In this paper, we investigate the method of fundamental solutions (MFS) for solving exterior Helmholtz problems with high wave-number in axisymmetric domains. Since the coefficient matrix in the linear system resulting from the MFS approximation has a block circulant structure, it can be solved by the matrix decomposition algorithm and fast Fourier transform for the fast computation of large-scale problems and meanwhile saving computer memory space. Several numerical examples are provided to demonstrate its applicability and efficacy in two and three dimensional domains.

InTaO4 is an efficient visible-light photocatalyst, which used to be synthesized by solid-state fusion at over 1100 °C. However, irregular morphology and severe agglomeration of particles were acquired due to nonuniform fusion of solid precursors. In this study, InTaO4 was synthesized by two sol-gel routes, the thermal hydrolysis and esterification methods. The precursors were indium (III) nitrate pentahydrate [In(NO3)3] and tantalum(V) butoxide [Ta(OC4H9)5] dissolved in solutions. The InTaO4 powders with a uniform grain size of 17.7 nm were successfully synthesized using the esterification method at a calcination temperature of 950 °C. A uniform InTaO4 thin film nearly 40 nm thick formed on an optical fiber at 1100 °C using the sol prepared by the esterification method. For the first time, InTaO4 was evaluated by the photocatalytic activity of CO2 photo reduction, which was conducted in aqueous solution under visible light irradiation. Cocatalyst NiO was loaded on the surface of InTaO4 to further enhance the methanol yield. The methanol yields of NiO/InTaO4 by esterification method were significantly higher than those by solid-state fusion. The esterification method provided homogeneous mixing of Ta(OC4H9)5 and In(NO3)3, resulting in nano-sized InTaO4 with uniform crystallinity and superior photocatalytic activity.

Erbium and silicon were dual implanted into thermally grown SiO2 film on Si (110) substrates, followed by thermal treatment at 700–1200 °C for 30 min. The microstructure was studied by transmission electron microscope and x-ray diffraction. When the implanted films were annealed at T > 900 °C, the silicon nanocrystals (nc-Si) enwrapped by amorphous silicon (a-Si) could be observed. The thermal quenching behavior at λ = 1.535 μm and its relation with the annealling temperature were also investigated. With increasing annealing temperature, the portion of a-Si and the thermal quenching both decreased. Efficient luminescence from Er ions and weak intensity thermal quenching were obtained from the sample annealed at 1100 °C. The role of a-Si in non-radiative processes at T > 100 K is discussed.

We present a data fusion control scheme for the hand-held camera of the SCORBOT-ER VII robot arm for learning visual tracking and interception. The control scheme consists of two modules: The first one generates candidate actions to drive the end-effector as accurate as possible directly above a moving target, so that the second module can handily take over to intercept it. The desired camera-joint coordinate mappings are generalized by Elman neural networks for a tracking module. The intercept module then determines a suitable intercept trajectory for the robot within the required conditions. The simulation results support the claim that it could be successfully applied to track and intercept a moving target.

It is shown that when the thermodynamic fluxes are included as independent thermodynamic state variables of the generalized entropy density, the constitutive equations for the conserved state variables and the evolution equations for the nonconserved state variables of elastic type-II superconductors can be derived systematically. In particular, the transport equations generalizing the Fourier law for heat transport and the time-dependent Ginzburg-Landau equation for the relaxation of superelectron are proposed in this paper.

Tribochemical studies of the effect of lubricant bonding on the tribology of the head/disk interface (HDI) were conducted using hydrogenated (CHx) carbon disk samples coated with perfluoropolyether ZDOL lubricant. The studies involved drag tests with uncoated and carbon-coated A1203-TiC sliders and also thermal desorption experiments in an ultra-high vacuum (UHV) tribochamber. We observed that a larger mobile lubricant portion significantly enhances the wear durability of the (head/disk interface) HDI by providing a reservoir to constantly replenish the lubricant displaced in the wear track during drag tests. In the thermal desorption tests we observed two distinct temperatures of desorption. The mobile ZDOL layer is desorbed at the lower thermal desorption temperature and the residual bonded ZDOL layer is desorbed at the higher thermal desorption temperature. We also observed that the hydrogen evolution from CHx overcoats initiates lubricant catalytic decomposition with uncoated A1203/TiC sliders, forming CF3 (69) and C2F5(119). The generation of Hydroflouric acid (HF) during thermal desorption experiments provides the formation mechanism of Lewis acid, which is the necessary component for catalytic reaction causing Z-DOL lube degradation

In this work, power and reliability performance of pseudomorphic AIGaAs/InGaAs HEMT's are investigated by 2-D device simulation, spatially-resolved electro-luminescence, light emission spectra analysis, and gate current instabilities. A two-dimensional device simulation was used to exploit the off/on state breakdown origins in the power PHEMT's and to explore the physical mechanisms responsible for light emission in both conditions. A correlation between simulated results and light emission spectra highlights the breakdown origins in PHEMT's.

PHEMT's subjected to off-state breakdown stress and on-state hot carrier stress show changes in device characteristics. While gate leakage current, i.e. a surface leakage component associated with the surface passivation layer is reduced by these stresses, a reduction in drain current, transconductance degradation, and an increase in the impact ionization generated gate current are also observed.

Further improvement in off/on state breakdown voltages and device reliability calls for device structure optimization for lower electric field design, surface passivation treatment for lower surface leakage current, and Schottky barrier enhancement for lower gate current.

The composition and chemistry of the near-surface region of BaTiO3 have been studied using x-ray photoelectron spectroscopy (XPS). It is found that the Ba3d photoclectron peak shows two chemical states, one of which is attributed to the bulk perovskite and the other to a special surface state unrelated to contamination. The bulk component is reduced and the surface component increases when the material is annealed at high temperatures (either in reducing or oxidizing atmosphere). Both the components are unaltered if the sample is exposed to air, solvents, or water: processes that lead to adsorption of impurities. The surface peak, therefore, attributed to a relaxation related and not contamination-related state, has been compared with those in other Ba-containing oxides. The oxygen photoelectron peak consists of a normal perovskite peak typical of most titanates and a higher energy component clearly related to surface contamination. Annealing in reducing atmosphere results in drastically different optical and electrical properties, and in chemical reduction of some Ti4+ ions to Ti3+. The overall stoichiometry, however, does not change with annealing atmosphere. These results have been discussed in light of our current understanding of this and other related oxides.

Metastable face—centered cubic (fcc) Co was grown epitaxially on (111)Si with an intermediate Cu layer in an ultrahigh vacuum chamber at room temperature. The metastable fcc—Co was grown to extend to a thickness of 30 nm. Polycrystalline and epitaxial hexagonal close—packed (hcp) Co was grown on (111)Si without and with 3 nm or thicker intermediate Cu layer, respectively. The key to the successful growth of fcc—Co is to deposit Co directly onto a thin (2 nm or thinner) interface compound (—Cu, which is of hcp structure and consisting of 11.2 to 14.0 at.% Si. The growth of the metastable phase is attributed to the attainment of an appropriate electron/atomratio at the interface to favor the formation of the fcc—Co.

In a Mixed-Signal IC, both digital and analog circuits exist on the same chip. Analog circuit blocks require technology attributes like precise device matching, low parametric drifts and low noise. These requirements raise additional reliability issues, over and above the reliability concerns associated with digital circuits. CMOS device reliability for mixed-signal technologies can be enhanced by modifying device architecture and improving gate oxide integrity. Interconnect metallurgy plays an important role in determining electromigration related contact/via resistance change which may impact matching of devices and resistor pairs. Appropriate source/drain engineering, device design and utilizing nitrided gate oxide has been shown to produce extremely stable devices. This article will cover process architecture and material issues related with device stability and interconnect metallurgy issues related with contact/via stability, especially with W-Plugs.

The formation of amorphous interlayers (a–interlayers) by solid–state diffusion in ultrahigh vacuum deposited polycrystalline Ti thin film on germanium and Sil-xGex alloys grown on (001)Si has been investigated by transmission electron microscopy and Auger electron spectroscopy.

Amorphous interlayers, less than 2 nm in thickness, were observed to form in all as–deposited samples. The growth of a–interlayers was found to vary non–monotonically with the composition of Si–Ge alloys in annealed samples. On the other hand, the formation temperature of crystalline phase was found to decrease with the Ge content. The results are compared with that of the Ti/Si system. The formation mechanism are discussed in terms of thermodynamic and kinetic factors.

We have studied the influence of ion bombardment on the surfaces of MgO and Al2O3 single crystals. The two oxides were sputtered with low energy Ar+ ions, and x-ray photoelectron spectroscopy was used to analyze surface compositions and chemical interactions with metallic adsorbates. Expected changes in surface compositions have been calculated mathematically using first principle formulation from existing literature. The resulting effects on XPS spectra have been predicted based on concentration profile models and agree with experimental observations. Changes in surface oxygen activity were studied by evaporating Ni on these surfaces at an extremely slow rate and analyzing what fraction of the first monolayer was oxidized on adsorption. This fraction, used as a measure of surface oxygen activity, was substantially reduced in Al2O3 on sputtering, but remained practically unchanged for MgO. The amount of these changes matches reasonably well with calculated changes in surface oxygen fraction. Based on these results, the relation between ion bombardment and interfacial bonding has been discussed.

Tantalum nitride, Ta-Si-N, and tantalum silicide films were investigated for use as a diffusion barrier in Al/Si metallization. The former two films were deposited by reactive sputtering of a Ta or TaSi2 target in Ar/N2 gas mixture. The TaSix films were fabricated by sputtering of TaSi2 target. Then, the Ta-Si-N and TaSix film were annealed at temperature 950°C for 15 seconds by RTA. The resistivities of Ta-Si-N, TaN, and TaSix films are about 180, 250, and 60 µohm-cm, respectively. The X-ray photoelectron spectroscopies were made to study the chemical structure of the films. For both nitrides, TaO comprises the native oxide formed at room temperature. A large amount of silicon nitride was formed on the surface of TaSix film during the RTA. Rutherford backscattering and Auger profile were performed to understand the degradation. It was found that these three films are effective diffusion barriers at temperature 620°C.

Epitaxial NiSi2 of single orientation was grown on laterally confined (111)Si. Striking oxide opening size effects on the growth of NiSi2 epitaxy were observed. The formation temperature of NiSi2 on (111)Si was found to be as low as 550°C inside oxide openings 1.8 μm or smaller in size. Epitaxial NiSi2 of single orientation which is identical to that of (111)Si substrate was formed inside oxide openings of or smaller than 1.8, 1, and 0.8 μm in size in samples annealed at 550-750, 800, and 850-900°C, respectively. Preliminary results on the epitaxial growth of CoSi2 are also reported.