Frustrated dimers at the CoSi2/Si(001) interface

The interface between epitaxial CoSi2 and Si(001) has been investigated with medium-energy ion scattering. Ions are sharply dechanneled at the interface, due to an interfacial layer of reconstructed silicon. Both the intensity and angular distribution of the interface peak closely match simulations for a dimer reconstruction. The results are incompatible with models of the interface that do not include substantial displacement of silicon atoms, such as a pure composition modulation. The bond length of 2.6±0.1 is significantly longer than found at the Si(001) surface, due to the repulsive interactions with coplanar, nondimerized Si atoms. © 1993 The American Physical Society.