The Co/Si(1 1 1) interface formation: a temperature dependent reaction

We have investigated the reaction of Co with the Si(1 1 1) surface both at room temperature (RT) and at high temperature (500–650 °C). The temperature evolution of the RT deposited 10 ML film has also been studied. The films, prepared by the different methods, have been structurally characterized by means of primary-beam diffraction modulated electron emission. Auger electron spectroscopy has been used to follow their stoichiometric evolution. For RT deposition the films have been found to have a B-type (180° rotated with respect to the underlying Si(1 1 1) surface) cubic structure with a Co content and an interlayer spacing increasing with thickness. After 650 °C annealing, the films are completely reacted and have an unstrained B-type CoSi2 structure. High temperature (500 °C) deposition of Co leads to the formation of stoichiometric CoSi2 films. Both annealed and high temperature grown films are found to be Si terminated.