Investigations about the effect of annealing temperatures in the presence of oxygen flow on optical and electronic properties of titanium nano-layers by using Kramers–Kronig and DFT methods

Nano-layers of titanium were deposited on glass substrates by resistive evaporation at room temperature. Thickness of the layers was measured 66.8 nm, by a quartz crystal method. Deposition conditions such as deposition rate, vacuum pressure, incidence of angle and substrate temperature were the same for all layers. After producing pure Ti layers a post-annealing method was used in the presence of a uniform oxygen flow of 6 cm3/s and different 100 °C, 200 °C and 300 °C annealing temperatures. Optical reflectance and transmittance of the layers were measured in the wave length of 200–4100 nm by a spectrophotometer. Kramers–Kronig relations were used to calculate the optical constants. The influence of annealing temperature and oxygen flow on optical properties is investigated. Also to make the obtained optical results clearer, a full-potential linearized augmented plane wave (FP-LAPW) method within the generalized gradient approximation (GGA) has been used. Comparison results confirm that in higher annealing temperatures the obtained structure is more similar to anatase crystalline one. According to AFM images, by increasing annealing temperature in the presence of oxygen flow, configuration of layers change and due to high annealing temperature and surface diffusion effect, void fraction increases. With increase in annealing temperature to 300 °C, anatase phase structure (A(004)) gets clearer and sharper also other phase structures are about to grow.