Atomic structure and electronic states of nickel and copper silicides in silicon

This paper summarizes current understanding of structural and electronic properties of nickel and copper silicide precipitates in silicon. From high-resolution electron microscopy studies it has been concluded that metastable structures form during early stages of precipitation which transform into energetically more favourable configurations during additional annealing or slow cooling. These structural transformations are related to changes of the electronic structure of the precipitates as revealed by deep level transient spectroscopy (DLTS) and electron beam induced current (EBIC). Deep bandlike states at initially formed NiSi2- and Cu3Si-platelets detected by DLTS have been attributed to a bounding dislocation and precipitate/matrix interfaces, respectively. Large NiSi2-precipitates act as internal Schottky barriers and may control the minority carrier lifetime of silicon samples. Recent advances in modeling EBIC contrasts provide insight how metal impurities affect the electrical behaviour of dislocations at different degrees of decoration.