Formation of the CeSix/Si(111) interface

The deposition of thin Ce films on Si(111) and subsequent or simultaneous annealing leads to the formation of various structurally, electronically, and chemically different CeSix phases, as revealed by scanning-tunneling microscopy, low-energy electron diffraction, and photoelectron spectroscopy. Several phases can coexist on the same sample, and with increasing annealing temperatures larger homogeneous domains are observed. This behavior is assigned to a mismatch of the lattices of the Si-rich CeSix bulk compounds with that of the Si(111) substrate surface, resulting at temperatures above 700 °C in the formation of a thin film of hexagonal CeSi1.67, which does not exist as a bulk compound.