53 research outputs found

    Techniques for Materials Microanalysis

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    The science and technology of ultrasmall three-dimensional materials systems has been developing rapidly the last 20 years or so. Catalysts, coatings, composites, as well as electronic device structures—all rely on materials properties on an atomic scale. To develop such new materials and understand the chemical and physical properties that determine their unique behavior, we also require analytical tools with atomic level spatial resolution and at the same time the desired measurement capability. This need, along with extensive scientific interest in the fundamental chemical and physical properties of free surfaces, has led to the continued development of microanalytical chemical analysis techniques over the past 20 years. Most readers will be familiar with many of these techniques with acronyms such as AES, XPS, RBS, SIMS, ESCA, etc. This issue of the MRS BULLETIN will review some recent advances in the development of these techniques as well as introduce new techniques with significant advantages over the older ones.As you can see from the thickness of this issue, it is difficult to cover the entire field in a finite amount of space. This led us to limit the discussion to those microanalytical tools which can easily be applied to the analysis of buried interface structures such as those found in semiconductor devices.</jats:p

    The Apocalypse in the early church Christ, eschaton, and millennium

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    SIGLEAvailable from British Library Document Supply Centre- DSC:D175413 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

    Optimized model for university/industry interactions: development of design coupled manufacturing tools for infrared imagers

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    Phase Stability of Molybdenum-Silicon Nitride-Silicon Mis Schottky Diode at High Temperatures

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    ABSTRACTPreviously our group[1,2] has demonstrated metal-thin insulator- silicon Schottky diode structures which allow the Si Schottky barrier height to be adjusted over nearly the full range of the silicon band gap by appropriate choice of insulator thickness and metal. However, previous attempts to achieve a structure with a high barrier height to p-type that is stable above 400C(using primarily Titanium) have failed. In this paper we report on results for a metal, Molybdenum, which has a stable tie line to Sio2 and Si3N4 in metal-silicon-oxygen(nitrogen) ternary phase diagram which leads to a more stable system.</jats:p

    The Effect of Aqueous Chemical Cleaning Procedures on Schottky Contacts to N-Type Gaas

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    ABSTRACTThe effect of interfacial oxides and impurities left by aqueous chemical cleaning procedures on the n-type Schottky barrier heights of various metal-GaAs contacts have been examined as a function of annealing temperature. The as-deposited barrier heights of metals which are expected to be reactive with respect to the native oxides of GaAs (Mn, Cr, Al and Ti) were the most sensitive to variations in the residual oxide thickness. Omitting the final oxide etch from the cleaning sequence resulted in a 50 to 60 meV reduction in the as-deposited barrier height of these metals. However annealing these contacts at temperatures as low as 175 °C results in a barrier height that is independent of the initial surface clean. In contrast, for metals which are expected to be unreactive with respect to the native oxides of GaAs (Ni, Au, Cu and Ag) the pre-deposition cleaning procedure had little effect on either the as-deposited or the annealed Schottky barrier heights.</jats:p

    An elementary model of neutral and ion sputtering yields

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    New Models of Sputtering and Ion Knock-On Mixing

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    Fundamental Mechanisms for Hg Vacancy and Interstitial Modeling in Mercury Cadmium Telluride

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    ABSTRACTDue to the large concentration of electrically active defects in Hg1-xCdxTe, it is important to properly account for them when designing fabrication processes for infrared focal plane arrays (IRFPAs). Stanford University's Mercury Cadmium Telluride Process Simulator, SUMerCad, is being developed to simulate the interaction of native defects and dopants in Hg0.8Cd0.2Te in order to accurately model various processing techniques. Non-linear coupled differential equations are used to model the physics of the diffusion mechanisms, rather than extrapolating the diffusion profiles from experimental data. The fundamental constants for the point defects were obtained by exercising the simulator over the various parameter spaces and comparing the results to experimental work and best principle calculations. The methodologies used, point defect mechanisms modeled, and parameters determined are discussed.</jats:p
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