Resistivity of ultrathin (0.6-3.7 nm) IrSi films on Si(100)

Ultrathin (0.6-3.7 nm) IrSi films are fabricated by electron beam evaporati on of iridium metal onto n-type silicon (100) substrates and subsequent sil icide formation at 500 degreesC. The sheet resistivity is measured at vario us temperatures in the range from 15 to 300 K. The polycrystalline c-IrSi f ilms which form fur a film thickness in excess of 8 nm show a metal-like be haviour of the resistivity. Ultrathin IrSi films of thickness less than 4 n m show an anomalous resistivity that increases with decreasing temperature. The exponential law observed for the resistivity is found to be consistent with hopping transport in amorphous IrSi predicted by the structure analys is for the thin films.