Optical Characterization of PtSi/Si by Spectroscopic Ellipsometry

TL;DR

This study uses spectroscopic ellipsometry to nondestructively analyze the optical properties and composition of PtSi films on silicon, providing insights into their electronic structure and confirming layer formation with microscopy techniques.

Contribution

First application of spectroscopic ellipsometry to characterize PtSi/Si films, revealing composition, electronic transitions, and layer formation in a nondestructive manner.

Findings

PtSi monolayer has a 1:1 Pt:Si ratio

Detected electronic transitions in Pt 5d states

Confirmed layer formation with microscopy

Abstract

We report optical characterization of PtSi films for thermoelectric device applications by nondestructive spectroscopic ellipsometry (SE). Pt monolayer and Pt-Si multilayer which consists of 3 pairs of Pt and Si layers were deposited on p-doped-silicon substrates by sputtering method and then rapid annealing process was done to form PtSi films through intermixing of Pt and Si atoms at the interface. Pseudodielectric function data <{\epsilon}> = <{\epsilon}1> + i<{\epsilon}2> of the PtSi/Si samples were obtained from 1.12 to 6.52 eV by using spectroscopic ellipsometry. Employing Tauc-Lorentz and Drude models, the dielectric function ({\epsilon}) of PtSi films were determined. We found that the composition ratio of Pt:Si is nearly 1:1 for PtSi monolayer and we observed transitions between occupied and unoccupied states in Pt 5d states. We also observed formation of PtSi layers in Pt-Si multilayer sample. The SE results were confirmed by the transmission electron microscopy and energy dispersive X-ray spectroscopy.