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Persistent sensorimotor impairments after stroke can negatively impact quality of life. The hippocampus is involved in sensorimotor behavior but has not been widely studied within the context of post-stroke upper limb sensorimotor impairment. The hippocampus is vulnerable to secondary degeneration after stroke, and damage to this region could further weaken sensorimotor circuits, leading to greater chronic sensorimotor impairment. The purpose of this study was to investigate the cross-sectional association between non-lesioned hippocampal volume and upper limb sensorimotor impairment in people with chronic stroke. We hypothesized that smaller ipsilesional hippocampal volumes would be associated with worse upper-limb sensorimotor impairment.Cross-sectional T1-weighted brain MRIs were pooled from 357 participants at the chronic stage after stroke (>180 days post-stroke) compiled from 18 research cohorts worldwide in the ENIGMA Stroke Recovery Working Group (age: median = 61 years, interquartile range = 18, range = 23-93; 135 women and 222 men). Sensorimotor impairment was estimated from the Fugl-Meyer Assessment of Upper Extremity scores. Robust mixed-effects linear models were used to test associations between post-stroke sensorimotor impairment and hippocampal volumes (ipsilesional and contralesional separately; Bonferroni-corrected, p-value < 0.025), controlling for age, sex, lesion volume, and lesioned hemisphere. We also performed an exploratory analysis to test whether sex differences influence the relationship between sensorimotor impairment and hippocampal volume.Upper limb sensorimotor impairment was positively associated with ipsilesional (p = 0.005; d = 0.33) but not contralesional (p = 0.96; d = 0.01) hippocampal volume, such that impairment was worse for participants with smaller ipsilesional hippocampal volume. This association remained significant independent of lesion volume or other covariates (p = 0.001; d = 0.36). Evidence indicates an interaction between sensorimotor impairment and sex for both ipsilesional (p = 0.008; d = −0.29) and contralesional (p = 0.006; d = −0.30) hippocampal volumes, whereby women showed progressively worsening sensorimotor impairment with smaller hippocampal volumes compared to men.The present study has identified a novel association between chronic post-stroke sensorimotor impairment and ipsilesional, but not contralesional, hippocampal volume. This finding was not due to lesion size and may be stronger in women. We also provide supporting evidence that smaller hippocampal volume post-stroke is likely a consequence of ipsilesional damage, which could provide a link between vascular disease and other disorders, such as dementia.

This study was undertaken to determine the glucose, yeast extract, tryptone and Tween 80 concentrations in a cultivation medium for optimal biomass production of a probiotic bacterium, Lactobacillus rhamnosus ATCC 7469. Using response surface methodology, a central composite rotatable design was applied to allocate treatment combinations. A polynomial regression model containing linear, quadratic, cubic and quartic terms was used for analysis of the experimental data. Effects involving all four factors evaluated were found to be significant and the strongest effect was given by tryptone concentration. Estimated optimum conditions of the factors for the growth of L. rhamnosus were as follows: glucose = 4.4% (w/v), yeast extract = 6.0% (w/v), tryptone = 6.0% (w/v) and Tween 80 = 1.1 mL/L. The optimum-point medium gave higher counts of viable cells, specific growth rate and biomass productivity than de Man, Rogosa and Sharpe and the center-point media. Practical Applications With increasing demand for food products containing probiotic microorganisms from health-conscious consumers, there arises a need to establish effective fermentation techniques for probiotic biomass production. Medium formulation, fermentation parameters and fermentor design play important roles to ensure optimal results. This study highlights a statistical approach to optimizing medium formulation for a probiotic lactic acid bacteria strain, which is known for its high nutritional demands. The optimal medium formulation obtained from this study can be used for improving Lactobacillus rhamnosus fermentation as it is capable of producing more viable cells than de Man, Rogosa and Sharpe medium, which is generally recognized and used as a suitable medium for lactic acid bacteria cultivation.

We present results for InP quantum dots (QDs) within a AlGaInP matrix grown by metalorganic vapor phase epitaxy (MOVPE) at an elevated temperatures of 690–730 °C. InP/AlGaInP QD lasers grown under these conditions operate at room temperature in a pulsed mode with a low threshold of 190 A/cm2 (38 A/cm2 per QD sheet) and lasing wavelength of 740 nm for a 2000 μm long device with uncoated facets.

Solid-state reactions between Er and Ge (001) under different processing conditions were investigated. Under normal rapid thermal processing (RTP) in high-purity N2 ambience, the Er–Ge film formation was Fcontaminated_ with Er2O3 even at low temperature annealing. Ti capping of Er films before RTP delayed Er2O3 formation with the Ti cap acting as a sacrificial layer for the Er underneath. Vacuum annealing of Er films significantly reduced Er2O3 formation even after higher temperature annealing. High quality Er–Ge films can thus be formed through solid-state reaction of Er and Ge if oxygen contamination from annealing ambient during RTP is controlled. The Er–Ge phase had low sheet resistance values averaging 3 to 4 V/sq. ErGe1.8 was formed from the solid-state reaction between Er and Ge(001) in vacuum. D 2005 Elsevier B.V. All rights reserved.

We discuss a novel approach to the optimisation of quantum dot bilayer structures grown by molecular beam epitaxy. Use of a kinetic segregation model has shown that a reduction of the In composition for the upper layer of a bilayer structure can be used to compensate for the excess In that exists on the surface prior to growth. Three samples have been grown with upper dot In compositions varying from 90% to 100% and have been investigated by means of optical spectroscopy and electron microscopy.

The use of buried tungsten silicide layers for confinement of terahertz optical modes is described. Silicon-on-silicide substrates are prepared using a bond and etch-back technique, and the successful growth of extremely long (600 period) strain-balanced p-Si/SiGe quantum cascade heterostructures on these substrates is demonstrated. THz electroluminescence is observed from these structures at low temperature, when the structure is biased so as to obtain interwell (‘diagonal’) transitions between heavy and light hole subbands. The emission shows a strong polarisation dependence, indicating the efficacy of the silicide layer in confining long wavelength TM modes.

We address fundamental issues relating to the symmetry of the shape and the nonuniform composition of InGaAs quantum dot islands. Using atomistic simulations in the framework of the Tersoff empirical potential, we study the effect of compositional gradients in the In distribution on the piezoelectric effect in quantum dots. We demonstrate that the internal piezoelectric fields contribute strongly to the experimentally observed optical anisotropies. This is confirmed by accurate high-resolution transmission electron microscopy analysis over hundreds of islands grown in different conditions that reveals the absence of structural anisotropy under our growth conditions.

Asymmetric rolling, in which the circumferential velocities of the upper and lower rolls are different, can give rise to intense plastic shear strains and in turn shear deformation textures through the sheet thickness. The ideal shear deformation texture of fcc metals can be approximated by the // ND and {001} orientations, among which the former improves the deep drawability. The ideal shear deformation texture for bcc metals can be approximated by the Goss {110} and {112} orientations, among which the former improves the magnetic permeability along the directions and is the prime orientation in grain oriented silicon steels. The intense shear strains can result in the grain refinement and hence improve echanical properties. Steel sheets, especially ferritic stainless steel sheets, and luminum alloy sheets may exhibit an undesirable surface roughening known as ridging or roping, when elongated along RD and TD, respectively. The ridging or roping is caused by differently oriented colonies, which are resulted from the oriented columnar structure in ingots or billets, especially for ferritic stainless steels, that is not easily destroyed by the conventional rolling. The breakdown of columnar structure and the grain refinement can be achieved by asymmetric rolling, resulting in a decrease in the ridging problem.

The nature of the few particle wavefunctions for neutral and positively charged excitons is probed in individual InGaAs quantum dots using Stark-effect perturbation spectroscopy. A systematic reduction of the vertical component of the permanent excitonic dipole (pz) is observed as additional holes are added to the dot. A comparison with calculations reveals that this reduction (Δpz/e∼15–20%) is accompanied by a significant lateral expansion of the hole (∼2 nm ) and contraction (∼1 nm ) of the electron wavefunctions. We suggest that this lateral redistribution of the charged exciton wavefunctions provides an optical means to probe the lateral composition profile of the dot.

We demonstrate greatly improved threshold current and modal gain performance of 1.3-/spl mu/m quantum-dot (QD) lasers by growing the GaAs spacer layers in two parts, where subtle modification of the spacer layer growth temperature profoundly influences the QDs. Measurements reveal significantly increased ground state (1.3 /spl mu/m) modal absorption by increasing the growth temperature of the second part of the spacer layer. Improved modal gain is achieved, enabling continuous-wave lasing from a 1-mm-long uncoated laser, even without p-doping. This approach provides a potentially viable route to superior edge-emitting lasers and GaAs-based 1.3-/spl mu/m vertical-cavity surface-emitting lasers.

We have grown InP quantum dots with different rates and on substrates with different orientations. The growth conditions have a major influence on the form of the gain spectrum. Using a high growth rate on a 10 off (100) substrate we obtain a broad gain spectrum due to contributions from a bimodal dot size distribution whereas a sample containing mostly small dots, produced using (211) B substrates, has a narrower gain spectrum centered at a shorter wavelength of ~700-710nm. The modal gain saturates at a magnitude significantly smaller than the modal absorption, nevertheless the measured values of modal gain are sufficient to sustain laser action, and structures grown at high growth rate on 10 off (100) substrates are capable of providing laser devices operating in the region of 750nm.

We present a midinfrared absorption study of an n–i–n structure containing two planes of strongly coupled In0.5Ga0.5As self-assembled quantum dots. We find that the dominant absorption occurs for light polarized in the growth plane (E//xy), contrasting with uncoupled dots which exhibit stronger absorption for light polarized in the growth direction (E//z) in the same energy range. Results from the coupled dot sample indicate that the confinement length in the growth direction is increased, lowering the energy of the s-like ground state and hybridizing px,y-like excited states and wetting layer states. A significantly increased normal incidence photocurrent signal is measured for the sample containing coupled dots, relative to samples containing up to 30 layers of uncoupled dots, confirming the enhancement of the normal incidence absorption.

The Tokamak Physics Experiment (TPX) device, which is under conceptual design in the US, presents several neutronics and shielding issues that are challenging from the design analysis viewpoint. This paper presents an overview of the various issues and a summary of the various design analyses that have been performed thus far to quantify the issues and to guide the design toward near-optimal engineering solutions to the problems. Some planned activities are also discussed.

The authors illustrate the designs of radiation shielding for the TFTR DT diagnostics using the ACX and TVTS systems as specific examples. The main emphasis here is on the radiation transport analyses carried out in support of the designs. Initial results from the DT operation indicate that the diagnostics have been functioning as anticipated and the shielding designs are satisfactory. The experience accumulated in the shielding design for the TFTR DT diagnostics should be useful and applicable to future devices, such as TPX and ITER, where many similar diagnostic systems are expected to be used.

Ta/Cu is a strategic material combination for ultra-large-scale integrated wafer technology. Here we report an unconventional method for the synthesis of a [110]-oriented nanocrystalline α-Ta thin film on freshly prepared Cu(111) templates at

Fe3Si thin films were sputter-deposited on Si(001) substrates. Structural investigations show that Fe3Si was deposited poly-crystalline with a Si-containing layer at the Fe3Si/Si interface. The formation of the layer was attributed to the influence of low deposition rates used in this study on the grain nucleation in Fe3Si. This layer helps to stabilize the ferromagnetic properties of the subsequent annealed films at 350 degrees C with 5 Oe obtained for coercive field H(c), approximately 920 emu/cm3 for saturation magnetization M(s) and approximately 0.9M(s) for remnant magnetization M(r).

The Tokamak Physics Experiment is designed to develop the scientific basis for a compact and continuously operating tokamak fusion reactor. It is based on an emerging class of tokamak operating modes, characterized by beta limits well in excess of the Troyon limit, confinement scaling well in excess of H-mode, and bootstrap current fractions approaching unity. Such modes are attainable through the use of advanced, steady state plasma controls including strong shaping, current profile control, and active particle recycling control. Key design features of the TPX are superconducting toroidal and poloidal field coils; actively-cooled plasma-facing components; a flexible heating and current drive system; and a spacious divertor for flexibility. Substantial deuterium plasma operation is made possible with an in-vessel remote maintenance system, a lowactivation titanium vacuum vessel, and shielding of ex-vessel components. The facility will be constructed as a national project with substantial participation by U.S. industry. Operation will begin with first plasma in the year 2000.

This paper presents some major integration challenges in Ultra low-k (ULK) Back-End-Of-Line (BEOL) interconnects for 45nm and beyond. The discussions mainly address the challenges that arise from ultra violet (UV) curing that cause changes in the composition of Nitrogen doped Silicon Carbide (SiCN), poor mechanical strength of ULK, Reactive Ion Etching (RIE) and barrier deposition plasma induced damage at the sidewall and the bottom of the trench, and gap-fill limitation of the copper (Cu) process. The physical characterization and Resistance-Capacitance (RC) results of the ULK integration are also presented.

In the Compact Ignition Tokamak (CIT), significant nuclear heating results from the neutron and γ interactions in structural components near the plasma and it affects their thermo-mechanical behavi...

This paper reports on accurate determinations of fusion neutron yields on the Tokamak Fusion Test Reactor (TFTR) which require that the neutron detectors be absolutely calibrated in situ, using neutron sources of known strengths. For such calibrations, numerical simulations of neutron transport can be powerful tools in the design of experiments and the study of measurement results. On the TFTR, numerical calibration experiments are frequently used to complement actual detector calibrations. Calculational approaches and transport models used in these numerical simulations are presented and the results from a simulation of the calibration of {sup 235}U fission detectors are summarized.

With appropriate approximations, the delayed gamma dose rate problem can be formulated in terms of the effective delayed gamma production cross section. The coupled neutron-delayed gamma transport equations take the same form as the coupled neutron-prompt gamma transport equations and they can, therefore, be solved directly in the same manner. This eliminates the flux coupling step required in conventional calculations and makes it easier to handle complex, multidimensional problems, especially those that call for Monte Carlo calculations. Mathematical formulation and solution algorithms are derived. The advantages of this method in complex geometry are illustrated by its application in the Monte Carlo solution of a practical design problem.

The lack of a stable native germanium oxide has been the main obstacle for the use of Ge in complementary metal oxide-semiconductor CMOS devices. However, recent development of next generation deposited high-k gate dielectrics for Si also allows for the fabrication of high-performance Ge-based metal-oxide-semiconductor field effect transistors (MOSFETs). For the formation of electrical contacts in Ge-based MOSFETs, transition metal germanides, such as Ni- and Pt-germanides, appear to be suitable candidates for this application due to their low resistivity, low formation temperatures (as low as 250degC), and ability to form in self-alignment. In this work, we have characterized the material and electrical properties of nickel and platinum germanide films as Schottky source/drain contacts for Ge-MOSFETs. This paper will focus on the electrical characterization of Ni- and Pt-germanide Schottky contacts on crystalline germanium substrates with particular emphasis on the theoretical analysis of the effect of inversion layer on I-V and C-V characteristics. In addition, the Schottky barrier modulation by germanidation induced dopant segregation will also be discussed.

The lack of a stable native germanium oxide has been the main obstacle for the use of Ge in complementary metal oxide-semiconductor CMOS devices. However, recent development of next generation deposited high-k gate dielectrics for Si also allows for the fabrication of high performance Ge-based metal-oxide-semiconductor field effect transistors (MOSFETs). For the formation of electrical contacts in Ge-based MOSFETs, transition metal germanides, such as Ni and Pt germanides, appear to be suitable candidates for this application due to their low resistivity, low formation temperatures (as low as 250degC), and ability to form in self-alignment. In this work, we have characterized the material and electrical properties of nickel and platinum germanide films as Schottky source/drain contacts for Ge-MOSFETs. This talk will present and discuss experimental results on Ni- and Pt-germanide phase formation, interfacial/surface morphology and Schottky barrier heights in Ni&Pt-germanide contacts formed by the solid state reaction of Ni/Ge(001) and Pt/Ge(001)

This work demonstrates that there are no fundamental obstacles to the realization of a Si/SiGe quantum cascade laser. This study also reports a number of significant achievements which indicate that the technology is now sufficient, or can be developed to a sufficient level, to attain a working device.

Time-resolved studies of the dynamics of intersubband transitions are reported in three different strain symmetrized p-Si∕SiGe multiple-quantum-well and quantum cascade structures in the far-infrared wavelength range (where the photon energy is less than the optical phonon energy), utilizing the FELIX free-electron laser. The calculated rates for optical and acoustic phonon scattering, alloy disorder scattering, and carrier-carrier scattering have been included in a self-consistent energy balance model of the transient far-infrared intersubband absorption, and show good agreement with our degenerate pump-probe spectroscopy measurements in which, after an initial rise time determined by the resolution of our measurement, we determine decay times ranging from ∼2 to ∼25 ps depending on the design of the structure. In all three samples the lifetimes for the transition from the first light hole subband to the first heavy hole subband are found to be approximately constant in the temperature range 4–100 K.

We probe the permanent excitonic dipole of neutral and positively charged excitons in individual ${\mathrm{In}}_{0.5}{\mathrm{Ga}}_{0.5}\mathrm{As}$ self-assembled quantum dots using Stark effect perturbation spectroscopy. A systematic reduction of the permanent excitonic dipole is found as excess holes are controllably added to individual dots containing a single exciton $({X}^{0})$. Calculations of the few-body states show that this effect arises from a strong, Coulomb-mediated, spatial redistribution of the few-body wave function upon charging. By investigating correlations between the permanent dipole, polarizability, and the emission energy of ${X}^{0}$ for many dots, we also show that the strength of the $\mathrm{In}:\mathrm{Ga}$ composition gradient is related to the absolute In content.

In this paper, we demonstrated electroluminescence in strain-symmetrised structures with up to 600 active periods. The wafer also demonstrates for the first time growth of a strain symmetrised Si/SiGe superlattice on top of a silicon-on-silicide wafer where the silicide is designed to be a bottom reflector in waveguide cavity. TEM images of the structure demonstrated excellent planarity and uniformity of the active periods.

Terahertz electroluminescence due to light hole-heavy hole intersubband transitions in p-type Si/SiGe quantum cascade structures has been observed in both surface-normal and edge emission geometries. THz output powers of up to 50 nW have been observed for surface emission from 100 period Si/sub 0.76/Ge/sub 0.24//Si heterostructures grown on a Si/sub 0.8/Ge/sub 0.2/ relaxed buffer or 'virtual substrate'.

Intersubband electroluminescence results are presented from Si/SiGe quantum cascade emitters at and at temperatures up to . The effect of adding doping into the active quantum wells was studied in addition to reduced barrier widths from previous measurements. While the current through the sample is increased by the addition of doping, the emitted power is reduced through additional free carrier absorption and Coulombic scattering. Free electron laser measurements confirm the intersubband transitions in the quantum wells of the cascade devices and produce non-radiative lifetimes of 20ps between 4 and 150K.

The quantum cascade laser provides one possible method of realizing high efficiency light emission from indirect band gap materials such as silicon. Strain-symmetrized Si/SiGe samples designed to investigate the intersubband properties of quantum wells are examined. Electroluminescence data from Si/SiGe quantum-cascade staircases demonstrating edge emission from heavy-hole to heavy-hole transitions and light-hole to heavy-hole transitions are presented. In surface-normal emission only light-hole to heavy-hole electroluminescence is observed at ( wavelength) as predicted by theory. Modulation-doped SiGe quantum well samples are also investigated to determine the underlying physics in the system. Results of picosecond time resolved studies of the dynamics of the intersubband transitions using a free electron laser are presented which show approximately constant relaxation times of below .

Whilst most present day efforts towards the realisation of a silicon based laser are focused on the near-infrared (telecommunications) wavelengths, one of the most promising technical approaches is that of a silicon-germanium (SiGe) quantum cascade laser (QCL) operating in the far-infrared or terahertz frequency range. Until recently, the terahertz band (1–10 THz) has proved relatively inaccessible for science and engineering applications since it lies above the present upper frequency limit of millimetre wave electronic based oscillators, and below the range of near and mid-infrared solid state lasers and detectors. However, there is currently a great deal of interest in the development of terahertz technology for imaging and sensing applications: terahertz pulsed imaging has been shown to be capable of detecting caries (the precursor of decay) in human teeth [1], and there are also promising signs that the method could be used to detect basal cell carcinoma (a common form of skin cancer) [2]. Many chemical and biological molecules have absorption lines in the THz band, and therefore applications are envisaged in chemical/biological detection and identification. THz imaging is also potentially suitable for baggage/personnel scanning for security applications, where it would provide a low-energy, non-ionising alternative to X-rays.

The quantum cascade laser provides one potential method for the efficient generation of light from indirect materials such as silicon. While to date electroluminescence results from THz Si/SiGe quantum cascade emitters have shown higher output powers than equivalent III–V emitters, the absence of population inversion within these structures has undermined their potential use for the creation of a laser. Electroluminescence results from Si/SiGe quantum cascade emitters are presented demonstrating intersubband emission from heavy to light holes interwell (diagonal) transitions between 1.2 THz (250 μm) and 1.9 THz (156 μm). Theoretical modeling of the transitions suggests the existence of population inversion within the system.

Terahertz (far-infrared) intersubband electroluminescence is reported in p-type Si/SiGe quantum wells and quantum cascade structures. Surface-normal emission (without the aid of a surface grating) from light hole - heavy hole intersubband transitions has been observed for the first time in a quantum cascade device. Edge-emission measurements have also been performed, which show emission from both heavy hole - heavy hole and light hole - heavy hole transitions, and have allowed demonstration of the polarisation dependence of the emitted power, according to the selection rules for the intersubband interactions. The electroluminescence is visible up to temperatures of ~150K, in the multiple quantum well structures, and >=77K in the quantum cascade structure.

Heterojunction solar cells with Al-alloyed polycrystalline p-type β-phase iron disilicide [p-β-FeSi2(Al)] on n-Si(100) were investigated. The p-β-FeSi2(Al) was grown by sputter deposition and rapid-thermal annealing. Photocurrent of ∼1.8 mA/cm2 and open-circuit voltage of ∼63 mV were obtained for p-β-FeSi2(Al)/n-Si(100)/Ti/Al control cells with indium-tin-oxide (ITO) top electrode. Open-circuit voltage increased considerably once thin Al layer was deposited before amorphous-FeSi2(Al) deposition. Furthermore, device performances were found to improve significantly (∼5.3 mA/cm2 and ∼450 mV) by introducing germanium-nitride electron-blocking layer between ITO and p-β-FeSi2(Al). The improvement is attributed to the formation of epitaxial Al-containing p+-Si at p-β-FeSi2(Al)/n-Si(100) interface and suppressed back-diffusion of photogenerated electrons into ITO.

We show that the polarization of the emission of a single quantum dot embedded within a microcavity pillar of elliptical cross section can be completely controlled and even switched between two orthogonal linear polarizations by changing the coupling of the dot emission with the polarized photonic modes. We also measure the spatial profile of the emission of a series of pillars with different ellipticities and show that the results can be well described by simple theoretical modeling of the modes of an infinite length elliptical cylinder.

The excitation power dependence of the ground and excited state transitions in type-II InAs-GaAs0.78Sb0.22 quantum dot structure has been studied. Both transitions exhibit a strong blueshift with increasing excitation power but their separation remains constant. This behavior indicates a carrier-induced electric field oriented predominantly along the growth axis, which requires the holes to be localized in the GaAsSb above quantum dots. An accelerated blueshift of the ground state emission is observed once the excited state in the dots starts to populate. This behavior can be explained by a smaller spontaneous recombination coefficient for the excited state transition.

Electromigration in 0.07 μm wide Cu interconnections has been investigated for sample temperatures from 213 to 300°C. The effect of atomic-layer- or physical-vapor-deposited TaN x and physical-vapor-deposited Ta liner layers in Cu damascene lines on electromigration was also studied. A lower lifetime and activation energy for electromigration was observed in tested lines with sidewall voids. Similar electromigration lifetime and activation energy observed from samples with either atomic-layer- or physical-vapor-deposited TaN, suggested that the dominant diffusion paths in the Cu lines were not sensitive to the TaN x layer and were along the Cu/dielectric interface and/or grain boundaries.

The phase and texture of of Er-germanide formed on Ge(001) through a solid-state reaction between Er thin films and Ge(001) via rapid thermal annealing (300-600°C) were investigated. It was found that amorphous ErGe 1.2 forms at 300°C, followed by the formation of AlB 2 hexagonal ErGe 1.5 at 400-500°C and then orthorhombic ErGe 1.8 at 600°C. X-ray diffraction pole figure measurement revealed that the ErGe 1.5 5 films formed at 400-500°C consist predominantly of epitaxial grains with an orientation relationship of ErGe 1.5 (1100)[0001]//Ge(001)[011], although the presence of a considerable amount of epitaxial grains with an orientation relationship of ErGe 1.5 (1012)[0110]//Ge(001)[010] was also observed in the film formed at 400°C. The germanide film formed at 600°C was found to consist of randomly orientated orthorhombic ErGe 1.8 grains. Among the three different germanide phases, ErGe 1.5 showed minimum resistivity values as low as ∼ 19 μΩ cm.

We have investigated the effects of growth temperature on the properties of 1.6μm GaInNAs∕GaAs multilayer quantum wells (MQWs). Strong room-temperature optical efficiency is obtained at 1.58μm for the sample grown at 375°C. However, the photoluminescence intensities with emission at similar wavelength are dramatically degraded for the samples grown at 350 and 400°C. Structural investigations show that compositional modulation and defects occurred in the sample grown at 400°C and possible point defects within the MQWs grown at 350°C. Based on these observations, the mechanism of effects of growth temperature on near-1.55-μm GaInNAs∕GaAs MQWs is discussed.

Different processes, including cool physical vapor deposition (PVD), of Ta barrier and Cu seed deposition were compared in Cu interconnect development. In the cool Ta process, the substrate temperature was 100°C in the standard process. With the cool process, via resistance (0.19 μm in via size) was reduced by about 25%, although 40% thicker Ta was measured at the via bottom. This was not in agreement with the common understanding that the thicker the Ta film is, the higher the via resistance. Blank film studies suggested that a mixed texture of α- and β-Ta was formed at via bottom in the new Ta/Cu process. X-ray diffraction spectra clearly exhibited the existence of α-Ta in addition to the β-Ta, where the latter is usually observed in the standard process. Electron diffraction spectra further supported the claim of mixed α-/β-Ta formation at via bottom. Moreover, Rutherford backscattering data suggested that the mixed α-/β-Ta had even higher thermal stability.

Several modifications to existing escaping alpha scintillation detectors in TFTR will be needed before they could be used on ignited tokamaks such as CIT or ITER. The main difficulties are the large heat flux at the desired detector locations and the accumulated radiation damage to the scintillator itself. Constraints imposed by these problems can probably be overcome by using remotely movable (and removable) detectors.