Optical properties of RF sputtered strontium substituted barium titanate thin films

Leite

Journal of Applied Physics

et al. 2002

Barium strontium titanate ͑Ba 0.8 Sr 0.2 TiO 3 ͒ thin films have been prepared on Pt/Ti/SiO 2 /Si substrates using a soft solution processing. X-ray diffraction and also micro-Raman spectroscopy showed that the Ba 0.8 Sr 0.2 TiO 3 thin films exhibited a tetragonal structure at room temperature. The presence of Raman active modes was clearly shown at the 299 and 725 cm Ϫ1 peaks. The tetragonal-to-cubic phase transition in the Ba 0.8 Sr 0.2 TiO 3 thin films is broadened, and suppressed at about 35°C, with a maximum dielectric constant of 948 ͑100 kHz͒. Electrical measurements for the prepared Ba 0.8 Sr 0.2 TiO 3 thin films showed a remnant polarization ͑P r ͒ of 6.5 C/cm 2 , a coercive field ͑E c ͒ of 41 kV/cm, and good insulating properties. The dispersion of the refractive index is interpreted in terms of a single electronic oscillator at 6.97 eV. The direct band gap energy ͑E g ͒ and the refractive index ͑n͒ are estimated to be 3.3 eV and n ϭ 2.27-2.10, respectively.

Section: Resultssupporting

confidence: 87%

“…29 Similar results have been observed in BST films prepared by other techniques. 30,31 Therefore, the dispersion of the refractive index can be described by the Sellmeier dispersion formula…”

Section: Resultsmentioning

confidence: 99%

Ferroelectric and optical properties of Ba0.8Sr0.2TiO3 thin film

Leite

Journal of Applied Physics

et al. 2002

Journal of Nanomaterials

“…The sigmoidal dependence of the band gap with composition is evident. The tendency in the band gap values for BST-SS agrees with those reported in literature [2,6,30,31]. Figure 8 presents the evolution of deposition rate, calculated from the film thickness and the sputter time, with respect to (a) the RF-magnetron power and (b) the parameter in the Ba x Sr 1−x TiO 3 solid solution.…”

Section: Resultssupporting

confidence: 86%

Stoichiometry Calculation in Ba_xSr_1−xTiO₃ Solid Solution Thin Films, Prepared by RF Cosputtering, Using X-Ray Diffraction Peak Positions and Boltzmann Sigmoidal Modelling

Reséndiz-Muñoz

Fernández-Muñoz

Corona-Rivera

et al. 2017

A novel procedure based on the use of the Boltzmann equation to model the parameter, the film deposition rate, and the optical band gap of Ba x Sr 1−x TiO 3 thin films is proposed. The Ba x Sr 1−x TiO 3 films were prepared by RF cosputtering from BaTiO 3 and SrTiO 3 targets changing the power applied to each magnetron to obtain different Ba/Sr contents. The method to calculate consisted of fitting the angular shift of (110), (111), and (211) diffraction peaks observed as the density of substitutional Ba 2+ increases in the solid solution when the applied RF power increases, followed by a scale transformation from applied power to parameter using the Boltzmann equation. The Ba/Sr ratio was obtained from X-ray energy dispersive spectroscopy; the comparison with the X-ray diffraction derived composition shows a remarkable coincidence while the discrepancies offer a valuable diagnosis on the sputtering flux and phase composition. The proposed method allows a quick setup of the RF cosputtering system to control film composition providing a versatile tool to optimization of the process.

“…Another possible reason for larger values of Eg in the amorphous phase is the existence of the density of states as explained by Davis and Mott [18]. The Eg values of this research work and the bibliography of Table 3 were found above some reported [22,23,24].…”

Section: Preprints (Wwwpreprintsorg) | Not Peer-reviewed | Postedsupporting

confidence: 62%

Set-Up Method on Properties of BaXSr1-XTiO3 Thin Films Deposited by RF-Magnetron Co-Sputtering by Projecting Temperature and Stoichiometric Effect

Estrada-Martínez¹,

Melo-Banda²,

Páramo-García³

et al. 2017

Preprint

Thin films (100-400 nm) of BaxSr1-xTiO3 (0≤x≤1) deposited in RF-magnetron co-sputtering equipment are presented in this research work. The change of deposition rate, gap energy, and resistivity as a function of temperature-applied power change in the growth parameters was studied through the ISO colour-code lines constructed with MATLAB:By analysing the trend information and take into account the influence of the calculated "x" parameter with the Boltzmann profile fitting is proposed a method to allow a controlled set up of the RFmagnetron co-sputtering system and predict the Eg and resistivity values in the BaxSr1-xTiO3 solid solution with 0≤x≤1 for amorphous and crystalline phases. Also, a versatile tool to optimise the deposition process and material properties.keywords: BaxSr1-xTiO3 films; boltzmann modelling; optical band gap; deposition rate; stoichiometric content Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: