A study was made of the incorporation of heavily supersaturated C, using the solid-phase epitaxy of implanted amorphous layers. The strain in the Si1-xCx/Si heterostructures was measured by using rocking-curve X-ray diffraction measurements. The introduction of defects was monitored by using ion channelling and transmission electron microscopy. The fraction of C which was located at substitutional lattice sites was monitored by using Fourier transform infra-red absorption spectroscopy and ion channelling at resonance energies. The C depth profiles were monitored by means of secondary ion mass spectroscopy. The metastable solubility limit for the incorporation of C by solid-phase epitaxy was found to be between 3 x 1020 and 7 x 1020/cm3. This was more than 3 orders of magnitude above the equilibrium solubility at the melting point of Si. This limit was set by the ability to re-grow without introducing micro-twins and stacking faults along {111} planes. It was postulated that the local bond deformation which resulted from the atomic size difference between C and Si led to faceting of the amorphous/crystalline interface and led to the introduction of defects; thus limiting the supersaturations which could be achieved by means of solid-phase epitaxy. It was also found that the defect density in the re-grown alloys could be reduced by using higher solid-phase epitaxial re-growth temperatures during rapid thermal annealing.

J.W.Strane, S.R.Lee, H.J.Stein, S.T.Picraux, J.K.Watanabe, J.W.Mayer: Journal of Applied Physics, 1996, 79[2], 637-46