Interface structure and lattice mismatch of epitaxial CoSi2 on Si(111)

Abstract

We have used the x-ray standing-wave technique and bulk x-ray diffraction to investigate the structural properties of thin CoSi2 layers grown epitaxially on Si(111). The perpendicular lattice mismatch with respect to the Si substrate was found to be −0.0152±0.0003 and −0.016±0.001 for 6-nm-thick and 16-nm-thick layers, respectively. The distance between Si(111) and the first Co layer was measured to be (0.288±0.005) nm and is thus stretched by (0.014±0.005) nm compared with a value determined by Si-like bulk bond length. The Co atoms are attached to the Si(111) dangling bonds in agreement with the model of fivefold coordinated metal atoms at the interface.