The epitaxial quality of GexSi1minus;xfilms grown on Silang;100rang; by a novel laserhyphen;assisted technique has been investigated for compositions in the rangexle;0.37 and thicknesses between 50 and 500 nm. Epitaxy is induced during electron beam deposition of GexSi1minus;xfilms on Si substrates by pulses of an excimer laser operating at 308 nm with 30 ns pulse duration. Good epitaxial growth is obtained for 50 nm films forxle;0.04 on chemically cleaned Si(100) surfaces even in the presence of substantial fluorine coverage. Using a predeposition/crystallization of a 50 nm purehyphen;Si buffer layer, good epitaxy is then obtained in 50 nm films forx=0.05ndash;0.13. Atx=0.07, defecthyphen;free alloys have been grown up to thicknesses of 0.5 mgr;m. However, for films with compositions above 19 at.percnt; Ge, dislocations at a nearly constant density of ape;10 mgr;m/mgr;m2are observed. This uniform density suggests a breakdown mechanism other than simple strain relaxation.
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