bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrical Behavior of Nano-Scaled Interconnects
Authors: Engelhardt M. , Schindler G. , Steinhögl W. , Steinlesberger G. , Traving M. 
Published: April 2011

AbstractSub-lithographic copper damascene lines were fabricated to investigate already today the physical phenomena and scaling limits of metallic conductors in the metallization systems of chip generations which are believed to be in production 10 years from now and later. Using standard manufacturing processes and state-of-the-art process tools, including standard lithography tools, narrow copper lines were fabricated at the expense of a relaxed pitch by use of a removable spacer technique. These copper nano interconnects were passivated and subjected to electrical measurements. Our results show that continuous down scaling to increase device performance will result in an unfavorable increase of the electrical resistivity of copper in stateof-the-art metallization schemes. Electrical measurements over a wide range of temperatures down to cryogenic temperatures reveal the limited potential of cooling to reduce resistivity of conductors as lateral dimensions will be shrinked down to the sub-100nm regime. By down scaling of copper diffusion barriers in damascene trenches, barrier functionality was demonstrated after high temperature anneals and excessive bias-temperature stress tests for films meeting or even exceeding end-of-roadmap thickness requirements. An analysis of the temperature dependence of the leakage current measured at very high electric fields applied between neighboring damascene lines suggests the conduction mechanism in the SiO2 used as intermetal dielectric to be Frenkel-Poole type rather than Schottky emission. Electromigration life times of sub-100nm copper lines embedded in oxide were found to be comparable with those obtained for similar structures fabricated with today's feature sizes.
Conducting Polypyrrole-based Field Effect Transistors Fabricated by Spin Coating and Inkjet Printing
Authors: Xue Fengliang , Su Yi , Varahramyan Kody 
Published: April 2011

AbstractSpin coating and inkjet printing are two major deposition techniques for flexible polymer plastic electronics. This paper presents polymer field effect transistors (FET) fabricated by these two techniques using conducting poylmer polypyrole (PPy) as a semiconductor material. These thin film polymer field effect transistors operate in the depletion mode. The field effect mobilities are calculated to be 0.045 cm2 V−1s−1 and 0.036 cm2 V−1s−1, and transconductances are 0.104 νS and 0.096 νS at saturation region of the I-V curves for the spin coated and the inkjet printed transistors, respectively. The measured turn-off threshold voltage is around 20 V for both the spin coated and inkjet printed PPy FET transistors. The device performance of the spin coated transistors is slightly better than that of the inkjet printed transistors. This is mainly due to high surface roughness of the printed polymer film and printed dot boundaries, leading to low charge carrier mobility in the printed polymer FET transistors.
Fabrication Techniques for the Processing of Adhesiveless ULTEM® Polyetherimide Dielectric Film
Authors: Durocher Kevin M. , Dris Irene , Goodwin Stacey , Abbatiello Nicholas 
Published: April 2011

AbstractFlexible printed circuits are a technology and product enabler for miniature, high density electronic systems, especially mobile communications and automotive applications. Over the past ten years, flexible printed circuit densities have increased, dramatically, while the area they occupy has decreased. The ever shrinking circuit form factor and increasing I/O and interconnect densities are driving flex circuit configurations from single sided to double sided constructions. In addition, the need for high performance steers circuit construction towards thinner dielectrics. Adhesiveless flex circuit constructions, for example, enable direct metal and lamination bonding without the use of added adhesive materials. Removing adhesive layers, such as epoxies or acrylics allows for a thinner more flexible device with a homogeneous dielectric stack (e.g., all polyimide construction), resulting in superior electrical performance. High resolution flexible circuit processes established using General Electric ULTEM [registered trademark] polyetherimide materials have shown ULTEM resin to have excellent electrical properties including dielectric constant and dissipation factor. Adhesiveless single and double sided flexible circuits have been fabricated and tested for performance (electrical, mechanical, thermal) and reliability (thermal cycling, tear propagation, flexural endurance, and solderability). Critical flex circuit fabrication processes such as metal adhesion, micro-via formation, lamination, photolithography, and module singulation have been evaluated. This paper addresses the key steps for flexible substrate fabrication describing the key advantages and disadvantages of the approach.
Tetrahedra from Aryleneethenylenes – From small Molecules to Luminescent Glasses
Authors: Detert H. , Sadovski O. , Sugiono Erli 
Published: April 2011

AbstractThe fourfold Horner olefination of tetraphenylmethane or –silane with fourp-methyl- phosphonate groups and a variety of aromatic aldehydes with donor groups or extended conjugated systems results in the formation of tetrahedra from four chromophores connected via a central atom. Electronic spectra in solution reveal an electronic interaction between the π-systems. In the solid state, the emission of compounds with a dense packing is nearly identical to the solution spectra, more open structures show significant red shifts. The emission of scaffolds with 1-styrylpyrene chromophores is nearly completely quenched. Most of these tetrahedra are thermally stable up to 420°C. Depending on the diameter of the scaffold, glass transitions occur between 99°C and 169°C.
Polymer Electrodes for Flexible Organic Light-Emitting Devices
Authors: Kim Woohong , Palilis Leonidas C. , Mäkinen Antti J. , Kim Heungsoo , Uchida Manabu , Kafafi Zakya H. 
Published: April 2011

AbstractWe report a high luminance and low operating voltage molecular organic light-emitting diode (MOLED) using a conducting polymer hole-injecting electrode (anode) on a plastic substrate. A dramatic improvement in the rectification ratio is observed upon the insertion of a buffer layer between the conducting polymer anode and the organic hole-transporting layer (HTL). Micro-shorts leading to a leakage current caused by the non-uniformity of the polymer film are greatly reduced. Atomic force microscope (AFM) images show a much smoother surface of the polymer anode/buffer layer relative to that of the bare polymer film. A slight increase (0.3eV ± 0.2eV) in the work function of the polymer anode upon the addition of the buffer layer is also measured. A simple method of patterning the conducting polymer electrode on various substrates including plastics is also reported. This approach conveniently provides finely patterned conducting polymer films with νm resolution while maintaining their intrinsic electrical and optical properties such as the surface sheet resistance and the optical transmittance.
Effect of strain and growth morphology on the evolution of the domain structure of ferromagnetic manganites
Authors: Miller Holly , Higgins J. S. , Mukovskii Y. , Greene R. L. , Biswas Amlan 
Published: April 2011

AbstractThe effect of strain on the surface magnetism of the manganite La0.7Sr0.3MnO3 has been studied as a function of temperature, using magnetic force microscopy. The non- uniform strain distribution in the film leads to a two-phase coexistence between ferromagnetic and non-ferromagnetic phases. This leads to a reduction of the surface curie temperature and the formation of ferromagnetic islands. Methods of controlling this behavior in order to fabricate arrays of magnetic nanodots are discussed.
The Definition of Multiple Bandgaps in Quantum-Dot Material by Intermixing
Authors: Catrina Bryce A. , Marsh John H. , Yanson Dan A. , Kowalski Olek P. , Kim Shin-Sung 
Published: April 2011

ABSTRACTWe present the recent progress in the intermixing of InGaAs/GaAs quantum dot (QD) material. Quantum dot intermixing (QDI) allows the tuning of the energy bandgap in selected areas of the wafer or optoelectronic device, thus modifying its emission or absorption properties, in much the same way as in quantum well (QW) material. QDI has recently received increasing interest, as it combines bandgap engineering with the predicted advantages that quantum dots offer, such as low temperature-sensitivity of threshold current, high modulation frequency and low chirp.We have applied the dielectric-cap-based techniques that were originally developed for QW structures, to the intermixing of InGaAs/GaAs/AlGaAs QD material with an emission wavelength of 1280 nm. Intermixing was achieved by sputtering a QDI-enhancing cap in some areas, and a QDI-suppressing cap in other areas, followed by a high-temperature anneal cycle. Extremely large bandgap blue-shifts of up to 280 nm have been obtained with an anneal temperature of 800 °C. The shifts were inferred from the photoluminescence (PL) spectra measured at 77 K under red-laser excitation.To be of use in many applications, QDI must be able to provide a multiplicity of bandgaps on a single substrate. Multiple bandgaps can be created by varying the thickness of the QDI-enhancing cap, repeating the anneal cycle several times, or varying the coverage density of QDI-enhancing features over that of QDI-suppressing ones. The latter approach, termed selective intermixing in selected areas (SISA), involves the deposition of QDI-enhancing patterns of various area fill factors, which, upon annealing, will cause different degrees of intermixing in the underlying regions.To demonstrate the SISA process in the QD material, we defined patterns containing lines and squares of various sizes (3 - 100 μm) and area fill factors (5% - 95%). The wafer was then annealed at 725 °C for 1 minute. As expected, the observed bandgap shifts were commensurate with the fill factor, with a 5% coverage providing a minimum shift (0 - 10 nm) and ∼40% a maximum one (∼ 120 nm). At fill factors above 40%, the shifts appeared to saturate and even decrease slightly. The effect of the feature size and shape was not very pronounced, with smaller features generating somewhat larger shifts. This may be due to the fabrication-related size bias that will have the strongest effect on the fill factor of smaller features. The PL spectra measured from patterns of large-size features (20 μm or more) often had a lopsided shape and broader peak width, which may be attributed to the limited spatial resolution of the measurement probe.
Electrical and dielectric behavior of Pb(Mg1/4Ni1/4W1/2)O3 ceramics
Authors: Júnior Adolfo Franco 
Published: April 2011

ABSTRACTIn this study full dense polycrystalline samples of Pb(Mg1/4Ni1/4W1/2)O3 have been sintered by solid-state reaction. X-ray data showed the formation of a single-phase new compound with unit cell parameters a = 9.8045 (25) Å, b = 13.1280(25) Å and c = 14.4207 (25) Å. Scanning electron microscopy (SEM) was used to evaluate the microstructures of sintered specimens. Dielectric constant and loss as function of frequency were investigated.
Preparation of Ultraviolet Light Emitting ZnO Nanoparticles Via a Novel Synthesis Route
Authors: Li Yuntao , Yang Richard D. , Tripathy S. , Sue H.-J. , Miyatake N. , Nishimura R. 
Published: April 2011

ABSTRACTA new synthesis methodology is utilized to prepare ZnO nanoparticles with a narrow size distribution between 2 to 4 nm. The particle growth is found to be reaction time dependent. The dry powders of ZnO nanoparticles show a strong blue-shifted near-band-edge ultraviolet emission, and the size and size distribution of the particles did not exhibit noticeable change during solvent evaporation. Raman spectra show ZnO E22 (TO) phonon mode and other vibration modes that are attributed to the bound acetate group. The CO stretching mode in the Raman spectra is red-shifted to 1401 cm-1, indicating a strong adsorption of the acetate ligands onto ZnO surfaces.
Compositional Ordering in InxGa1-xN and its influence on optical properties
Authors: Liliental-Weber Z. , Zakharov D. N. , Yu K. M. , Wu J. , Li S. X. , Ager J.W. , Walukiewicz W. , Haller E.E. , Lu H. , Schaff W. J. 
Published: April 2011

ABSTRACTInxGa1-x N layers grown with compositions with the predicted miscibility gap have been studied using Transmission Electron Microscopy (TEM), x-ray diffraction and optical measurements (photoluminescence and absorption). The samples (0.34 < × < 0.8) were deposited by Molecular Beam Epitaxy at 800°C using 200 nm AlN buffer layer grown directly on sapphire substrates. Another sample with × = 0.34 was grown on a GaN buffer layer. Dislocation densities in the InGaN layers were typically in the mid-1010 cm−2 to1011 cm−2 range. Edge dislocations were the most prevalent. For In concentration × = 0.5 compositional ordering is observed leading to extra diffraction spots in electron and x-ray diffraction. The ordering was not observed for the sample with x=0.34 grown on GaN. Based on TEM measurements the estimated period of ordering Δ was about Δ = 45 Å for × = 0.5 and Δ = 65Å for × = 0.78. The sample with × = 0.5 had the highest dislocation density. In addition to the presence of threading dislocations two types of domain boundaries on (0001) and (0110) planes were also observed in this sample. This sample has a broader photoluminescence (PL) that is redshifted compared to the absorption edge (“Stokes shift”).
Ammonothermal growth of GaN utilizing negative temperature dependence of solubility in basic ammonia
Authors: Hashimoto Tadao , Fujito Kenji , Wu Feng , Haskell Benjamin A. , Fini Paul T. , Speck James S. , Nakamura Shuji 
Published: April 2011

ABSTRACTAmmonothermal growth of GaN was studied to determine its eventual utility for mass production of GaN bulk crystals. Dissolution of GaN in supercritical ammonia with 1 M NaNH2 was investigated through a weight loss method. The time dependence of the weight loss was examined at 500°C and 525°C. Since the weight loss did not reach saturation as a function of time, the solubility limit was not realized. However, experiments demonstrate that GaN has a negative temperature dependence of solubility in supercritical ammonobasic solutions. Based on this result, GaN was grown via fluid transport from metallic Ga to a free-standing GaN single crystal seed by placing the seed crystal in a higher temperature zone and the nutrient in a lower temperature zone. GaN films with thickness of 5 μm (Ga face) and 4 μm (N face) were simultaneously grown on the seed in three days. The surface morphology, optical property, and defect density were found to be different for films on Ga face and N face.
Strain-Induced Effects on the Resonant Tunnelling of Holes in Zinc-Blende AlyGa1-yN/AlxGa1-xN/AlyGa1-yN Heterostructures
Authors: Meguenni C. , Zitouni K. , Mokdad N. , Kadri A. 
Published: April 2011

ABSTRACTWe present a multi-band effective mass kP study of built-in strain induced effects on the resonant tunnelling of holes in Zinc-Blende AlyGa1-yN/AlxGa1-xN/AlyGa1-yN Double Barrier Resonant Tunnelling Heterostructures with 0 ≤ × ≤ 0.15 and 0.2 ≤ y ≤ 0.3. We show the influence of the SH split-off band on the resonant tunnelling of light (LH) and heavy (HH) holes through the strain-induced mixing of valence subband states. This valence subbands coupling is shown to result in a broadening of the resonance peaks in SL, LS hole transmission curves and a smearing out of the corresponding resonance peaks in the tunnel current. This effect is shown to decrease with increasing biaxial compression (decreasing x) and is minimum at x=0 in an Al.20Ga.80N/GaN/Al.20Ga.80N heterostructure.
Oxygen related shallow acceptor in GaN
Authors: Monemar B. , Paskov P. P. , Tuomisto F. , Saarinen K. , Iwaya M. , Kamiyama S. , Amano H. , Akasaki I. , Kimura S. 
Published: April 2011

ABSTRACTWe report on deliberate O doping of GaN epitaxial layers during MOCVD growth, using H2O and CO2 as precursors. The photoluminescence spectra show a dominant 3.27 eV emission at 2 K known to be a donor-acceptor pair (DAP) transition. In our samples the intensity of this DAP spectrum correlates with the commonly observed 3.466 eV acceptor bound exciton (ABE) peak, suggesting these spectra are related to the same acceptor. The general correlation of these acceptor spectra with O concentration (as established with SIMS data) suggest that the acceptor is O-related, most likely a VGa-O complex. The concentration was measured with positron annihilation spectroscopy and found to be in the 1016 cm−3 -1017 cm−3 range in different samples. Considering previous results the identity of this residual acceptor is suggested to be a VGa-O-H complex. Previous suggestions that this acceptor is related to Mg, Si or C are discussed and found to be less likely.
Cathodoluminescence of Praseodymium doped AlN, GaN and turbo static BN.
Authors: Maqbool Muhammad , Richardson H. H. , Kordesch M. E. 
Published: April 2011

ABSTRACTPraseodymium (Pr) doped aluminum nitride (AlN), gallium nitride (GaN) and boron nitride (BN) thin films deposited on Si (111) substrate are studied with cathodoluminescence. AlN:Pr and GaN:Pr films are deposited at 77 K and room temperature respectively while BN:Pr films at 750 K by reactive sputtering, using 100–200 Watts RF power, 5–10 mTorr nitrogen. Metal targets of Al and B with Pr and a liquid target of Ga with solid Pr are used. The dominant peaks observed in the visible range result from 3P0 → 3H4, 3P1→ 3H5, and 3P0 → 3F2 transitions in AlN:Pr, 3P0 → 3H4, 3P0 → 3H6, and 3P0 → 3F2 transitions in GaN:Pr and from 3P0 → 3H4, 3P1→ 3H5, 3P0 → 3H6, and 3P0 → 3F2 transitions in BN:Pr. Additional peaks are observed from AlN:Pr at 335 nm and 385 nm from 1S0 → 1D2 and 1S0 → 1I6 which are not observed in GaN:Pr and BN:Pr films.
Preparation of the atomically straight step-edge Si (111) substrates as templates for nanostructure formation
Authors: Yoshida Shunji , Sekiguchi Takeharu , Itoh Kohei M. 
Published: April 2011

ABSTRACTWe report on the experimental discovery that the distribution of kinks along steps on vicinal Si(111) surfaces depends on the direction of the dc current passed along the steps for resistive annealing. The as-cleaned Si(111) surface miscut ∼1° towards [112] has a small (<3°) unavoidable azimuthal deviation, which produces a number of kinks along the step-edges. When the azimuthal misorientation is from [112] towards [110] [110], dc current flowing in the direction [110] [110] climbing up the kinks straightens the step-edges as opposed to the current flowing in the opposite [110] [110]direction. During annealing around 800°C, the dc current in the direction climbing up the kinks straightens the steps. The up-climbing current direction transports and concentrates the kinks in a region outside the template area, leaving a kink-free atomic step-edge region as an ideal template for a variety of nanostructure formations. The straight step edges produced in this manner have uniform atomic configuration known as U(2, 0).
Pump-probe experiments on Er coupled Si-nanocrystals rib-loaded waveguides
Authors: Daldosso N. , Navarro-Urrios D. , Melchiorri M. , Pavesi L. , Gourbilleau F. , Carrada M. , Rizk R. , García C. , Pellegrino P. , Garrido B. , Cognolato L. 
Published: April 2011

ABSTRACTPump and probe experiments have been performed on Er-doped rib-loaded waveguides containing Si nanoclusters grown by reactive magnetron sputtering. An Er3+ absorption cross-section of about 5×10−21 cm2 has been found at 1534 nm by insertion losses measurements. Transmission measurements at 1310 nm under optical pumping (488 nm) shows a decreasing of the signal because of confined carrier absorption of the Si nanoclusters. Amplification experiments at 1535 nm evidence two pump power regimes: losses due to confined carrier absorption in the Si nanoclusters at low pump powers and signal amplification at high pump powers. For strong optical pumping, signal enhancement of about 1.2 dB/cm was observed.
Threshold Voltage Shift in Hetero-nanocystal Floating Gate Flash Memory
Authors: Zhu Yan , Zhao Dengtao , Li Ruigang , Liu Jianlin 
Published: April 2011

ABSTRACTThe threshold voltage shift of a p-channel Ge/Si hetero-nanocrystal floating gate memory device was investigated both numerically and phenomenologically. The numerical investigations, by solving 2-D Poisson-Boltzmann equation, show that the presence of the Ge on Si dot tremendously prolongs the retention time, reflected by the time decay behavior of the threshold voltage shift. The increase of the thickness of either Si or Ge dot will reduce the threshold voltage shift. The shift strongly depends on the dot density. Nevertheless, only a weak relation between the threshold voltage shift and the tunneling oxide thickness was found. A circuit model was then introduced to interpret the behavior of threshold voltage shift, which agrees well with the results of the numerical method.
Structural characterization and Coulomb blockade of a-SiNx/ nanocrystalline Si /a-SiNx asymmetric double-barrier structures
Authors: Wu L. C. , Dai M. , Huang X. F. , Han P. G. , Yu L. W. , Zou H. C. , Li W. , Chen K. J. 
Published: April 2011

ABSTRACTWe have fabricated a series of a-SiNx/nc-Si/a-SiNx double-barrier structural samples by plasma-enhanced chemical vapor deposition (PECVD) and subsequent thermal annealing technique. The micro-structural properties of the samples were studied by using Raman scattering spectroscopy, planar and cross-section transmission electron microscopy (TEM). The electrical properties of the samples were investigated by frequency dependence of capacitance voltage (C-V) measurements. Charging effect in the nc-Si was exhibited through the hysteresis phenomena of the C-V curve and explained by F-N tunneling. For the thicker SiNx barrier layer samples, Coulomb blockade effect was observed in C-V curve for the sample with thinner SiNx barrier layer, in which two capacitance peaks appeared, and explained by direct tunneling of electrons into the nc-Si through the tunneling SiNx layers. From the interval between the two peaks, the Coulomb charging energy of nc-Si dot was estimated.
Recent Results on the Road to a SiGe Quantum Cascade Laser
Authors: Borak Alex , Tsujino Soichiro , Falub Claudiu , Scheinert Maxi , Diehl Laurent , Müller Elizabeth , Sigg Hans , Grützmacher Detlev , Gennser Ulf , Sagnes Isabelle , Blunier Stefan , Fromherz Thomas , Campidelli Yves , Kermarrec Oliver , Bensahel Daniel , Faist Jerome 
Published: April 2011

ABSTRACTThe primary challenges in implementing a Si based quantum cascade laser are discussed. Intersubband absorption measurements were carried out on a series of modulation doped multiquantum well structures. The spectra were compared to the predictions of a 6 band k.p model, which confirmed the excellent accuracy of the model, and its ability to predict the bandstructures of more complicated cascade structures. A detailed structural analysis demonstrated excellent growth quality, with an interface roughness of < 0.4 nm. Electroluminescence measurements on cascade structures with doped contacts, processed as finger structures and waveguides of various sizes, enabled a quantitative analysis of the active region performance. The upper state lifetime τnr was ∼ 100 fs, leading to a total active region optical gain of ∼ 2 cm−1, a factor of ∼ 10 lower than the estimated total losses due to free carrier absorption. The total emitted power and the linewidth of the intersubband emission saturate above ∼ 6.5 kA/cm2, probably due to misalignment of the injector levels at high biases. The effect of leak currents and interspersed light hole states on the intersubband emission are considered.