bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photoluminescence and Bandgap Narrowing in Heavily Doped n-GaAs
Authors: Yao H.D. , Compaan A. 
Published: March 2011

AbstractExtremely heavily doped n-GaAs was produced by pulsed-laser annealing of Si implanted GaAs, achieving carrier concentrations exceeding 3.2×1019/cm3. Our photoluminescence (PL) spectra indicate a bandgap narrowing due to heavy n-type doping with a functional form of Δεg(eV) = - 6.3 × 10cm-8[(cm-2)]1/3 . At the highest carrier concentration, the bandgap shrinkage reaches -200 meV and the electron Fermi energy is -410 meV. These large values indicate that there exists a considerable conduction band “stretch” between the Γ and L-valley of GaAs for very high n-type concentrations.
Electronic Structure of Li-Impurities in ZnSe.
Authors: Oguchi T. , Sasaki T. , Katayama-Yoshida H. 
Published: March 2011

AbstractElectronic properties of ZnSe with a Li impurity are investigated with use of the local-density-functional approach. The electronic structures are calculated for different impurity sites by taking the neighboring lattice relaxation into account. By comparing their total energies, the stability of the Li impurity in ZnSe is discussed. It is proposed that the Li impurity at the substitutional Zn site might be unstable to the tetrahedral interstitial site with an ionization of Li and a vacancy at the Zn site.
The Symmetry of the EL2 Defect in GaAs
Authors: Trautman P. , Baranowski J.M. 
Published: March 2011

AbstractLinear dichroism has been measured in the broad absorption band of the EL2 defect in GaAs under uniaxial stress. In addition, the splittings of the EL2 zero phonon line (ZPL) at 8378 cm-1 under uniaxial stress applied along [100], [111], and [110] directions have been measured. Splitting of the ZPL under [100] stress is over one order of magnitude smaller than under [111] stress, on the other hand, the linear dichroism in the broad absorption band is roughly equal for these two directions of stress. This is an evidence for the quenching of the coupling to tetragonal strains due to interaction with trigonal modes of the lattice (the Ham effect). Therefore, it is established, that the excited T2 state of EL2 is a localized state subject to dynamical Jahn-Teller coupling to trigonal modes of the lattice. The possibility that the excited T2 state has hydrogenic nature associated with the L minima is ruled out by the present results. The observed splittings of the ZPL together with polarization selection rules clearly indicate the tetrahedral Td symmetry of the EL2 defect ruling out any other point group in particular trigonal C3v In view of the presented experimental results, their interpretation, and recent theoretical investigations, the isolated arsenic antisite AsGa most successfully accounts for the properties of the neutral charge state of the EL2 defect.
Recovery from the Metastable EL2 Defect in GaAs Under Monochromatic Light Illumination.
Authors: Manasreh M. O. , Fischer D. W. 
Published: March 2011

AbstractThe infrared absorption technique is used to study the recovery of the EL2 metastable state in semi-insulating GaAs under monochromatic light illumination. The induced optical recovery is monitored after low intensity (≤ 2mW/cm2) irradiation in the energy range 0.7 ≤ hv ≤ 1.5 eV. The data exhibit a complex structure consisting of a broad band around 0.9 eV and a set of multiple sharp peaks between 1.44 and 1.5 eV. This recovery is strongly dependent on the sample, temperature and illumination time. The present results suggest that a) the existing data and theoretical predictions for the isolated AsGa antisite structure are not compatable with the optical recovery data, b) EL2 is affected dramatically by other defects (traps) present in the sample and c) the peaks observed in the optical recovery data are coincident with the arsenic vacancy energy levels and therefore the present results support the proposed complex models involving an arsenic vacancy.
Acceptor Delta-Doping in GaAs
Authors: Hobson W. S. , Pearton S. J. , Abernathy C. R. , Cabaniss G. 
Published: March 2011

AbstractWe have investigated the formation and diffusion of delta-doped layers in GaAs employing the acceptors Zn, Cd, and C. Organometallic Vapor Phase Epitaxy was used for the growth of the Zn and Cd δ-doped layers while Metalorganic Molecular Beam Epitaxy was utilized to achieve C δ-doping. The narrowest atomic profiles for Zn had full width at half maxima of 80 Å for peak Zn concentrations of ≤ 3 × 1018 cm-3, as measured by SIMS. An effective diffusion coefficient of ≤ 7 × 1017 cm2/s is estimated for a growth temperature of 625°C, based on multiple Zn δ-doped layers. For carbon, a doping spike of 7 × 1019cm-3 with a full width at half maximum of 50Å, as measured by electrochemical capacitance voltage profiling, was achieved and represents the highest doping level yet reported for planar doping. By contrast, it was difficult to achieve doping levels ≥ 4 × 1017 cm-3 for Cd due to its high vapor pressure.
Precipitation Phenomena Associated with Ultra-High Be Doping in Ga0.47In0.53P Layers grown by MBE
Authors: Cotell C.M. , Panish M.B. , Hamm R.A. , Hopkins L.C. , Gibson J.M. 
Published: March 2011

AbstractUltra-high Be doping of Ga0.47In0.53 As layers grown by gas source molecular beam epitaxy has shown that for each growth temperature, there exists a maximum hole concentration (≥1×1020cm-3). Increasing the Be flux above that which produces the maximum hole concentration results in a degradation of the crystalline quality of the films. The degradation of film quality results from precipitation of a Be-rich phase on the surface during growth and nucleation of dislocations at each precipitate. Below that concentration, some of the Be segregates and floats on the growing surface.
Carbon Doping in InGaAs grown by MBE
Authors: Ito Hiroshi , Ishibashi Tadao 
Published: March 2011

AbstractCarbon doping in InxGa1-xAs is investigated using solid source MBE. InAs mole fractions, x, from 0 to 1 are tested. Under a constant doping level, hole concentration decreases with increasing x. When x is higher than 0.6, the conduction type is n and electron concentration increases with x. The conduction-type inversion and the behavior of carrier mobilities are explained by a self-compensation mechanism.
Comparison of Ordered and Modulated Structures in InGaP Alloy Semiconductors grown by MOCVD, Chloride-Vpe and LPE Methods
Authors: Ueda O , Kato T. , Matsumoto T. , Hoshino M. , Takechi M. , Ozeki M. 
Published: March 2011

AbstractOrdered and modulated structures in InGaP alloy semiconductors grown on (001) GaAs substrates by metalorganic chemical vapor deposition, chloride-vapor phase epitaxy, and liquid phase epitaxy have been systematically studied by transmission electron microscopy. In InGaP grown by metalorganic chemical vapor deposition at 630°C, strong ordering of CuPt-type has been observed, which is associated with an abnormality in the photoluminescence peak energy. For crystals grown by chloride-vapor phase epitaxy, CuPt-type ordered structures have also been observed. However, the degree of ordering is weaker in the latter case and crystals grown at 576-740°C exhibit normal photoluminescence peak energies. On the other hand, in crystals grown by liquid phase epitaxy, no superstructure spots are found in the electron diffraction patterns and the crystals exhibit normal photoluminescence peak energies. Modulated structures do not depend on the growth method since they are observed in all crystals. From these results, it has been concluded that the ordered structures are not generated under thermal equilibrium conditions but rather by the diffusion and reconstruction of deposited atoms on the growth surface.
Oxygen and Iron Redistribution upon Thermal Treatment in Iron Implanted Silicon
Authors: Pivac B. , Borghesi A. , Ottolini L. , Geddo M. , Piaggi A. , Stella A. 
Published: March 2011

AbstractIn order to study the iron-oxygen interaction and their redistribution in silicon, different doses of 100 keV iron ions have been implanted into CZ silicon substrates, and subsequently annealed. The redistribution of iron and oxygen upon thermal treatment in nitrogen atmosphere was monitored with SIMS and FTIR measurements. A significant gettering of iron as well as of oxygen into the layer close to the implanted surface has been found only for doses exceeding the critical fluence, therefore indicating that the structural disorder and associated lattice strain field are the main driving forces for gettering mechanism. It has been found, however, that for doses above the critical fluence not all iron ions have been trapped into the damaged region, but a significant part of them have diffused into the bulk of the material, unaffected by gettered oxygen.
Molecular Dynamics studies of Dislocations in SI
Authors: Duesbery M.S. , Michel D.J. , Joos B. 
Published: March 2011

AbstractThe mobility of dislocations in a model Silicon lattice is examined at an atomistic level using molecular dynamics. Straight and double-kinked 30° and 90° partial dislocation glide-set dipoles are modelled in a strain-free environment: reconstruction and antiphase defects are found to be present for 30° partial dislocations. The effects of applied shear strains and of temperatures up to the melting point are considered.
A Tem Investigation of Secondary Dislocations in Grain Boundaries in Germanium
Authors: Griss M. , Seibt M. , Möller H.J. 
Published: March 2011

AbstractGermanium bicrystals containing dissociated low energy grain boundaries with a common [011] tilt axis were studied. The dislocation structure of a grain boundary with a misorientation of about 28° has been investigated in detail and could be interpreted as a near-coincidence Σ 27 - tilt grain boundary. Both conventional and high-resolution techniques were applied to analyze the Burgers vectors of the secondary dislocation network. In all cases non - primitive Burgers vectors were observed. The comparison with previous results indicates that the Burgers vectors of the dislocation network may depend on the degree of misorientation of the bicrystal.
AC Photovoltaic Inspection of P-N Junctions having High Leakage Current
Authors: Honma N. , Shimizu H. , Munakata C. , Ogasawara M. 
Published: March 2011

AbstractA focused photon beam chopped at 2 kHz scans p-n junctions in a p-type Si wafer and ac photovoltages are capacitively measured in order to inspect homogeneities of the junctions. It is found that the ac photovoltages are high not only in the junction areas but also in the field oxide regions around the junctions when the junctions are leaky. This indicates that dense positively charged traps exist at the interface between the heavily boron implanted Si substrate and the field oxide layer around the high leakage junction, and that the traps cause the increase in both the junction leakage current and the ac photovoltage.
Defect Levels in the Near-Surface Region of 2.0 MeV 16O+ Ion Implanted n-GaAs.
Authors: Tin C.C. , Barnes P.A. , Bardin T.T. , Pronko J.G. 
Published: March 2011

AbstractMeV ion implantation in GaAs is known to cause amorphization of the region at the end of the ion range. The near-surface region, however, is still crystalline albeit heavily compensated. We have carried out deep level transient spectroscopy (DLTS) studies of the defect levels in the near—surface region of n—GaAs samples implanted with different doses of 2.0 MeV 16O+ ions.A comparison between the defect structures in the original and the implanted samples shows that implantation produced a broad range of defect levels ranging from 0.58 to 0.3 eV from the conduction band edge. This broad range of defects has an unusually large capture cross—section. The intensities of the DLTS peaks increase with the dose of 160+ ions. The presence of EL2, which was present in the original samples, was not observed in the implanted samples.Results from measurements made on samples that have been implanted at 200°C and on implanted samples subjected to rapid thermal annealing will also be discussed.
Correlation of Void Formation with the Reduction of Carrier Activation and Anomalous Dopant Diffusion in Si-Implanted GaAs
Authors: Ko Kei-Yu , Chen Samuel , Lee S. -Tong , Zheng Longru , Tan T.Y. 
Published: March 2011

AbstractWe report the study of high-dose Si-implanted GaAs containing doses ranging from 1×1014 to 1×1015 cm-2 and with subsequent anneals at 850°C for 1 hour. At doses ≥ 3×1014 cm-2, a severe reduction of carrier concentration and anomalous Si diffusion are observed in the near-surface region. In the same region, small, near-spherical voids are found by transmission electron microscopy. In contrast, for samples implanted with doses ≤ 1×1014 cm-2, voids are not found, and both normal carrier activation and Si diffusion profiles are observed. The concurrent onset of these three phenomena in the same region in high-dose samples leads us to conclude that the severe reduction of carrier concentration and anomalous Si diffusion are attributable to the formation of voids.
Improved Hole Diffusion Lengths in Bulk n-Type GaAs for High Efficiency Solar Cells
Authors: Wong D. , Schlesinger T. E. , Milnes A. G. 
Published: March 2011

AbstractA method for wafer annealing which is effective in suppressing defects and raising minority carrier diffusion lengths in n-type bulk GaAs is described. The beneficial effect of the annealing is shown to be associated with the proximity surface with measurements of photoresponse as a function of depth. The concentration of the hole trap HCX (Ev+0.29eV) varies as a function of depth from the surface, qualitatively, as might be expected of the concentration of the dominant recombination center in the material. The impact of improving the material in this manner on the performance of Zn diffused solar cells is demonstrated.
New Photosensitive Polyimide (SIM2000XL-RTS) for Packaging Applications
Authors: Jeng S. , Xu M. , Liu P. L. , Kwok H. S. , Lee C. J. 
Published: March 2011

AbstractPolyimides are finding increased use as dielectric materials in multi-level metallization technology, which is the key to high-density packaging applications for microelectronics.Newly developed photosensitive polyimidesiloxane (SIM2000XL-RTS) has been evaluated in terms of thermal stability, photosensitivity and lithography as well as dielectric breakdown properties. The sensitivity to N2 laser exposure has been measured under optimized process conditions. We also find that SIM2000XL-RTS can be processed up to 350°C without significant decomposition. Micron-scale contact images can be successfully patterned by both N2 laser and conventional UV lamp exposure. The dielectrical breakdown field strength of SIM2000XL-RTS is about 4 MV/cm by sandwich measurements.
A New Polyimide for Multi-Chip Modules Applications
Authors: Satou Hidetaka , Makino Daisuke , Kikuchi Toru , Saito Takayuki 
Published: March 2011

AbstractCurrently polyimides are used for a multitude of applications in the electronics field. No where else is it's use growing faster than in the multi-chip module market. It's inherent features in process ability, planarity, heat resistance, and patternability make it ideal for production use in multi chip modules.
Adhesion, Reaction and Stability of Metal/Polyimide Interfaces
Authors: Kim J. , Kowalczyk S. P. , Kim Y. H. , Chou N. J. , Oh T. S. 
Published: March 2011

AbstractInterfacial reactions of polyimide with several metals have been investigated by XPS and TEM to determine their effects on adhesion and long term stability. It has been found that the polyimide-on-metal interface and the metal-on-polyimide interface are intrinsically different; in the case of PI-on-metal interface, the precursor of polyimide, polyamic acid, reacts with the metal resulting in a strong chemical bond and therefore, higher adhesion strength than the corresponding metal-on-PI interface. Both interfaces are found susceptible to T/H environment, resulting in significant adhesion loss. The mechanical and electrical properties of polyimide may be altered as a result of the interaction with metals and therefore, great care is necessary to insure a stable interface and the reliability of devices.
Solvent-Induced Damage in Polyimide Thin Films
Authors: Hu M. S. 
Published: March 2011

AbstractSolvent induced damage bands formed in residually strained polyimide thin films on different substrates have been studied. Microscopy studies have shown that these bands resemble crazes. A mechanics approach Is taken to understand the band formation phenomenon.The critical strain for damage formation has been identified. This strain decreases with increase in exposure time, but always exhibits a threshold value. In contrast to the cracking of brittle films, the critical strain has only a weak dependence on the film thickness over a wide range. This behavior obtains because the crazing of the polyimide films is nucleation controlled. Strain-enhanced diffusion of solvent into the films is considered to be responsible for the property degradation that leads to damage formation.
Ion Exchange Reaction in a Thin Film of Polyimide
Authors: Akagi Yoshiro , Ishino Mariko , Okamoto Yasunari , Taniguchi Hiroshi , Ohoka Kohji , Nakajima Yoshiharu 
Published: March 2011

AbstractRelationship between the degree of imide-ring-condensation and the absorbed quantity of sodium ion was studied in a polyimide film of 100nm thick immersed in an alcoholic solvent containing sodium ion in order to elucidate a mechanism of incorporation of ionic species. Absorption and depth-profile of sodium ion in a film were quantitatively determined by chemical analysis and secondary ion mass spectroscopy. Concentration of sodium ion in a thin film by two orders of magnitude was observed, and distribution of sodium ion in a thin film was found to be uniform, which cannot be accounted for by any kinds of previous models based on diffusion, permeation, or solvation. Instead, chemical ion-exchange model is proposed and is found to satisfactorily explain the experimental results.
New Multilayered Materials with Low Dielectric Permittivity for VLSI Applications
Authors: Mehrotra V. , Kwon T. , Giannelis E. P. 
Published: March 2011

AbstractA new generation of substrate materials with low dielectric permittivity have been developed. These new ceramic-based nanocomposites consist of a quasi two-dimensional, multilayered structure realized by the intercalation of molecular species into the galleries of a host lattice. The materials have been characterized by x-ray diffraction, electronic and infrared spectroscopy. The relative permittivities vary between 2.5 and 4 at 1 MHz. The new hybrids can be processed at relatively low temperatures (below 350°C) and allow for step coverage of submicron structures.
Dielectric Properties of Sintered AIN
Authors: Harris R. D. , Enck R. C. , Fields J. L. 
Published: March 2011

AbstractWe have initiated a study of the ac electrical properties (dielectric constant and dielectric loss) and the dc resistivity of sintered AIN. For this study, we have used samples purchased commercially as well as samples made by the Carborundum Company, a member of the BP Group. Variations are observed in the room temperature dielectric constant for AIN substrates obtained from different sources. The source-to-source range is from 8.5 to 8.7. This range is lower than the 8.8 to 9.2 that is generally reported in the product literature. Similar source-tosource variations in the room temperature dielectric loss are observed. All of the samples show thermally activated behavior in the dc resistivity. The activation energy observed for all of the samples is similar, EA ∼0.47 eV; however, different pre-exponential factors are apparent. As a result, there are large variations in the measured room temperature resistivities for samples from different sources.
Influence of Firing Gas Pressure on the Microstructure and Thermal Conductivity of ALN Ceramics
Authors: Tsukada M. , Makihara H. , Kamehara N. , Niwa K. 
Published: March 2011

AbstractThe thermal conductivity of aluminum nitride is significantly affected by its purity. We used CaCO3 as an additive to decrease the oxygen content. Calcium-aluminate is formed by the reaction of the aluminum nitride powder oxide layers and CaO during firing. We investigated the influence of firing gas pressure on the microstructure and thermal conductivity of aluminum nitride. The thermal conductivity reached 270 W/m°K when 4 wt% CaO was added and firing gas pressure was 700 kPa. Under these conditions, the amount of remaining oxygen was at its minimum and the grain size of the aluminum nitride was at its maximum.
Planar and Curved Defects in Aluminum Nitride: Their Microstructure and Microchemistry
Authors: Westwood Alistair D. , Notis Michael R. 
Published: March 2011

AbstractThe microstructure and microchemistry of planar and curved defects in Aluminum Nitride (AIN) has been investigated using Conventional Transmission Electron Microscopy (CTEM), Convergent Beam Electron Diffraction (CBED), and Analytical Electron Microscopy (AEM) techniques. Both defect morphologies were identified as Inversion Domain Boundaries (IDB). Microchemical analysis revealed oxygen segregation to the planar faults; when present on the curved defects, oxygen was at a lower concentration than in the planar defect case. Annealing experiments on defect containing AIN support our microchemical analysis of oxygen segregation. A proposed model for the formation of these two types of boundaries is presented.
Inversion Domain Boundaries and Oxygen Accommodation in Aluminum Nitride
Authors: Youngman R. A. , Harris J. H. , Labun P. A. , Graham R. J. , Weiss J. K. 
Published: March 2011

AbstractAluminum nitride is known to have a large affinity for oxygen as an impurity. At high levels (>∼4 wt/o) the oxygen is incorporated in the form of planar stacking faults where “pure” 2H AIN is regularly interspersed with a layer of oxygen at the faults. At oxygen levels lower than ∼ 4 wt/o the structure shows an expanded c-axis. The present authors have not observed this effect, rather a random distribution of stacking faults is observed along with another, more prevalent, extended defect identified as an inversion domain boundary (IDB). The IDBs are significantly aplanar (indicating a low interface energy), and often have precipitates and other, faceted defects associated with them. The role of these defects in oxygen accommodation in AIN has been investigated both structurally and chemically by electron optical methods (SEM, TEM, STEM, HREM, CBED, EDS, EELS, and CL-TEM). The structural nature of the boundaries, in the absence of oxygen, requires Al-Al or N-N bonding to occur with some frequency across the boundary. Such bonding is unlikely due to the excess energy required. Chemical analysis (EELS) and luminescence studies (CL-TEM) reveal that oxygen is often associated with the boundaries and may mediate the bonding at the boundary. A model is proposed for the IDB which includes structural aspects combined with considerations of stoichiometry in an effort to understand the origin and energetics of this defect.
Future Packaging Directions in the 1990's and their Materials Challenges
Authors: Eastman Dean E. 
Published: March 2011

AbstractIn the 1990's, silicon integrated circuit technology will continue to rapidly advance from VLSI towards ULSI. For example, 64 × 106 circuit microprocessor chips, 106 gate CMOS logic chips, and 105 circuit bipolar logic chips, and beyond, will make up the electronics systems of the 1990's. To support these silicon technology advances in density, performance, and cost reduction, packaging technology will also have to advance rapidly to meet packaged electronics systems requirements. Packaging solutions will be required for machines ranging from supercomputers and mainframes to minis and workstations, and for consumer electronics. Silicon technology advances will continue to enable the unique rates of change in performance, function, and cost per function that characterize the information technology industry, including the computer, communications, and consumer electronics industries.