuclear Radiation Detectors
Authors: Mandal Krishna , Kang Sung H. , Choi Michael , Mertiri Alket , Pabst Gary W , Noblitt Caleb 
Published: April 2011

AbstractCdTe and Cd0.9Zn0.1Te (CZT) crystals have been studied extensively at EIC Laboratories, Inc. for various applications including x- and γ-ray imaging and high energy radiation detectors. The crystals were grown from in-house zone refined ultra pure precursor materials using a vertical Bridgman furnace. The growth process has been monitored, controlled and optimized by a computer simulation and modeling program (MASTRAPP). The grown crystals were thoroughly characterized after sequential surface passivations and post-growth annealing treatments with and without component overpressures. The infrared (IR) transmission images of the post-treated CdTe and CZT crystals showed average Te inclusion size of ∼10 μm for CdTe crystal and ∼8 μm for CZT crystal. The etch pit density was ≤ 5×104 cm−2 for CdTe and ≤ 3×104 cm−2 for CZT. Various planar and Frisch collar detectors were fabricated and evaluated. From the current-voltage measurements, the electrical resistivity was estimated to be ∼1.5×1010 Ω·cm for CdTe and 2-5×1011 Ω·cm for CZT. The Hecht analysis of electron and hole mobility-lifetime products (μτe and μτh) showed μτe=2×10−3 cm2/V (μτh=8×10−5 cm2/V) and μτ3-6×10−3 cm2/V (μτh=4-6×10−5 cm2/V) for CdTe and CZT, respectively. Final assessments of the detector performance have been carried out using 241Am (60 keV) and 137Cs (662 keV) energy sources and the results are presented in this paper.
X-ray Topography to Characterize Surface Damage on CdZnTe Crystals
Authors: Black David , Woicik Joseph , Duff Martine C. , Hunter Douglas B. , Burger Arnold , Groza Michael 
Published: April 2011

AbstractSynthetic CdZnTe or “CZT” crystals can be used for room temperature detection of α- and γ-radiation. Structural/morphological heterogeneities within CZT, such as twinning, secondary phases (often referred to as inclusions or precipitates), and polycrystallinity can affect detector performance. As part of a broader study using synchrotron radiation techniques to correlate detector performance to microstructure, x-ray topography (XRT) has been used to characterize CZT crystals. We have found that CZT crystals almost always have a variety of residual surface damage, which interferes with our ability to observe the underlying microstructure −for purposes of crystal quality evaluation. Specific structures are identifiable as resulting from fabrication processes and from handling and shipping of sample crystals. Etching was found to remove this damage; however, our studies have shown that the radiation detector performance of the etched surfaces was inferior to the as-polished surface due to higher surface currents which result in more peak tailing and less energy resolution. We have not fully investigated the effects of the various types of inducible damage on radiation detector performance.
High Temperature Functionalization and Surface Modification of Nanodiamond Powders
Authors: Mochalin Vadym N. , Osswald Sebastian , Portet Cristelle , Yushin Gleb , Hobson Christopher , Havel Mickael , Gogotsi Yury 
Published: April 2011

AbstractHigh temperature annealing in vacuum, air, hydrogen, chlorine, and ammonia are described as a means to change surface chemistry and phase composition of nanodiamond powders of three different grades, which have different sp2/sp3carbon ratios. The changes in surface chemistry and phase composition of the powders are analyzed using Raman spectroscopy and Fourier Transform Infra Red (FTIR) spectroscopy. Advantages and limitation of high-temperature treatment techniques as well as potential applications of the gas-treated nanodiamond powders are discussed.
Triggered Single-photon Source based on Photoluminescence of Nickel-related Colour Centres in CVD-grown Nanodiamonds
Authors: Wu E , Rabeau James , Treussart François , Jacques Vincent , Zeng Heping , Prawer Steven , Grangier Philippe , Roch Jean-François 
Published: April 2011

AbstractWe report on the realization of a solid-state single-photon source in the near infrared at room temperature. It is based on the photoluminescence of a single NE8 colour center in a CVD grown diamond nanocrystal. Antibunching has been observed in the fluorescence light under both continuous and pulsed excitation. Our source delivers 30 kcts/s single-photon pulses at an excitation repetition rate of 20 MHz.
Mechanical Effect on Oxygen Mobility in Yttria Stabilized Zirconia
Authors: Araki Wakako , Adachi Tadaharu 
Published: April 2011

AbstractThe mechanical effect on the oxygen ion mobility in zirconia stabilized with 8 mol% yttria was investigated in this study. A dynamic mechanical thermal analysis showed that the dynamic modulus decreased gradually with temperature while the mechanical loss had two peaks due to different relaxation mechanisms. From the comparison of activation energies between the ionic conductivity and the mechanical relaxation, the dominant factor for oxygen mobility was determined to be the migration of oxygen vacancies in the simple complexes. An impedance analysis under mechanical tensile-loading conditions showed that the mechanical load increased ionic conductivity by 6% at maximum.
Dilute Solution of H in bcc Ti35Cr65-xVx Alloys
Authors: Mazzolai Giovanni 
Published: April 2011

AbstractThe solubility of H in the solid solution phase of the Ti35Cr47V18 alloy has been investigated at high and low temperature. The Sieverts law has been found to hold for 808 K≤T≤1204 K and fail for 302 K≤T≤335 K. For H contents nH ≤0.07 (nH=H/Me) the partial molar enthalpy and partial non-configurational entropy at high temperature are:On heating the material under H2 gas pressures lower than 0.1 MPa H absorption only occurs above 700 K. Below this temperature, surface oxide films prevent H uptake. Thermal decomposition spectroscopy of the α phase carried out for nH≤0.24 exhibits a single peak whose temperature increases with decreasing nH owing to selective occupancy by H of energetically non-degenerate interstitial sites.
MgH2 by Gas Phase Condensation: Nanostructure Morphology and Hydrogen Sorption Behaviour
Authors: Bonetti Ennio , Callini Elsa , Montone Amelia , Pasquini Luca , Piscopiello Emanuela , Vittori Antisari Marco 
Published: April 2011

AbstractInert gas condensation was employed to prepare nanoparticles of Mg and MgH2 which morphology, clustering degree and structural stability have been investigated by X-ray diffraction and electron microscopy. Thermodynamic functional properties of the Mg and MgH2 nanostructured samples were investigated by high pressure differential scanning calorimetry. Some specific features of the morphology of the samples prepared by inert gas condensation are compared with powders obtained by ball milling through desorption kinetics behavior.
The Potential of Binary Lithium Magnesium Nitride - LiMgN for Hydrogen Storage Application
Authors: Lu Jun , Fang Zhigang Zak , Choi Young Joon , Sohn Hong Yong 
Published: April 2011

AbstractMetal hydrides and amides are potential candidate materials for hydrogen storage. Lithium- and magnesium-based material systems are among the most promising materials owing to their high hydrogen contents. In the present work, we investigated hydrogenation/dehydrogenation reactions of a binary nitride, LiMgN. LiMgN can be formed by a reaction of MgH2 with LiNH2 in 1:1 ratio. The reaction also releases approximately ∼ 8.1 wt% H2 (theoretical value is 8.2 wt%) between 160 and 220 °C. The reaction product LiMgN can be rehydrogenated by reacting with H2 under 2000 psi of hydrogen pressure and 160 °C with small amount of TiCl3 doping. TGA results showed that about 8.0 wt% of hydrogen was stored in TiCl3-doped LiMgN during the hydrogenation process. The reversible hydrogenation and dehydrogenation mechanisms involving LiMgN and H2 are discussed.
Radiation Induced Structural Changes in Normal Spinels
Authors: Simeone David , Baldinozzi Gianguido , Gosset Dominique , Mazerolles Leo , Thome Lionel 
Published: April 2011

AbstractIon irradiation induced phase transformations in three normal spinel compounds MgAl2O4, MgCr2O4and ZnAl2O4have been investigated by X-ray diffraction, Raman spectroscopy and Transmission Electron Microscopy. This work presents a unified framework to describe the radiation effects in normal spinels. Irradiation modifies the atomic and mesoscopic structures of theses spinels in different ways. At the atomic scale, it produces the inversion of the cations in the spinel structure which can always be described within its usual Fd-3m space group. At the mesoscopic scale, it produces microdomains, responsible for the important changes in the X-ray diffraction patterns.