THE STRENGTH AND STRUCTURE OF EPITAXIAL FILMS.
Final rept. 1 Mar 65-1 Mar 66,
MIDWEST RESEARCH INST KANSAS CITY MO
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A series of epitaxial gold films was grown on sodium chloride substrates under a variety of conditions to determine effects of various types of grown-in impurities. Tensile tests were attempted on seven films of approximately 1,000 A thickness, but because of localized flaws or damage incurred during mounting, no useful tensile data were obtained. Consequently, interests centered primarily on changes in the microstructure of the films as determined by electron transmission microscopy, and on their implications for related tensile properties. Films were deposited at rates of the order of l Asec in an all-metal bakeable system capable of operation in the ultrahigh vacuum range. Both cleaved and polished substrates were used at temperatures ranging between 280 C and 400 C. Micrographs of films prepared in a 10 to the-7th power torr vacuum were compared with those of films grown in approximately 0.00001 torr atmospheres of dry air and H2O. It was established that these contaminants produced only secondary effects on the film structure. By contrast, contamination with molybdenum-oxide produced by the reaction of the crucible with an oxidizing atmosphere change the structure completely and virtually eliminated visible stacking faults or twins. Similarly the addition of 1.5 atomic per cent Cu to the melt and subsequent evaporation to completion resulted in alloy films with very little regular structure. Author