Optical conductivity of Ni_1-xPt_xSi monosilicides (0 < x < 0.3) from spectroscopic ellipsometry

The optical constants of 22 nm thick Ni1-xPtxSi (0 < x < 0.3) monosilicide films were measured using spectroscopic ellipsometry, in the spectral range from 0.6 to 6.6 eV at room temperature. Ni1-xPtx films sputtered on clean Si were annealed at 500 °C for 30 s to form nickel platinum monosilicides. The correct silicide thickness was found by minimizing Si substrate artifacts in the optical constants of Ni1-xPtxSi determined from ellipsometric data analysis. Two interband transitions at 1.8 and 4.5 eV were observed (rather than three peaks in PtSi). The absorption peak at 4.5 eV broadens with increasing Pt content in the monosilicide.