Investigation of the Properties of Ca-doped TiO2 Thin Films Formed by e-beam Evaporation

Abstract

Titanium dioxide is considered as one of the most important materials due to its unique dielectric, electrochemical, photocatalytic and optical properties. These properties can be altered by introducing particular amount of dopants. In this work, Ca-doped titanium dioxide was formed by electron beam deposition method and the structural and electrical properties were investigated. For the evaluation of the structural properties the formed thin ceramic films were studied by X-ray diffraction (XRD), energy dispersive spectrometry (EDS) and scanning electron microscopy (SEM). Electrical properties were investigated by impedance spectroscopy. It was found that when the concentration of Ca dopants increases the crystallites size increases as well and follows Vegard's law. The impedance measurements show that the Ca-doping decreased the total conductivity of the formed thin films. The total conductivity varies from 2.7 S/cm in pure TiO 2 to 4 × 10 -4 S/cm in 2.5 % Ca doped TiO 2 at 800 °C under wet reducing conditions and from 5.4 × 10 -4 S/cm in pure TiO 2 to 3.4 × 10 -5 S/cm in 0.5 % Ca doped TiO 2 at 800 °C under wet oxidizing conditions.

Effects of Thermally Induced Phase Transition on the Negative Thermo-Optic Properties of Atomic-Layer-Deposited TiO2Films

“…Porosity is a property that is directly related to a material density. To identify the influence of porosity on the refractive index, the porosity of the as-deposited and annealed TiO 2 films was calculated using the equation below , where d is the density of bulk anatase TiO 2 (3.78 g·cm –3 ) and d p is the density of porous thin films. In Figure c, it should be noted that porosity considerably decreases after annealing: the porosity of as-deposited TiO 2 is 6.6%, decreases to 5.3% after annealing at 300 °C, and is further reduced down to 2.1% after annealing at 600 °C.…”

“…where d is the density of bulk anatase TiO 2 (3.78 g•cm −3 ) 48 and d p is the density of porous thin films. In Figure 4c, it should be noted that porosity considerably decreases after annealing: the porosity of as-deposited TiO 2 is 6.6%, decreases to 5.3% after annealing at 300 °C, and is further reduced down to 2.1% after annealing at 600 °C.…”

Performance Analysis of Calcium-Doped Titania (TiO2) as an Effective Electron Transport Layer (ETL) for Perovskite Solar Cells

“…Generally, high oxygen pressure favors the formation of the condensed and smooth layer during deposition, since the ablated particles with smaller size after collision with oxygen are advantageous to a homogeneous distribution of the nanostructured layer. This is also mainly due to the anatase in the degenerated phase transition coupled with the growth of the crystals, which leads to the process of external aggregation and coarsening [35]. Such anatase to rutile phase distribution has been widely reported to occur in doped TiO 2 films.…”

Structural Parameter Analysis of Mg Doped ZnO Nano Rods by Fuzzy Logic Controller

“…Several simulation tools that can be adopted to check and estimate the process parameters include COMSOL [30], ANSYS [31], TRNASYS [32], and MATLAB [33]. The FLC is a method to incorporate human-like reasoning in a control system.…”