Properties of iron silicide contacts to n- and p-type silicon

Abstract

Thin polycrystalline films of FeSi and β-FeSi2 were formed by solid state reaction with either boron or phosphorus doped silicon. The corresponding electrical heterojunction properties were studied by temperature activated current-voltage and capacitance-voltage analysis. The FeSi/Si Schottky characteristics showed that the current transport mechanism was dominated by thermionic emission across the interfaces for both n- and p-type silicon substrates. Indications of recombination through deep levels was only detected for n-type silicon measured by current-voltage at low temperatures. The Schottky barrier heights of FeSi were estimated to 0.68 ± 0.03 eV and 0.40 ± 0.03 eV at 0K for respectively n- and p-type silicon. The Schottky barrier was observed to be pinned to the silicon valence band. The formation of β-FeSi2 produced current transport characteristics with ideality factors of about 1.02-1.05 on both n- and p-type silicon indicating no recombination through deep levels inside the silicon depletion layer. The CV results on p-type silicon strongly showed the presence of shallow defects or neutral complex formation.