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Chemical deposition of polycrystalline silicon is finding increasing application in the fabrication of in-* Electrochemical Society Active Member.tegrated circuits, such as silicon-gate MOS devices (1), dielectric isolations (2), and two-phase CCD's (3). Polycrystalline silicon is also used in photomask fabrication. Doping of silicon films can occur during an in situ codeposition or during a subsequent high tem-) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.159.70.209 Downloaded on 2015-04-11 to IP

Second and third order elastic constants of NaCI, NaBr, KF, KCI, KBr, and RbBr have been calculated using the Born model of ionic solids. Short range repulsive interactions have been included up to second nearest neighbors using an expression of the form A exp ( -r / b ) where b is the repulsive parameter. A distinction is made between the like and unlike ion interactions. Van der Wads terms are also included. When the room temperature lattice parameter is used, the elastic constants satisfy the Cauchy relations. Experimental data show that many of the alkali halides fail to satisfy the Cauchy relations. This aspect is examined by using the quasi-harmonic approximation as developed by Leibfried and his associates. Linear temperature coefficients of the elastic constants are also calculated in the high temperature limit. I n order to assess the contributions of the van der Waals terms, elastic constants are also calculated by dropping the van der Waals terms in the expressions for the elastic constants. Calculated values of the elastic constants are compared with the available experimental data.Die elastischen Konstanten zweiter und dritter Ordnung werden mit dem Bornschen Modell fur Ionenfestkorper fur NaCI, NaBr, KF, KCI, KBr und RbBr herechnet. Kurzreichende Abstohngswechselwirkung wird bis zu den zweiten nachsten Nachbarn durch einen Ausdruck der Form A exp (-r/b), mit b als Abstohngsparameter, berucksichtigt. Es wird zwischen der Wechselwirkung gleicher und ungleicher Ionen unterschieden. Van der Waals-Terme werden ebenfalls berucksichtigt. Wenn die Gitterkonstante bei Zimmertemperatur benutzt wird, erfullen die elastischen Konstanten die Cauchy-Relationen. Experimentelle Ergebnisse zeigen, daB viele Alkalihalogenide die Cauchy-Relationen nicht erfullen. Diese Erscheinung wird mit der von Leibfried und Mitarbeitern entwickelten quasi-harmonischen Naherung untersucht. I m Grenzfall hoher Temperaturen werden auch die linearen Temperaturkoeffizienten der elastischen Konstanten berechnet. Urn den Beitrag der Van der Waals-Terme abzuschatzen, werden die elastischen Konstanten berechnet, indem die Van der Waals-Terme in die Ausdrucke fur die elastischen Konstanten einbezogen werden. Die berechneten Werte fur die elastischen Konstanten werden mit den zur Verfugung stehenden experimentellen Werten verglichen.

The spatial variation of minority-carrier diffusion length in the vicinity of a grain boundary for a polycrystalline silicon sheet has been measured by the use of the EBIC technique. The effect of such a variation on solar-cell output has then been computed as a function of grain size. Calculations show that the cell output drops considerably for grain size smaller than three times the bulk diffusion length.

Auger electron spectroscopy has been used to evaluate the chemical state of silicon (111) surfaces cleaned by various liquid reagents, ion sputtering, and plasma treatment. The two most common impurities observed were carbon and oxygen. Results indicated that liquid reagent cleaning produced surfaces which were heavily contaminated with carbon, and that when oxidizing reagents were used, carbon contamination could be kept to a minimum. Sputtering was toured to be an unsatisfactory method of cleaning because slices became activated after sputtering and adsorbed impurities from the atmosphere when removed from the vacuum system. Plasma treatment was the most effective of the three types of cleanups used, producing surfaces with the lowest carbon concentrations. One exception was CF4 plasma which was shown to deposit carbon on the surface.A large number of processes are used by the semiconductor industry for the cleaning of silicon prior to process steps such as oxidation, diffusion, and metal deposition. The chemical state of the surface after cleanup has not been systematically investigated, resuiting in wasteful consumption of chemicals and the use of "overkill" in slice cleanup. We have investigated the effect of eight liquid reagent cleaning sequences, six plasma cleanups, argon sputtering, and deionized water rinsing on silicon surfaces.Auger electron spectroscopy (AES) has been shown to be a useful and highly sensitive tool for the study of etched silicon (i) and chemically cleaned germanium surfaces (2), particularly for the determination of the effects of carbon contamination (3), and has been chosen for this study. The principles of AES have been described in the literature (4-6).In this work carbon was found to be one of the major contaminants, along with oxygen, on chemically cleaned silicon surfaces and the effectiveness of various chemicals, plasma, and sputtering for the removal of carbon have been examined. ExperimentalThe samples used were 0.76 mm thick mechanically polished 10 ohm-cm boron-doped silicon (111) slices. The slices were cut from the same boule in order to minimize the effect of the bulk material on the surface contamination. Strips from the slices were then subjected to liquid cleaning, argon ion bombardment, or plasma cleaning All reagents used were (ACS) Low Mobile Ion Grade and the deionized water used for rinsing had a resistivity of 18 megohms.Details of the process sequences used to prepare the samples are given in Tables I (liquid reagent), II (argon ion sputter), and III (plasma).Argon ion bombardment was performed with a Varian ion gun (Model 981-1045) at 5 X 10 -5 Torr argon (Matheson, Research Grade) pressure, which produced a 12 mm diameter ion beam at 600 eV energy. Samples could be heated inside the Varian Cylindrical Mirror Analyzer system (Model 981-2607) by conduction from radlatively heated stainless steel blocks on which they were mounted for analysis. Chromel-Alumel thermocouples, spot welded on stainless steel retaining strips used to press the samples to