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The Synthesis and Stability of Si1−yQy Alloys and Strained Layer Superlattices
Published online by Cambridge University Press: 22 February 2011
Abstract
We have synthesized Si1−yQy layers and strained layer superlattices on Si (100) with C concentrations of up to a few percent using Solid Source Molecular Beam Epitaxy. The presence of C even in small quantities is known to disrupt the epitaxy of Si. We show that under conditions of high Si flux for a given C/Si flux ratio, defect-free epitaxy results. However, exceeding a critical C/Si flux ratio leads to disruption of epitaxy, initially via twinning and subsequently by amorphous growth. Growth temperature also plays a significant role in preventing twinning and islanding. Low growth temperature also suppresses the precipitation of β-SiC and leads to the formation of pseudomorphic Si1−yQy random alloys. The layers are characterized by X-ray diffraction, Secondary Ion Mass spectroscopy, and Transmission Electron Microscopy. We have also studied the thermal stability of strained layer superlattices and find that the layers are stable to about 800°C (for y = 0.003). Between 800°C and 1000°C, the layers relax by interdiffusion. Above 1000°C, silicon carbide precipitation occurs and the carbide layers nucleate and grow at high C content regions of the film.
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- Copyright © Materials Research Society 1991
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