Effect of O2/Ar flow ratio and post-deposition annealing on the structural, optical and electrical characteristics of SrTiO3 thin films deposited by RF sputtering at room temperature

Abstract

Effect of O 2 /Ar flow ratio and post-deposition annealing on the structural, optical and electrical characteristics of SrTiO 3 thin films deposited by RF sputtering at room temperature, Thin Solid Films (2015), SrTiO 3 (STO) thin films have been prepared by reactive rf magnetron sputtering on Si (100) and UV fused silica substrates at room temperature. The effect of oxygen flow on film characteristics was investigated at a total gas flow of 30 sccm, for various O 2 /O 2 +Ar flow rate ratios. As-deposited films were annealed at 700 °C in oxygen atmosphere for 1 h. Postdeposition annealing improved both film crystallinity and spectral transmittance. Film microstructure, along with optical and electrical properties were evaluated for both asdeposited and annealed films. Abroad photoluminescence emission was observed with in the spectral range of 2.75-3.50 eV for all STO thin films irrespective of their deposition parameters. Upon annealing, the optical band gap of the film deposited with 0% O 2 concentration slightly blue-shifted, while the other samples grown at higher oxygen partial pressure did not show any shift. Refractive indices (n) (at 550 nm) were in the range of 2.05 to 2.09, and 2.10 to 2.12 for as-deposited and annealed films, respectively. Dielectric constant values (at 100 kHz) within the range of 30-66 were obtained for film thicknesses less than 300 nm, which decreased to~30-38 after post-deposition annealing.

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

“…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]. We observe that increase in surface roughness under high deposition pressure.…”

“…The direct (indirect) band gap energies of the as-deposited and annealed films are found to be 2.44 (2.88) eV, and 2.57 (2.88) eV in figure 5(a) and 5(b), respectively. Direct and indirect band gap values are lower than the noted values in our previous study for 0.40 Pa deposition pressure [28]. The reduction in band gap energies might be due to the variation in the oxidation state of the film and stoichiometric changes with increasing deposition pressure up to 0.67 Pa.…”

“…Furthermore, in the VIS range, the refractive indices of nanocrystalline STO films are found to be 2.36 and 2.31 (@550 nm) for as-deposited and annealed films, respectively. Its value decreased with annealing, however, the observed values is larger than the reported amorphous (1.83-2.06) and polycrystalline (2.05-2.12) films [28,[32][33][34]. It should be noted that the film thickness which is generally lower than 100 nm has affects film properties, however, according to our best knowledge there is no comparative information on the effect of film thickness on thin STO films.…”

Preparation of (110)‐oriented SrTiO3 film on quartz glass by laser chemical vapor deposition

“…Various methods had been developed to prepare STO film such as radio frequency sputtering, spray inductively coupled plasma technique, pulsed laser deposition, molecular beam epitaxy, sol‐gel, electron cyclotron resonance ion beam sputter deposition, metal‐organic chemical vapor deposition (MOCVD), and laser chemical vapor deposition (laser CVD) . Among these techniques, the laser CVD was considered as a more promising approach due to its high deposition rate ( R dep ) and excellent control of film orientation .…”

Microestrutura e propriedades elétricas e dielétricas do titanato de estrôncio puro e contendo aditivos

“…Muitos estudos sobre as propriedades do SrTiO 3 estão sendo realizados, tais como em propriedades: termoelétricas [27], ópticas [28], ferroelétricas [29] e elétricas [11].…”