The optical and electrical properties of “tilted” and “spiral” indium tin oxide (ITO) thin films are reported. The influence of the flux incident angle on the optical and electrical properties is investigated. When the flux incident angle is increased, both the refractive index and extinction coefficient of the film are decreased, but the resistivity is increased. Thus, the physical properties of the film can be modified over a wide range by adjusting the flux incident angle and substrate rotation scheme. It is suggested that the oblique angle deposition technique provides ITO films with more application possibilities by allowing their optical and electrical properties to be tailored.

The correlation among apparent global plasticity, Poisson’s ratio, and fragility in monolithic bulk metallic glass (BMG) alloys has been investigated in the present study. The shear and bulk moduli in monolithic Cu-based BMG alloys have been measured by resonant ultrasound spectroscopy (RUS) and ultrasonic technique. The Cu43Zr43Al7Ag7 BMG alloy showing a large apparent global plasticity (∼8%) exhibits a high Poisson’s ratio when compared with that of Cu43Zr43Al7Be7 BMG alloy. In addition, the fragility of Cu-based BMG alloys can be obtained by differential scanning calorimetry (DSC). The fragility index m of Cu43Zr43Al7Ag7 BMG alloy is slightly larger than that of Cu43Zr43Al7Be7 BMG alloy. The correlation between Poisson’s ratio and fragility in BMG alloys can be presented by a simple relation of m − 17 = 14 (B∞/G∞ − 1). Poisson’s ratio and fragility might be regarded as an important parameter that controls global plasticity of glass-forming alloys.

Copper was supplied to Sn–3.5Ag by electroplating Cu/Ni double under-bump metallization (UBM), and the amount of Cu was controlled by varying the Cu UBM thickness. Supposed Cu contents in the solder were; 0.2, 0.5, and 1.0 wt%, respectively, and the solder joint microstructure was investigated after 1, 5, and 10 reflows. In the case of specimens with 0.2 and 1.0 wt% Cu, only one type of intermetallic compound (IMC) formed, either (Cu,Ni)6Sn5 or (Ni,Cu)3Sn4, while two types formed in specimen with 0.5 wt% Cu. No correlation could be found between the solder joint microstructure and the ball shear test. However, drop test results showed two opposite trends. The drop resistance of 0.2 and 1.0 wt% Cu specimens was quite good initially but degraded dramatically with multiple reflows, in contrast to that of the 0.5 wt% Cu specimen, which was very poor after one reflow but improved substantially later on. The former was ascribed to thickening of IMC during reflow, while the latter was related to (Ni,Cu)3Sn4 thickening beneath (Cu,Ni)6Sn5 and subsequent spalling of (Cu,Ni)6Sn5 from (Ni,Cu)3Sn4.

Activation of polycrystalline silicon (poly-Si) thin films doped as n-type using selective ion implantation of phosphorous was performed employing field-enhanced rapid thermal annealing where rapid thermal annealing of halogen lamps is combined with alternating magnetic fields. The ion activation was evaluated using Hall effect measurements incorporating the resistivity, the charge carrier concentration, and the mobility. Statistical design of experiments is attempted in order to clarify the effects and interactions of processes variables on field-enhanced rapid thermal annealing towards ion activation: the three processing variables are furnace temperature, power of halogen lamp, and the alternating magnetic field. Hall effect measurements indicate that the furnace temperature and RTA power are found to be dominant in activating the doped polycrystalline Si in dose. The activation process results from the competition between charge carrier concentration and mobility: the increase in mobility is larger than the decrease in charge carrier concentration.

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.

The deformation behavior of Ti-based bulk metallic glass (BMG) and metallic glass matrix composite (MGMC), both having a multistep crystallization behavior upon heating, has been investigated in the supercooled liquid region. The BMG deforms homogeneously and exhibits moderate elongation to failure due to its multistep crystallization behavior, but shows a significant variation of the flow stress during deformation. For the MGMC containing an in situ β-phase, a stress-overshoot characteristic, observed in the BMG, is not presented, but elongation to failure is rather limited because the crystalline β-phase prevents the viscous flow of the amorphous phase. The different presence of the crystalline phases in the metallic glasses can differently affect the flow behavior of metallic glass in the supercooled liquid region.

Quasicrystalline coatings with various aluminum based systems were deposited onto 304 stainless steel substrates using two thermal spraying techniques; plasma spraying and high velocity oxy-fuel spraying. The friction and wear performances of the coatings were evaluated using two different testing devices, varying testing conditions and counterpart materials. Values of the friction coefficient were found to be strongly dependent on the testing devices and the counterpart materials, with values ranging from 0.15 to 0.4. In testing conditions corresponding to high sliding velocity, this study showed that the contact problem was posed over a third body system due to the formation of an intermediate layer. Values of the coefficient of friction were found to be approximately the same for all coating layers regardless of the thermal spraying techniques used, however, larger differences were obtained in the wear performance. The tribological properties were also evaluated at high temperature. It is noted that quasicrystal coating layers exhibit better friction and wear performances at 450oC than at room temperature. In comparison to potential coating candidate such as Cr2O3 for piston rings in automotive engines, tribological property of quasicrystalline coating layers seems to be promising one, however, wear performance need to be improved.

The thermal stability and crystallization behavior of melt spun amorphous Ti50Cu35Ni15-xSnx (x=0, 3, 5, 7) alloys has been studied in by thermal analysis (DSC and DTA) and X-ray diffractometry. Partial replacement of Ni by Sn up to 5 at % in Ti50Cu35Ni15 alloy improved thermal stability and glass forming ability. The onset temperature of the first exotherm increased from 739 to 756 K with increasing Sn content x from 0 to 5, and then decreased to 745 K for the alloy with x=7 due to change in crystallization sequence. Melt spun amorphous Ti50Cu35Ni12Sn3 and Ti50Cu35Ni10Sn5 alloys exhibit ΔTx exceeding 78 and 76 K, respectively, which is significantly larger than ΔTx of 46 K in Ti50Cu35Ni15 alloy. Amorphous Ti50Cu35Ni15 alloy crystallized by precipitation of supersaturated cubic Ti(Ni,Cu) phase followed by decomposition into a mixture of TiCu and TiNi at higher temperature. Amorphous Ti50Cu35Ni15-xSnx (x=3, 5) phase crystallized by precipitation of cubic Ti(Ni,Cu) phase, followed by transformation into a mixture of TiNi, TiCu, Ti3Sn phases. Amorphous Ti50Cu32Ni8Sn7 phase crystallized by co- precipitation of cubic Ti(Ni,Cu) phase and unidentified phase, followed by transformation into a mixture of TiNi, TiCu, Ti3Sn phases.

Currently, the most successful direct simulation of the solar granules (and the convection/radiation transition layer) is the three-dimensional (3D) model computed by Stein and Nordlund (1989). So far, there is no other similar 3D models available for comparison [however, see Ludwig et al. (1997) for a recent 2D calculation]. We are developing an alternative numerical approach to simulate the 3D radiation hydrodynamics of this layer. In this approach, the Eddington approximation is used to handle the radiation rather than solving the radiative transfer equations along rays, and the ADISM method (Chan and Wolff 1982) which solves the Navier Stokes equations in conservative forms is used to speed up the thermal relaxation of the fluid layer. We are in the process of testing the numerical accuracy of the codes. This paper summarizes the results of a test that illustrate the effects of vertical space resolution on the mean profiles of some important quantities.

BPSG films show good flow characteristics with the increase of boron and phosphorus concentration. As–deposited BPSG films with high boron and phosphorus concentration, however, have a dopant instability which results in film bursts, cracks, and precipitates, due to water absorption. Elimination of dopant instabilities of BPSG films by N2O plasma treatment is investigated. Film structure, composition and flow properties are evaluated by FT-IR, SIMS, and SEM, respectively. Dopant stability is examined after H2SO4 boiling. After H2SO4 boiling without N2O plasma treatment, BPSG films with high boron and phosphorus concentration show poor flow characteristics. Boron and phosphorus are leached out of the BPSG films by reaction with absorbed water during the H2SO4 boil. N2O plasma treatment results in a thin surface layer composed of Si-O-B bonds. These bonds do not dissolve in water. It is proposed that the thin layer consisting of Si-O-B bonds prevents the penetration of water into BPSG film during H2SO4 boiling.

We observed 3 mm transitions of several interstellar molecules toward star-forming regions in W58 and GL490 using the 14 m Daeduk Radio Telescope (Korea). We derive molecular abundances for the“broad” components observed with a high spectral resolution, which could represent the abundances of outflowing materials.

In this paper, the effect of atomic hydrogen on carbon impurity incorporation during the metalorganic-molecular-beam-epitaxy (MOMBE) growth of GaAs is studied. Atomic hydrogen was introduced into the MOMBE chamber during the growth by cracking molecular hydrogen with a high temperature cracker cell. Atomic hydrogen appears to be effective in reducing the background doping level of MOMBE-grown GaAs, presumably by reacting with hydrocarbon radicals. Background doping levels as low as 4 × 1014 cm−3 and room temperature hole mobilities as high as 430 cm2/V-sec were achieved. This result demonstrates that it is feasible to grow high quality GaAs films in MOMBE without using AsH3 or a high flux of As4by introducing atomic hydrogen into the chamber during the growth.

In this work, activation of Si implanted into GaAs-on-Si layers grown by molecular beam epitaxy (MBE) is studied. We have found that activation efficiency of implanted Si is lower in GaAs on Si than in bulk GaAs and varies widely. By studying the activation of non-amphoteric dopants such as Be and S, we have found that no donor- or acceptor-like defects exist in high concentrations in GaAs on Si and that amphoteric behavior of Si is the major compensation mechanism in MBE-grown GaAs on Si. Increased Si-acceptor concentration and S activation in GaAs on Si are apparently due to a high density of As vacancies which result from a low V(As):III(Ga) flux ratio during growth. The effect of the threading dislocations does not appear to be significant compared to that of As vacancies as no correlation is found between the density of threading dislocations and implanted Si activation.

High-Electron Mobility Transistors (HEMTs) can be prepared by growing alternating epitaxial layers of InAlAs and InGaAs on InP substrates. Lattice matched HEMTs are obtained by growing layers of InxAl(1-x)As and InyGa(1-y)As with x ≃ 0.5227 and y ≃ 0.5324. Varying the values of x and y by controlling the individual flux during molecular-beam epitaxial (MBE) growth, one can obtain pseudomorphic HEMTs. Pseudomorphic HEMTs may have superior electronic transport properties and larger conduction band discontinuity when compared to an unstrained one. The precise control of the composition is thus important to the properties of HEMTs. This control is however very difficult and the values of x and y may vary from run to run.

We will demonstrate in this paper the capability of a double crystal rocking curve (DCRC) on the structure characterization. All the structure information: including composition and thickness of both the buffer and top InAlAs layers and the active channel InGaAs layer, can be obtained from one x-ray diffraction measurement. It is accomplished through a computer simulation process of DCRCs. The structure parameters of the epitaxial layers are used to calculate (simulate) the DCRCs. The simulated one is then to compare with the experimental curves. During the simulation one or more of these structure parameters are adjusted until the best fitted DCRC is obtained. The limitation of DCRC in measuring small variations in layer thickness as well as the small changes in composition for both InAlAs and InGaAs layers will be discussed.