Transition-metal contacts to atomically clean silicon

Abstract

Atomically clean silicon surfaces have been produced by cleaving n-type silicon single crystals on a (111) plane in UHV conditions, and their workfunction has been measured. Transition metals of the 3d and 5d series have been evaporated on these surfaces and their workfunctions as well as the barrier heights of the resulting intimate metal-silicon contacts have also been measured without breaking the ultra-high vacuum. No simple relationship of the type predicted by the Schottky theory exists between barrier heights and metal workfunctions, and in the case of the sequence Fe-Co-Ni the barrier height actually decreases as the workfunction increases.