Antiphase boundaries as nucleation centers in low-temperature silicon epitaxial growth

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Abstract
The epitaxial growth of silicon on Si(001) from disilane at 720 K has been investigated using scanning tunneling microscopy. Epitaxy occurs by island nucleation and growth, with islands nucleating preferentially at antiphase boundaries between different regions on the substrate terraces. These islands begin as a single dimer string which grows to cover the entire antiphase boundary before lateral growth begins. The islands increase in size until they meet on the surface, forming new antiphase boundaries (50% of the time) for nucleation of the next layer. We find that islands nucleated at such boundaries account for approximately 94% of the area of a growing layer, indicating that essentially all epitaxial growth at this temperature occurs by this mechanism.