Enhanced surface/interface recombination and surface inversion of Ni decorated Si/Si(Ge)/Si heterostructures

Electron beam induced current variations in images of strain relaxed epitaxial Si/Si(Ge)/Si wafers deliberately contaminated with nickel from the backside are reported for different contamination levels. Strong recombination contrast due to NiSi2 precipitates was observed both at the top Si surface and along buried interfacial misfit dislocations. A surface conductivity inversion from n to p type was obtained for the high level Ni contaminated sample. A theoretical analysis based on the presence of a surface potential due either to a metal-silicon Schottky contact, or to the accumulation of charged traps is used to explain the observed effects.