Strong polaronic effects on rutile TiO2 electronic band edges

Abstract

Thin TiO2 films are prepared by dc magnetron sputtering as well as by the sol-gel technique, and the optical band edge absorption asvd is obtained from transmission spectroscopy. The electronic structure and optical properties are studied employing a first-principle linearized augmented plane-wave method within the local density approximation sLDAd, improved by an on-site Coulomb self-interaction potential sLDA+USICd. We show that the correction potential, the polaronic screening, and the spin-orbit interaction are crucial for determining the TiO2 effective electron and hole masses. The dielectric function «svd=«1svd+i«2svd and the high-frequency constant «s0!v!Eg /"d show pronounced anisotropy. The electron-optical phonon interaction affects «sv<0d strongly.