Stacking fault structures in carbon-contaminated low-temperature epitaxial silicon

Stacking fault structures have been observed by transmission electron microscopy in {111} epitaxial Si layers grown from silane contaminated with trace amounts of ethylene. The type of fault structure depended upon the growth temperature: at low temperatures (830 to 940 °C) ribbon faults bounded by Shockley partial dislocation loops were found but at higher temperatures these gave way to configurations such as stacking fault tetrahedra. It is proposed that the fault structures are nucleated by carbon contamination during epitaxial growth and the difference in structure with temperature is interpreted by changes in the way carbon is incorporated in the layer. The presence of Shockley loops suggests a simple meachanism for the formation of stacking fault tetrahedra by the intersection of three loops on adjacent inclined {111} planes.