Optical studies of phosphorus-doped poly-Si films

Abstract

We have performed a detailed optical study of phosphorus-doped polycrystalline silicon films (prepared by amorphous deposition with in situ doping and annealing by thermal oxidation up to 1000°C) using Raman spectroscopy and variable-angle spectroscopic ellipsometry from 0.7 to 5 eV. We focus on the determination of strain and grain size using optical techniques and compare with results of a structural analysis using plan-view transmission electron microscopy and atomic force microscopy. We analyze the derivatives of our ellipsometry data (peak shifts and broadenings) using analytical lineshapes,which are affected by grain size, film thickness, doping, and inhomogeneity, but only minimally by macroscopic biaxial strain.