Physical Properties of Hole-Doped Rutile TiO2 using Virtual Crystal Approximation

Abstract

Titania (TiO₂) is a structurally stable multi-functional material having the semiconducting features suitable for optoelectronic applications. By using virtual crystal approximation (GGA + mBJ) in DFT method, the pristine rutile TiO₂ has the direct band gap of 2.35 eV with non-magnetic semiconducting nature. It is active in visible as well as near-UV ranges. Furthermore, this pristine structure has the static refractive indices 2.16 (xx) and 2.37 (zz), while the dielectric constants 4.6 (xx) and 5.6 (zz-direction). Above 5.3 eV, the dielectric function is observed to have the negative real part, indicating plasmonic behavior. When considering hole-doping in rutile TiO₂ to the Ti-site, the dielectric constant has higher value. When doping concentration increases from 10% to 20%, the optical band gap changes from 3.10 eV to 3.61 eV. This shift is mainly due to interband transitions between O(2p) and Ti(3d) states. The obtained results show that the hole-doped rutile TiO₂ can be the potential candidate for the optoelectronic applications.