Optical and mechanical properties of transparent SrTiO₃ thin films deposited by ECR ion beam sputter deposition

Abstract

SrTiO 3 (STO) thin films have been deposited on glass substrates by electron cyclotron resonance (ECR) ion beam sputter deposition at different substrate temperatures (100-600 8C). The structural characteristics of the deposited films show a transition from amorphous phase to polycrystalline phase at 600 8C. The films exhibit good transparency with an interference pattern in the visible region and a very smooth surface without cracks. The refractive index of the films increases with an increase of the substrate temperature, and their dispersion was analyzed by a single-oscillator model. The extinction coefficient of the films in the visible region is of the order of 10 À3 -10 À2. The estimated values of the direct and indirect bandgap energies for the polycrystalline STO film are 3.80 and 3.32 eV, respectively. Its density is almost identical to the bulk STO single crystal, which is relatively high in comparison with those prepared by other techniques. The mechanical stability of the films is also improved with an increase of substrate temperature. Young's modulus and hardness of the polycrystalline STO film are 194.1 AE 15.5 and 22.5 AE 2.0 GPa, respectively.

Effect of CO2 Exposure on the Chemical Stability and Mechanical Properties of BaZrO3‐Ceramics

“…Finally, the reported hardness of materials reported in this study is in good agreement with the hardness reported for similar materials. [43][44][45][46][47][48][49][50] The fracture toughness of the conventionally sintered pristine materials does not have a systematic variation with regard to the grain size or the acceptor dopant level. It is…”

Growth and characterization of nanocrystalline SrTiOxfilms: room temperature deposition using RF sputtering system in a pure argon environment

“…An increase of surface roughness after the annealing process might be explained by the formation of the cluster like nano-grains. Furthermore, nanocrystal grain boundaries might be responsible from the formation of grain-boundary grooves, which significantly contributes to a rougher film surface [25][26][27]. As mentioned in our previous study, rms roughness in STO films deposited at 0.40 Pa with 0% O 2 flow rate is lower than 0.2 nm [28].…”

“…Absorption coefficients were calculated from k(λ) values (α(λ) = 4πk(λ)/λ). The optical band gap energy (E g ) was evaluated using Tauc formula [25]. The direct and indirect band gaps were determined from (αhv) 2 and (αhv) 1/2 versus hv, plots, respectively.…”

The enhancement of photocatalytic performance of SrTiO3 nanoparticles via combining with carbon quantum dots

“…11,15,17 The optical band gaps of the pure SrTiO 3 and CQD/ SrTiO 3 nanocomposite can be estimated via the formula (ahn) n ¼ A(hn À E g ), where a, h, n, E g , and A are the absorption coef-cient, Planck constant, light frequency, band gap, and a constant, respectively, and n is an exponent determined by the nature of the electron transition during the absorption process (n ¼ 2 for allowed direct transition and n ¼ 1/2 for allowed indirect transition). 19,44,45 Fig. 5b shows a curve of (ahn) 2 versus hn from which the band gaps of SrTiO 3 and CQD/SrTiO 3 were estimated to be 3.16 and 3.15 eV, respectively.…”