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A simple fabrication scheme of using silver-filled conductive tape to form flexible single crystalline Si–Pd Schottky diodes on a polymer substrate has been studied and reported previously. In this investigation, we studied the long term thermal stability of these flexible diodes on polymer annealed at 80 °C in open air for 1 year. The I–V characteristics of the diodes were measured periodically. We found that the barrier height of the Si–Pd diodes remained relatively unchanged at 0.795 eV ± 0.003 with an n-factor of 1.03 ± 0.03, and a series resistance of ∼110 Ω for diodes with a 950 μm diameter, which are almost identical to the values before annealing. The integrated structure stayed flexible to a similar curvature after 1 year. The stability of silver-filled conductive tape was investigated separately over the same period of time and under the same conditions. The resistance of two conductive tapes was found to quickly decrease from high initial values to significantly lower values, and remained constant over the course of the investigation. Based on these results, we conclude that this simple bonding technique of using conductive tape to fabricate flexible devices can be of useful value in practical applications.

An efficient top-emitting organic light-emitting diode (OLED) was formed of an organic stack sandwiched between a thick Ag anode and a semi-transparent Ag cathode. Interface modification was employed to reduce the injection barriers for both electron and hole from the Ag electrodes into the organic stack. The OLED exhibited superior current–voltage characteristics over a control device having an anode of indium tin oxide. The color could be tuned by varying the thickness of the organic stack. At a thickness of 105 nm, the OLED showed a narrow green emission peak with a device efficiency of about 7.64 cd/A, much greater than 3.36 cd/A obtained from the control device. The color tuning and the efficiency enhancement are attributed to the formation of an optical microcavity in the OLED with Ag electrodes.

Traditional ideas concerning environmental management tend to be based upon simple relationships between cause and effect. Such approaches make the design of environmental management strategies fairly straightforward: once the cause of a problem has been identified, it is necessary only to address the cause and/or help the system to recover through some sort of attempt at restoration. In the case of shallow lake eutrophication, research in the 1960s and 1970s identified phosphorus as the key control on the trophic state of a lake and, hence, recommended reductions in the supply of phosphorus to lakes as the necessary remedial measure. However, subsequent research has illustrated that such measures were not always successful. This article reviews the science of shallow lake eutrophication to demonstrate the role of ecosystem-specific biological and chemical interactions in conditioning the response of lakes to remedial measures and, hence, shows how new ideas of complexity help us to understand the behaviour of lake ecosystems so that we can develop alternative environmental management strategies.

Nickel monosilicide (NiSi) has been well recognized as a promising silicide for future ULSI devices. It can have low resistivity of 15 μΩ cm on deep submicron lines and after high temperature (>600°C) annealing. This work studies the resistivity and thermal stability of thin NiSi layer on B, As, P-doped and in situ boron doped deep submicron polycrystalline silicon (poly-Si) lines after 500–800°C/1 h of annealing. The stability of NiSi on crystalline silicon (c-Si), poly-Si and amorphous silicon (a-Si) film will also be studied.

Thermal stability of cobalt and nickel silicides on crystalline Si (c-Si) and amorphous Si (a-Si) has been investigated. We have found that CoSi 2 is thermally stable on a-Si and c-Si substrates up to 950°C for 30 min. NiSi is stable and shows low resistivity on c-Si at around 700°C for 30 min, but is unstable on a-Si substrate even after annealing at 400°C.

We have found that very low resistivity NiSi can be thermally stable and independent of linewidth in boron-doped and in-situ boron-doped deep submicron poly-Si lines up to 650–750°C for 0.5 and 1 h annealing, and for linewidths as narrow as 0.2–0.1 μ m. It widens the process tolerance and thermal budget windows for NiSi, and suggests that NiSi is a very promising contact material candidate for future ultra-large-scale-integration devices.

Bacterial feeding nematodes excrete N assimilated in excess of that required for growth. Because metabolic and developmental rates differ among nematode species, we hypothesized that their contribution to N mineralization in soil would differ. Sand-column microcosms amended with an organic substrate, bacteria, and with or without bacterial-feeding nematodes, were leached at 3-d intervals. Cumulative N, as NH 4 + or NO 3 - , leached from columns containing nematodes was consistently greater than from columns without nematodes. Maximum N-mineralization rates for populations of rhabditid nematodes, which predominated in field soils early in the summer were at lower temperatures than those for cephalobid nematodes, which predominated later in the summer. For an organic substrate with C-to-N ratio of 11:1, rates of N mineralization among species of different body size were similar, ranging between 0.0012 and 0.0058 μg-N nematode-1 d-1, mainly as NH 4 + . Smaller nematodes mineralized more N per unit of body weight than larger nematodes. We hypothesized that at low C-to-N ratios of the organic substrate, bacterial growth is C-limited and N-immobilization will be minimal; at high C-to-N ratios bacterial growth will be N-limited and there may be rapid immobilization of newly-mineralized N. Consequently, net N mineralization in the presence of nematodes will be lower when the organic substrate has a high C-to-N ratio. In experiments with different nematode species, net mineralization and the nematode contribution to mineralization generally decreased with increasing C-to-N ratio, consistent with the hypothesis; however, there were exceptions.

Summary-Ibacterial-feeding nematodes participate in nitrogen mineralization in decomposition food webs to an extent determined by metabolic and behavioral attributes, by life history, and by the relative C-to-N ratios of the nematodes and their bacterial prey. The mean C-to-N ratio for eight nematode species cultured on Escherichia coli on agar was 5.89 (range 5.16-6.83). The mean C-to-N ratio was similar, although with greater variability among species, when nematodes were cultured in soil on a range of soil bacteria. The mean C-to-N ratio of five isolates of soil bacteria and E. coli was 4.12 (range 3.65-4.92). Where food was not limiting, production-to-assimilation ratios ranged from 0.58 to 0.86 and respiration-to-assimilation ratios from 0.14 to 0.42. The excess N assimilated during growth and egg production, and the excess N assimilated to meet the C needs of respiration, were similar across species at 20°C. The excess N from both sources provides an estimate of the amount of N excreted by each nematode during the life course. The weight of bacteria necessary to meet the growth and respiration costs at 20°C ranged from 0.87 pgpg-nematode -’ d-’ for Cephalobus persegnis to 1.99 pg pg-nematode-’ d-* for Bursilla labiata, providing estimated consumption rates between 6.61 x 10’ and 15.22 x 10’ bacterial cells pg-nematode-’ d-‘. At a field site, we estimate that the bacterial-feedin f nematode community in the top 15 cm soil mineralized N at rates increasing to 1.01 pg-N g-soil-’ din rhizospheir soil. On a monthly basis, the community contributed 0.28 kg-N ha-’ in April, 0.98 kgN ha-’ in Mly and 1.38 kg-N ha-’ in June in bulk soil. Contributions in the rhizosphere would be considerably greater depending on the ratio of rhizosphere to bulk soil. The contribution of individual species to N mineralization in the rhizosphere varied through the first 3 months of the summer growing season as a function of their abundance and their metabolic and development rates in relation to temperature. Rhabditis cucumeris was the predominant contributor in April; there were similar contributions by Acrobeloides bodenheimeri, B. labiata, Cruznema tripartitum, and R. cucumeris in May; A. bodenheimeri and B. labiata were the major contributors in June. 0 1997 Elsevier Science Ltd

Nematode communities were monitored intensively through a tomato (Lycopersicon esculentum L.) growing season in plots managed by conventional and organic farming practices. The temporal dynamics of individual species of bacterial-feeding nematodes differed and suggested differing importance of species in their contribution to N-mineralization in the organically managed soil. Species with r-selected, colonizer characteristics were most responsive to incorporation of organic matter and the subsequent increase of microbial biomass. Bacterial-feeding nematode populations were lowest early in the growing season, when tomato plants exhibited symptoms of nitrogen deficiency. We hypothesize that increasing abundance, biomass and activity of these nematodes in the spring by organic matter incorporation at the end of the previous crop would reduce the observed nitrogen stress. Fungal-feeding nematodes were more abundant in the conventional than the organic plots during periods of organic matter decomposition, possibly related to the higher carbon:nitrogen ratios of the crop residues incorporated into the conventional soils than of the manures and leguminous cover crops incorporated into the organic soils. Predaceous and omnivore nematode populations were low in both farming systems, and plant-parasitic nematode species reflected the crop sequences in rotations used in each system.

By grazing on bacteria, bacterial-feeding nematodes participate in decomposition food webs and N mineralization to an extent determined by metabolic and behavioral attributes and by life history. We determined the stage-specific development and fecundity rates for seven species on a physiological time scale to allow time and temperature-varying predictions of population progressions. Development from egg to adult of four species in the Rhabditidae (Bursilla labiata, Caenorhabditis elegans, Cruznema tripartitum and Rhabditis cucumeris) was faster than that for three species in the Cephalobidae (Acrobeloides bodenheimeri, A. buetschlii and Cephalobus persegnis) on a Julian time (calendar) basis at 20°C. Development in the Rhabditidae was generally faster on a physiological (degree-day) time scale as well, but those times are not directly comparable as the basal threshold for degree-day (DD) accumulation differed among the species. The fecundity period for females of the seven species varied between 55 and 75% of the total duration of the life course, during which they produced between 125 eggs (B. labiata) and 567 eggs (C. tripartitum). Simulated population growth under favorable temperature conditions, using parameter values determined in these studies, indicated rapid population growth in the large-bodied, highly-fecund rhabditid species (R. cucumeris and C. tripartitum). Population growth was intermediate in the small-bodied, less-fecund rhabditids with short egg-production periods (B. labiata), slower in the cephalobids (A. bodenheimeri and A. buetschlii) and slowest in C. persegnis. R. cucumeris spent a greater proportion of its development time in the egg stage than did any of the other species.

BACKGROUND - : During follow-up of between 1 and 3 years in the Randomized Evaluation of Long-term Anticoagulation Therapy (RE-LY) trial, 2 doses of dabigatran etexilate were shown to be effective and safe for the prevention of stroke or systemic embolism in patients with atrial fibrillation. There is a need for longer-term follow-up of patients on dabigatran and for further data comparing the 2 dabigatran doses. METHODS AND RESULTS - : Patients randomly assigned to dabigatran in RE-LY were eligible for the Long-term Multicenter Extension of Dabigatran Treatment in Patients with Atrial Fibrillation (RELY-ABLE) trial if they had not permanently discontinued study medication at the time of their final RE-LY study visit. Enrolled patients continued to receive the double-blind dabigatran dose received in RE-LY, for up to 28 months of follow up after RE-LY (median follow-up, 2.3 years). There were 5851 patients enrolled, representing 48% of patients originally randomly assigned to receive dabigatran in RE-LY and 86% of RELY-ABLE-eligible patients. Rates of stroke or systemic embolism were 1.46% and 1.60%/y on dabigatran 150 and 110 mg twice daily, respectively (hazard ratio, 0.91; 95% confidence interval, 0.69-1.20). Rates of major hemorrhage were 3.74% and 2.99%/y on dabigatran 150 and 110 mg (hazard ratio, 1.26; 95% confidence interval, 1.04-1.53). Rates of death were 3.02% and 3.10%/y (hazard ratio, 0.97; 95% confidence interval, 0.80-1.19). Rates of hemorrhagic stroke were 0.13% and 0.14%/y. CONCLUSIONS - : During 2.3 years of continued treatment with dabigatran after RE-LY, there was a higher rate of major bleeding with dabigatran 150 mg twice daily in comparison with 110 mg, and similar rates of stroke and death. CLINICAL TRIAL REGISTRATION - : URL: http://www.clinicaltrials.gov. Unique identifier: NCT00808067. © 2013 American Heart Association, Inc.

By grazing on bacteria, bacterial-feeding nematodes participate in decomposition food webs and N mineralization to an extent determined by metabolic and behavioral attributes and by life history. We studied the respiratory and metabolic activities of 8 species of bacterial-feeding nematodes at 5 temperatures by measuring the rate of CO2 evolution with an IR gas analyzer. We developed a method for determining size- or stage-specific respiration rates from measurements made on populations of varied stage-structure. Species from a single field site exhibited different thermal optima and temperature-niche breadths for respiratory and metabolic activity. Respiration rates of adults ranged between 1.25–8.80 nl O2 h−1 at 20°C among the species. Metabolic rates of adults ranged from 1.15 nl O2 μg(fresh wt)−1 h−1 for Rhabditis cucumeris Andrassy to 4.43 nl O2 μg(fresh wt)−1 h−1 for Bursilla labiata Andrassy at 20°C. At each temperature, metabolic rates of nematodes of similar size varied with thermal adaptation of the species. Metabolic rates of Cruznema tripartitum Zullini and Cephalobus persegnis Bastian were more sensitive to temperature change than were those of Acrobeloides bodenheimeri Thorne, A. buetschlii Steiner and Buhrer and Panagrolaimus detritophagus Fuchs. C. persegnis exhibited the greatest total metabolic activity cross a range of temperatures, and P. detritophagus the least. Observed differences in thermal adaptation may contribute to the predominance of species in the nematode community at different times during the year or at different depths in the soil.

Growers converting from conventional to low-input and organic farming systems must rely on organic sources for adequate soil fertility. At the Sustainable Agriculture Farming Systems (SAFS) project at UC Davis, we measured soil fertility and biological parameters in four farming systems. By the end of the first 4 years, pH and percent nitrogen were consistently higher in organic and low-input than conventional plots for all crops. Levels of organic matter, phosphorus and potassium were significantly higher in the organic than conventional 2-year plots. Microbial biomass levels were consistently higher in organic and low-input systems, while plant parasitic nematode numbers were consistently lower. Nitrogen deficiency appeared to be a problem in organic tomatoes during the transition period. More research is needed into the dynamics of soil nutrient availability in low-input systems. For instance, we may need to develop new methods of assessing soil fertility in organically fertilized systems.

The interactions between metal and III–V compound semiconductors have been under increasingly more intensive investigation since the early 1980's. Over the years rather significant progress in understanding the interactions has been made by various laboratories. In this discussion, we emphasize solid state reactions that are pertinent to the formation of non-spiking contacts to n- and p-type AlGaAs and GaAs, as well as those that could induce compositional disordering in III–V superlattice structures. Examples are given to illustrate the diverse application of simple reactions to microelectronics and optoelectronics.

Thermal interdiffusion in Si/Ge layered structures shows large variations in diffusivity between Si/Ge amorphous multilayer films and symmetrically strained superlattice structures. Amorphous layered structures exhibit much higher diffusivities and much lower activation energy for interdiffusion. We have used Rutherford backscattering (RBS) and transmission electron microscopy (TEM) to (1) investigate the mixing behavior in Ge/Si structures under ion mixing condition, (2) study the dependence of mixing on the microstructure of the multilayered films (amorphous layers vs. crystalline layers) and (3) study the effects of electrically active ions (e.g. A.s+ ions) on ion mixing behavior. We found that the ion mixing efficiency of the Si/Ge system shows two regimes upon ion irradiation: a thermally activated regime where the efficiency of mixing increases exponentially with the irradiation temperature and a nonthermal regime where the amount of mixing is independent of the irradiation temperature. The critical temperature for the onset of the thermally activated regime is found to be around 200°C. Comparison between thermal interdiffusion and ion-induced intermixing in the Si/Ge system is also made.

Different wafer bonding techniques for heterogeneous integration are compared; in particular, the advantages and disadvantages of metal bonding using isothermal solidification (ITS) process are investigated. In applying the ITS metal bonding to Si and GaAs integrated circuits, two distinct approaches - pre-patterning and post-patterning, are developed and the resulting metal bond properties, such as electrical contact and thermal conductivities, are presented.

Two approaches have been used to fabricate stable photoelastic waveguides with planarized surfaces on GaAs-AlGaAs heterostructures. The first approach uses tensile Ni/sub 3/GaAs stressors formed by metal-semiconductor reactions. The second approach uses inert, refractory and compressive stressors, such as RF sputtered W and RF co-sputtered WNi films. For comparison purposes, ridge waveguides have also been fabricated using the same heterostructure by a dry etching technique. Optical losses of photoelastic waveguides, measured by Fabry-Perot (FP) method at a wavelength of 1.53 /spl mu/m, are comparable to or better than those of the ridge waveguides. Material loss appears to be the primary loss mechanism in both photoelastic and ridge waveguides. These results indicate that the photoelastic waveguide processing technique reported in this study is a promising alternative to commonly used dry etching techniques for planarization.

Guided-wave components are essential elements in optical fiber communication and signal processing systems. For 1.3-1.5 /spl mu/m wavelength applications, it is of interest to develop low loss optical waveguides on InP substrate. In this work, low-loss InGaAs-InP planar photoelastic waveguides using metal stresser stripes have been demonstrated for the first time. >

Salicidation is a well known technique to suppress the floating body effect because the silicide near the source/body junction acts as a sink for holes. In this paper, we investigate the effect of nickel silicide layers of varying thickness on the drain current kink effect, the anomalous subthreshold slope and the breakdown voltage in partially depleted SOI-MOSFET. We demonstrate that deep salicidation is highly effective in suppressing floating body effects.

High resolution and analytical transmission electron microscopy was applied to characterize the microstructure of Al/Ti and W/Al/Ti ohmic contacts to AlGaN/GaN HFET structures. Formation of a 15-25 nm thick interfacial AlTi/sub 2/N layer appears to be essential for ohmic contract behavior indicating a tunneling contact mechanism. Contact resistance was found to depend on the structure and composition of the metal and AlGaN layers, and on atomic structure of the interface. Contact resistivity increases with Al fraction in the AlGaN layer.

Mesa type fused InGaAs/Si separated absorption and multiplication APDs with a diameter of 130 /spl mu/m have been fabricated on n-type Si substrate. Substantial dark current reduction has been achieved compared with the published data for fused InGaAs/Si APDs. Dark current densities as low as 0.23 mA/cm/sup 2/ at -5 V and 3 mA/cm/sup 2/ at a gain of 10 are reported. Our improved dark current even though is still 2 orders larger than the conventional mesa-structure InGaAs/InP APD lower excess noise level is expected due to the larger difference between the electron and hole ionization coefficients of Si.

I-V characteristics of the GaN/AlGaN/GaN heterostructures show that the barrier behaves like a Schottky barrier with controllable barrier height. Low temperature I-V measurement shows that a defect-assisted tunneling mechanism may dominate the current transport across the barrier.

We have demonstrated avalanche gain in InGaAs-Si fused PIN photodiode at low bias range. Simulation from a theory based upon the interface states introduced by the fusion process appears to explain the observed gain behavior of the photodiode.

Survival and respiration rates of the bacterial-feeding nematode Cruznema tripartitum after incubation in soil for 48 hr provided a useful bioassay of the presence and concentration level of biologically active toxicants. The assay provided an indication of toxicant activity at sublethal levels, and a means of determining when the toxicant had declined to levels not deleterious to physiological function. Assays of soil contaminants based on the community structure of resident soil nematodes were more useful in undisturbed soils than in agricultural soils where the range of taxa was relatively narrow. Assays involving measurement of survival and respiration rates of nematodes after immersion in an aqueous extract of contaminated soils were not useful due to degradation and loss of contaminant during the extraction process.

This research is a collaborative program between the University of California at San Diego and Cornell University to investigate the phenomenon of ion mixing in semiconductor layered structures. The research effort also involves interactions with Oak Ridge National Laboratory under the Surface Modification and Characterization Collaborative Research Center Program. During the current period of investigation, we investigated parameters that could affect ion-mixing rates in semiconductors. We found that the use of shallow dopants as the mixing ion did not increase the mixing rate, thus indicating that electrically active ions (or the Fermi level) do not play a significant role in ion-mixing. On the other hand, the presence of mismatch strain in Ge/Si layered structures can affect the mixing rate, especially in the temperature independent regime. Mismatch strain can also affect the solid-phase regrowth kinetics of amorphous layers of Ge-Si alloys. In summary, we found that ion mixing kinetics depend primarily on the ion and the target mass and the target temperature. Mixing rates can also be affected, to a certain extent, by thermodynamic driving forces (such as the cohesive energy and the stored strain energy of the system). Impurities do no play a significant role in mixing kinetics. 1 fig.,more » 1 tab.« less

Interactions induced by ion irradiation are generally considered to be non-equilibrium processes, whereas phase diagrams are determined by phase equilibria. These two entities are seemingly unrelated. However, if one assumes that quasi-equilibrium conditions prevail after the prompt events, subsequent reactions are driven toward equilibrium by thermodynamical forces. Under this assumption, ion-induced reactions are related to equilibrium and therefore to phase diagrams. This relationship can be seen in the similarity that exists in thin films between reactions induced by ion irradiation and reactions induced by thermal annealing. In the latter case, phase diagrams have been used to predict the phase sequence ofstable compound formation, notably so in cases of silicide formation. Ion-induced mixing not only can lead to stable compound formation, but also to metastable alloy formation. In some metal-metal systems, terminal solubilities can be greatly extended by ion mixing. In other cases, where the two constituents of the system have different crystal structures, extension of terminal solubility from both sides of the phase diagram eventually becomes structurally incompatible and a glassy (amorphous) mixture can form. The composition range where this bifurcation is likely to occur is in the two-phase regions of the phase diagram. These concepts are potentially useful guides in selecting metal pairs that from metallic glasses by ion mixing. In this report, phenomenological correlation between stable (and metastable) phase formation and phase diagram is discussed in terms of recent experimental data.

High purity single crystals of Ta and Mo oriented for (101)[111] single slip were tested in tension over the range of temperatures up to 620°K at two strain rates. Activation energies and activation volumes were determined. Analyses of the data revealed that they were in good agreement with the Peierls mechanism.

The properties of sputtered multilayer metal films have been examined as a function of power applied during sputtering. Sputtered conductors can be used successfully as terminals for Ta2N resistors and as counterelectrodes for tantalum film capacitors when the proper sputter conditions are chosen.

The electrical and structural properties of three layer Ti-Pd-Au films which are widely used for interconnections and terminations in thin film circuits change upon heat treatment at elevated temperatures. The annealing can cause stress relaxation, interdiffusion between the different layers and diffusion-induced structural changes. The objective of this investigation was to study the effect of aging at temperatures between 284° and 425°C on the mechanical and structural properties of these conductor films. It was found that the stresses in the Au film on Pd-Ti were independent of the substrate material and were lower than those of the Au films deposited directly on the Ti bonding layer. During aging, substantial interdiffusion between Au and Pd took place and it was found that the diffusion rate of Pd was higher than that of Au.

RF sputter-deposited tantalum-silicon films on GaAs have been investigated using four-point probe, glancing-angle X-ray diffraction, Auger electron spectroscopy, and MeV4He+backscattering spectrometry as a function of annealing up to 850°C. Experimental results show that: 1) there is no observable Ta or Si migration from the TaSi 2 overlayer into the GaAs substrate; 2) the structure of the As-sputtered film is amorphous and crystallization into a polycrystalline TaSi 2 layer occurs at ∼ 500°C accompanied by a reduction in electrical resistivity. After annealing at 650°C, As and/or Ga appear to have migrated into the TaSi 2 layer. The amount of this migration remains unchanged up to an annealing temperature of 850°C. On the other hand, migration of Ta and/or Si into the GaAs substrate is not detected up to 850°C. This absence of the Ta and/or Si migration contributes to the stability of the Schottky-diode characteristics against annealing reported previously.

GaAs MESFET's with non-alloyed ohmic contacts have been achieved through a solid phase reaction of the Ge/Pd/GaAs(xtl) structure upon annealing at 325° C for 30 min. Different Au-based overlayers over Ge/Pd have been tested for device applications and compared with a conventional AuGeNi contact. The thermal stability of the contact resistivity has been evaluated through long-term storages at 300°C.

GaAs MESFETs with nonalloyed ohmic contacts, achieved through a solid phase reaction of a Ge/Pd/GaAs (xtl) structure, have been realised and tested at DC and RF. Their contact resistivity and electrical performances are better than those of similar devices with conventional AuGeNi ohmic contacts.

318. In vitro microsomal hepatic epoxidation of bromobenzene in rats and mice is presented in this study. Formation of o-bromophenol via bromobenzene-2,3-epoxide and p-bromophenol via bromobenzene-3,4-epoxide was assayed enzymatically and identified by a new, rapid and sensitive gas-liquid chromatography method using electron capture detection. Pretreatment of the animals with phenobarbital caused significant increases in both pathways whereas 3-methylcholanthrene or b-naphthoflavone caused a selective and marked increase of only the 2,3-epoxide pathway. Sodium dodecyl sulfate-gel electrophoresis of microsomal preparations resolved multiple forms of cytochrome P-450 and indicated that different forms of the heme protein were responsible for the formation of o-bromophenol and p-bromophenol. It is of interest that various inducers augment particular pathways for a common substrate especially since bromobenzene-3,4-epoxide and not the bromobenzene-2,3-epoxide has been proposed as the cytotoxic reactive metabolite of bromobenzene.

In this work, we found that very low resistivity NiSi can be thermally stable and is independent of linewidth for deep submicron p-type poly-Si lines up to 700-750/spl deg/C for 0.5 and 1 hr annealing, and for linewidths as narrow as 0.2-0.1 /spl mu/m. It widens the thermal budget windows and process tolerance for NiSi and further suggests that NiSi is a very promising contact material candidate for future ULSI devices.

We will present a comparison between GaN grown on c - and r -plane sapphire by gas-source molecular beam epitaxy (GSMBE) using solid source elemental Ga with uncracked ammonia (NH 3 ). Improved GaN film quality was found for samples grown at substrate temperatures above 700°C with optimized temperatures at 780°C. GaN deposited on a low-temperature (∼ 350°C) GaN buffer layer grown using an rf-plasma radical beam source exhibited poor photoluminescence (PL) intensity and carrier mobility while SEM analysis showed smooth GaN surface morphologies. GaN deposited on an ammonia-grown low-temperature (∼ 550°C) GaN or AlN buffer were found to have improved PL intensity and line widths, GaN surface morphology and carrier mobility. X-ray rocking curve (XRC) data showed that the GaN crystal quality improved as a function of increasing substrate growth temperature independent of buffer layer implementation.

Silicon samples diffused with phosphorus at 1050°C and subsequently annealed at 600°C or 700°C in vacuum or O 2 ambients were found to contain extrinsic stacking faults or misfit dislocations. We propose that silicon interstitials are generated to form the extended defects to relieve strain.