Crystallization of SiO by HE+ bombardment

Amorphous silicon monoxide (∼ 100 nm thick), prepared by evaporation on rock salt, was bombarded with 80 keV He+ ions. Examination by transmission electron microscopy revealed that crystalline regions up to 15 nm diameter were produced throughout the amorphous matrix when the ion flux was greater than 2.0 x 1018 ions/m2-sec in which the sample temperature was 850 ± C due to beam heating. Heating unirradiated samples to this temperature did not cause crystallization. The crystalline precipitates were identified as silicon using electron diffraction. The Si precipitates are thought to be initially present in unirradiated SiO and grow to an observable size during bombardment. The crystallization process followed nucleation and growth kinetics, and was found to saturate after .8% of the SiO had transformed to crystalline Si at a dose of 1.5 x 1022 ions/m2. (author)