Tuning of the stop-band position in the visible range of SiO2/TiO2 Bragg reflectors by doping TiO2 with transition metals

Abstract

Within this paper, the influence of the doped-TiO2 layer with Cu, Ni, Co and Cr on the stop-band position of SiO2/TiO2 Bragg reflectors was investigated. The films crystallize into pure anatase phase whatever is the element of doping. As the atomic radius of the elements of doping raises (rCu<rNi<rCo<rCr) the grain size decreases (DCu<DNi<DCo<DCr). In UV–Vis-NIR analyses, width (w), transmission coefficient (T%) and position (λ) of the stop-band have been tuned. Under the effect of doping, the stop-band shifts from 406 nm to 699 nm covering, thus, the totality of the visible spectral range.