bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphology of Ti37Al63 Thin-Films Deposited by Magnetron Sputtering
Authors: Theodore N. David , Kim Hyunchul C. , Gadre Kaustubh S. , Mayer James W. , Alford Terry L. 
Published: April 2011

AbstractTiAl based thin-films possess high oxidation-resistance and high melting points, making them possible candidates for application in electronics. The behavior of the films upon exposure to various temperatures is of interest for such application. In the present study, Ti37Al63 thin films were deposited onto SiO2 substrates using RF magnetron sputtering from a compound target. Anneals were performed in vacuum at temperatures ranging from 400 °C to 700 °C. The phases and microstructural behavior of the films were evaluated as a function of annealing. Microstructural behavior was correlated with resistivity changes in the films. The behavior of Ti-Al films as potential under-layers for silver metallization was also evaluated. The Ti-Al was observed to enhance the thermal stability of pure Al thin-films. The results are relevant for potential application of the films to electronics.
3-dimensional evaluation of nm-pores in porous low-k films using TEM stereoscopic / electron tomographic observation method
Authors: Shimanuki J. , Inoue Y. , Shimada M. , Ogawa S. 
Published: April 2011

AbstractStereoscopic and electron tomographic observation methods using Transmission Electron Microscope (TEM) were examined to characterize three-dimensionally a shape and size of pores and spatial distribution in porous low dielectric constant (low-k) films. In a case of TEM observation, nm size pores in an amorphous film are difficult to be imaged since contrast from the amorphous layer affect the pore imaging. An optimum image capture method at a modified electron beam condition was studied in which the amorphous contrast from the porous low-k film is weakened to enhance scattering contrast from the pores and a matrix. As a result, a stereoscopic observation and 3-D reconstruction images clarified that the shape of pores was not spherical but distorted and almost pores were partially connected. For measuring pore size and spatial distribution, connected pores were segmented into smaller pores by separating at the narrowest part. From images after segmentation, it is indicated that there existed more and larger pores at interfaces than a center area. It was found that the pores did not homogeneously distribute in the film but concentrated at the interfaces.
Coupling Between Precipitation and Plastic Deformation During Electromigration in a Passivated Al (0.5wt%Cu) Interconnect
Authors: Barabash R.I. , Ice G.E. , Tamura N. , Valek B.C. , Spolenak R. , Bravman J.C. , Patel J.R. 
Published: April 2011

AbstractIn the present paper the evolution of the dislocation structure during electromigration in different regions along the Al(Cu) interconnect line is considered. It is shown that plastic deformation increases in the regions close to cathode end of the interconnect line. A coupling between the dissolution, growth and re-precipitation of Al2Cu precipitates and the electromigration-induced plastic deformation of grains in interconnects is observed. Possible mechanism of the Cu doping effect on the improved electromigration resistance of the Al(Cu) interconnects is discussed.
MEMS Metallization
Authors: Lohmann Christian , Gottfried Knut , Bertz Andreas , Reuter Danny , Hiller Karla , Kuhn Michael , Gessner Thomas 
Published: April 2011

AbstractSilicon is the dominating material for the fabrication of MEMS devices, especially in high volume production. However, metals with their typical properties are used to enhance or enable the functionality of MEMS. In contrast to microelectronic technologies, not only the electrical but also the mechanical and optical behavior of metals could be helpful. New requirements in MEMS technologies demand optimized processes in metallization for the fabrication of microstructures.This paper presents some metallization applications and related technology development in the field of MEMS.
Interface Nanochemistry in Mg-Doped Al2O3
Authors: Petot-Ervas Georgette , Baldinozzi Gianguido , Petot Claude , Graham Mike J. , Sproule Irwin G. , Tebtoub Moussa , Raulot Jean-Marc 
Published: April 2011

AbstractIn this experimental paper the influence of the grain size, of the thermal history and of the nominal composition on the nanochemistry at the interfaces in α-alumina submicronic powders are analyzed. The consequences on the physical and chemical properties are also discussed. Nanocrystalline Mg-doped α-alumina powders (550 and 1650 ppm by wt MgO) were prepared by the alum process. These powders (10-400 nm) were characterized by X-ray diffraction, SEM, TEM, XPS and surface area measurements (BET). In agreement with BET analysis, SEM observations show that the grain size increases with annealing time and annealing temperature. This effect is less pronounced in the highly doped samples. The less doped samples are also less aggregated and sintering bridges between the grains are still observed. XPS shows that Mg segregates at the periphery of the grains on a depth ≤0.5 nm. The dopant segregation is stronger when the nominal amount of Mg increases, leading eventually to the formation of MgAl2O4 precipitates near the grain surface. It is possible to observe an increase of the dopant segregation with grain size in the low Mg concentration powders. Other impurities like Si or higher cooling rates also favour this Mg segregation. However, the rate of cooling is so effective that it can overshadow all the other parameters (grain size, impurities,…), suggesting that this is certainly the key parameter for obtaining a perfect sintering of these ceramics, as experimentally shown.
Recrystallization Processing of Cold-Rolled Nickel
Authors: Baker I. , Chang H. , Li J. 
Published: April 2011

AbstractWe have examined the effects of isothermal annealing, at a variety of temperatures, and directional annealing, under a range of conditions, on both primary recrystallization and secondary recrystallization in 90% cold-rolled 99.5% nickel of two different textures. The initial texture is shown to influence the rolling texture and, hence, the results of subsequent annealing. It was found that one alloy showed a cube texture after primary recrystallization, underwent abnormal grain growth upon annealing at high temperatures, and could be directionally (secondary) recrystallized to give large columnar grains. In contrast, the other alloy produce a weak cube texture after primary recrystallization, showed only normal grain growth upon annealing at higher temperatures, and could not be directionally annealed to produce columnar grains. The implications of these results are discussed for producing columnar grains.
Stereological Corrections for Grain Boundary Number Fractions in Three Dimensions
Authors: Reed Bryan W. , Kumar Mukul 
Published: April 2011

AbstractTwo-dimensional (2D) cross sections through three-dimensional (3D) polycrystalline materials present a biased picture of the statistical properties of grain boundary networks. These properties are essential to many practical applications such as grain boundary engineering. We show a simple correction that will partly correct for the sampling biases by removing the effect of the correlation between grain boundary type and grain boundary area. This correction alters number fraction estimates by as much as ∼60% for σ3 boundaries in the highly-twinned copper samples we consider. We also estimate the bias introduced by the correlation between boundary type and boundary shape, which for many materials represents perhaps a 10% shift in the measured statistics, so that the simple method we propose should correct for the majority of the bias in favorable cases.This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes.
Atomic Force Microscopy and Spectroscopy of Self-Assembled InAsSb Quantum Dots grown on InP Substrates by MOCVD
Authors: Sin Yongkun , Kim Hyun I. , Stupian Gary W. , Qiu Yueming 
Published: April 2011

ABSTRACTInAsSb quantum dot (QD) lasers are promising light sources with emission wavelengths beyond 2μm as recently demonstrated. We report the first detailed atomic force microscope (AFM) characterization of uncapped InAsSb quantum dots self-assembled on GaAs/In0.53Ga0.47As layers. These quantum dot structures are grown on (100) InP substrates by metal organic chemical vapor deposition (MOCVD). Growth conditions are chosen to maximize photoluminescence intensity and to obtain high output powers from Fabry-Perot lasers with one stack of InAsSb QDs. Conductive AFM is employed to simultaneously study topography, current image, and current-voltage (I-V) characteristics from various InAs1-ySby QDs with y varied between 0 and 0.25. Typical dot density is 4–5×1010/cm2 and dots are estimated to have a lateral dimension at the base of ∼40nm and a height of 2–5nm. I-V characteristics measured from individual InAsSb QDs are compared to those from InAs QDs. Also reported are electronic properties including energy band gaps of InAs and InAsSb QDs.
Intersubband Transitions in In0.3 Ga0.7As/GaAs Multiple Quantum Dots of Varying Dot-Sizes
Authors: Chua Y. C. , Liang Jie , Passmore B. S. , DeCuir E. A. , Manasreh M. O. , Wang Zhiming , Salamo G. J. 
Published: April 2011

ABSTRACTThe optical absorption spectra of intersubband transitions in In0.3Ga0.7As/GaAs multiple quantum dots (MQDs) grown by molecular beam epitaxy were investigated. By varying the number of In0.3Ga0.7As monolayers deposited, a series of samples with varying dot sizes ranging from 10 – 50 monolayers were obtained. The quantum dots grown with size less than 15 monolayers or more than 50 monolayers did not yield any observable measurements of intersubband transition. This suggests that there exist a critical upper and lower limit of In0.3Ga0.7As quantum dots for infrared detectors. A wavelength range of 8.60 – 13.70 μm is achieved for structures grown with the above monolayers range. The theoretical line-shape of the intersubband transition absorption was compared to the experimental measurements. From the lineshape, it was deduced that bound-to-continuum transtition is present in thick quantum dots and bound-to-bound transition is present in thinly grown quantum dots.
Pt/Au and W/Pt/Au Schottky Contacts to Bulk n-ZnO.
Authors: Ip Kelly , Gila Brent , Onstine Andrea , Lambers Eric , Heo Young-Woo , Norton David , Pearton Stephen , LaRoche Jeffrey , Ren Fan 
Published: April 2011

ABSTRACTUV-ozone cleaning prior to metal deposition of either e-beam Pt contacts or sputtered W contacts on n-type single-crystal ZnO is found to significantly improve their rectifying characteristics. Pt contacts deposited directly on the as-received ZnO surface are Ohmic but show rectifying behavior with ozone cleaning. The Schottky barrier height of these Pt contacts was 0.70 eV, with ideality factor of 1.5 and a saturation current density of 6.2 × 10−6 A·cm−2. In contrast, the as-deposited W contacts are Ohmic, independent of the use of ozone cleaning. Post-deposition annealing at 700 °C produces rectifying behavior with Schottky barrier heights of 0.45 eV for control samples and 0.49 eV for those cleaned with ozone exposure. The improvement in rectifying properties of both the Pt contacts is related to removal of surface carbon contamination from the ZnO.
Short-Period Strain-balanced GaAs1-x Nx/InAs(N) Superlattices Lattice-matched to InP(001): a new material for 0.4–0.6 eV mid IR applications
Authors: Bhusal L. , Alemu A. , Freundlich A. 
Published: April 2011

ABSTRACTA theoretical and experimental investigation of electronic band structure (Γ-point) of strain balanced GaAs1-xNx/InAs1-xNx short period superlattice on InP is performed. A six-band Kane Hamiltonian and band anti-crossing models, modified for the strain effects are used to describe the electronic states of the highly strained zincblende GaAs1-xNx and InAs1-xNx ternaries. Operating wavelengths of these heterostructures are predicted to extend beyond 2 μm. Preliminary photoluminescence results of the chemical beam epitaxially grown sample are shown to be consistent with the theoretical predictions.
Vertical and in-plane electrical transport in InAs/InP semiconductor nanostructures
Authors: Vicaro K. O. , Bortoleto J. R. R. , Gutiérrez H. R. , Nieto L. , von Zuben A. A. G. , Seabra A. C. , Schulz P. A. , Cotta M. A. 
Published: April 2011

ABSTRACTVertical and in-plane electrical transport in InAs/InP semiconductors wires and dots have been investigated by conductive atomic force microscopy (C-AFM) and electrical measurements in processed devices. Localized I-V spectroscopy and spatially resolved current images (at constant bias), carried out using C-AFM in a controlled atmosphere at room temperature, show different conductances and threshold voltages for current onset on the two types of nanostructures. The processed devices were used in order to access the in-plane conductance of an assembly with a reduced number of nanostructures. On these devices, signature of two-level random telegraph noise (RTN) in the current behavior with time at constant bias is observed. These levels for electrical current can be associated to electrons removed from the wetting layer and trapped in dots and/or wires. A crossover from conduction through the continuum, associated to the wetting layer, to hopping within the nanostructures is observed with increasing temperature. This transport regime transition is confirmed by a “temperature-voltage” phase diagram.
Preparation and luminescent properties of SrS:Ce by addition of sulphur as a co-activator in SrSO4:Ce(SO4)2.4H2O by carbothermal reduction.
Authors: Thiyagarajan P. , Kottaisamy M. , Sethupathi K. , Rao M. S. R. 
Published: April 2011

ABSTRACTCe activated SrS has been prepared from SrSO4:Ce(SO4)2.4H2O by ecologically acceptable carbothermal reduction in the absence of inert gas and hazardous H2S environment. The mixtures were fired at 900°C to find out the feasibility of the reduction reaction. In order to understand the compensator behavior we tried with sulfur and various fluxes viz., NH4Cl, NaCl. The materials synthesized were characterized by XRD, photoluminescence emission (PL) and excitation spectroscopy (PLE) and SEM. The characterization results showed the formation of SrS at 900°C with an increase in luminescence intensity after the addition of sulfur as a co-activator. The bright blue-green emission observed at 480nm and 540nm corresponds to energy bands originating from 2T2g (5d) to 2F7/2, 2F5/2(4f) of Ce3+ transitions. The excitation spectrum shows a fundamental absorption of SrS host crystal lattice in the lower wavelength region at 283 nm and Ce at 430 nm.
Heterostructures with Strained InGaAs Quantum Wells for RCE Photodiode Applications in the 1.8–2 μm Spectral Range
Authors: Zynek Jadwiga , Jasik Agata , Gaca Jaroslaw , Wojcik Marek , Strupinski Wlodzimierz , Rutkowski Jaroslaw , Wnuk Artur , Klima Krzysztof 
Published: April 2011

ABSTRACTThe results of the work on the technology and characterization methods of resonant cavity enhanced (RCE) photodiode heterostructures with strained InxGa1–xAs quantum wells (0.65≤x≤0.82), designed for the 1.8 - 2 μm spectral range, are presented. The heterostructures grown on InP by metalorganic chemical vapor deposition have been investigated by high-resolution X-ray diffraction with synchrotron source, transmission electron microscopy, photoluminescence and reflectivity spectra measurements. Non-resonant photodiodes fabricated from these epitaxial structures exhibit dark current densities below 10-6 A/cm2 and quantum efficiencies above 1 % (even without bias). These quantum efficiency values are a good basis for the resonant cavity enhancement. The optical field enhancement at quantum wells has been examined in resonant heterostructures before processing.
Electronic and Optical Properties of SiGe alloys within first-principles schemes
Authors: Cappellini G. , Satta G. , Palummo M. , Onida G. 
Published: April 2011

ABSTRACTWe present first-principles calculated electronic and optical properties of some SiGe alloys. The ground-state, electronic excitations and optical properties have been calculated with Ge and Si atoms arranged in different ways among the sites of a diamond-type lattice. For the ground state a DFT-LDA scheme and for the electronic excitations a DFT-GW approach have been respectively used. For the optical properties the DFT-LDA-RPA scheme has been applied for alloys going in composition from Si(100%) to Ge(100%): obtained results have been compared with existing experimental and theoretical data. For the noticeable Si(50%)Ge(50%) alloy also two-particle effects have been evaluated using the Bethe-Salpeter equation.
Novel Noncontact Thickness Metrology for Partially Transparent and Nontransparent Wafers for Backend Semiconductor Manufacturing
Authors: Walecki Wojciech J. , Souchkov Vitali , Lai Kevin , Van Phuc , Santos Manuel , Pravdivtsev Alexander , Lau S. H. , Koo Ann 
Published: April 2011

ABSTRACTSingle probe infrared low coherence optical interferometry has been proven to be an effective tool for characterization of thin and ultra-thin semiconductor Si and compound materials wafers. Its application was however limited to wafers transparent at probing wavelength, and having relatively smooth surfaces. Purpose of this paper is to present an extension of low coherence interferometry to characterization of non-transparent wafers, and wafers with rough surfaces.
Dielectric Properties of Semiconductors by TDDFT in Real-Space and Real-Time Approach
Authors: Zempo Yasunari , Akino Nobuhiko 
Published: April 2011

ABSTRACTThe dielectric responses of semiconductors such as C, Ge, Si, and AlGaAs are studied by the time-dependent density-functional theory. In our study, the real-space grid representation of the electron wave functions is used and the real-time approach is employed for the dynamics of the system. Both the static and dynamic dielectric functions are calculated, and we yielded that the static dielectric constants ε(0) are especially in good agreement with the experimental values. The effect of Al-component in the compound semiconductor AlxGa1−xAs is also studied. The peaks of the imaginary part of the dielectric function change with the band separation as a function of the Al-component. Furthermore, the static dielectric constants show the expected change due to the band separation as a function of the Al-component.
Fabrication of Silicon Nitride Film using Pure Nitrogen Plasma Generated near Atmospheric Pressure for III-V Semiconductor Fabrication
Authors: Hayakawa R. , Yoshimura T. , Nakae M. , Uehara T. , Ashida A. , Fujimura N. 
Published: April 2011

ABSTRACTStable discharging of pure nitrogen can be maintained even at atmospheric pressure when alternative pulsed voltage is applied between two parallel plate electrodes. From optical emission spectroscopy, strong emissions from the N2 2nd positive system, weak emissions from N2 Herman's infrared system and N2 1st positive system were observed. The emission intensities from the N2 2nd positive system and the N2 Herman's infrared system increase with increasing the nitrogen gas pressure, whereas the emission intensities from the N2+ 1st negative system and N2 1st positive system decrease. The thickness of the silicon nitride film fabricated at 500 Torr was 1.6 nm at a nitridation temperature as low as 25°C, regardless of the nitridation temperature and nitridation time. From these results, we conclude that N2(C3IIu) plays an important role for the excellent reactivity of the nitrogen plasma generated near atmospheric pressure.
Electroluminescence from GalnN Quantum Wells Grown on Non-(0001) Facets of Selectively Grown GaN Stripes
Authors: Neubert Barbara , Habel Frank , Bruckner Peter , Scholz Ferdinand , Riemann Till , Christen Jürgen 
Published: April 2011

ABSTRACTNon (0001) GalnN QWs have been grown by low pressure MOVPE on side facets of triangular shaped selectively grown GaN stripes. By analysing low temperature photo- and cathodoluminescence and room temperature electroluminescence, we found strong indications, that both, In and Mg are less efficiently incorporated on these side facets compared to the common (0001) plane with even lower efficiency for stripes running along (1–100) compared to (11–20). Nevertheless, we observed strong light emission from these quantum wells, supposed to be at least partly caused by the reduced piezo-electric field.
Comparative Study of GaN Based Light Emitting Devices Grown on Sapphire and GaN Substrates
Authors: Figge Stephan , Dennemarck Jens , Alexe Gabriela , Hommel Detlef 
Published: April 2011

ABSTRACTThe homoeptaxial growth of GaN based devices has advantages against the heteroepi-taxial realization on substrates such as sapphire or SiC, since heteroepitaxy implies a lot of problems like lattice mismatch, different thermal expansion coefficients, and needs an extensive optimization of the growth at the heterointerface. In this paper we will discuss GaN based light emitting devices grown by homoepitaxy in comparison to devices grown on sapphire. We will show the differences in device performance, device processing and the influence of the thermal resistivity on the devices.
Resonant-Raman Scattering of ZnO Crystallites: the Quasi Nature of the LO Mode
Authors: Chen Xiang-Bai , Morrison John L. , Huso Jesse , Metzger Jonathan G. , Bergman Leah , Efrima Shlomo 
Published: April 2011

ABSTRACTThe Raman modes of ZnO crystallites of the wurtzite structure were investigated via micro-Raman scattering at resonant and out-of-resonant conditions. The E2 mode was the predominant mode in the spectra for out-of-resonant conditions. For the resonant conditions one mode at the spectral range of the LO's of ZnO single crystal was the predominant mode: its frequency was found to be at ∼ 580 cm−1. The A1(LO) and the E1(LO) modes of a reference ZnO single crystal were found to be 568 cm−1 and 586 cm−1 respectively. Two possible mechanisms were considered that may explain the mode frequency of the crystallites: it can be regarded as a confined E1(LO) mode or as a quasi-LO mode. The UV-photoluminescence of the crystallites was found to have the same energy as that of the single crystal ∼ 3.3 eV, indicating the lack of size-confinement of the electronic states in the crystallites, and inter alia that of the phonon states. Our analysis indicated that the observed frequency can be explained in terms of Loudon's model of a quasi-mode behavior which is due to the crystallites tilt.