Dielectric response of polycrystalline Sr1−1.5xBixTiO3 thin films under direct current bias

Abstract

The effect of dc electric field Edc on the dielectric behavior of sol-gel derived Sr1−1.5xBixTiO3 films on Si/SiO2/TiO2/Pt substrates is systematically studied between 10 and 300 K. The rounded peak in the temperature dependence of the dielectric constant ε′(T) of all Sr1−1.5xBixTiO3 films is strongly suppressed under dc bias. The observed dielectric behavior is attributed to the formation of polar dipoles by the introduction of Bi into Sr site. A high tunability (∼40%) and communication quality factor (∼10 000) under 100 kV/cm make moderately Bi-doped SrTiO3 films a promising material for tunable devices.

Magnetic Anomaly and Dielectric Tunability of (Sr,Mn)TiO3Thin Films

“…3b. In contrast to the non hysteretic behaviour observed for undoped SrTiO 3 films [8], the corresponding curves of Sr 0.98 Mn 0.02 TiO 3 films exhibit "butterfly"-like form, being evidently hysteretic at 10 and 40 K and slightly hysteretic around 100 K. Figure 4 depicts a temperature dependence of the real part of the dielectric permittivity ε and dissipation factor, tanδ of Sr 0.98 Mn 0.02 TiO 3 films under 0, 50, and 100 kV/cm dc bias fields E dc , deduced from ε (E dc ) and tanδ(E dc ) dependences, respectively. Peak values of tanδ are below 1.5% and decrease with increasing dc bias.…”

“…5a, the relative tunability as a function of temperature under a maximum electric field of 100 kV/cm reaches up to ∼47.5%. The values of the relative tunability of Sr 0.98 Mn 0.02 TiO 3 films are higher than those of undoped SrTiO 3 films at similar temperatures [8].…”

Effect of charge compensation on the photoelectrochemical properties of Ho-doped SrTiO3 films

“…It can be seen that the dielectric properties of all the films have a similar trend as compared to the results of photocurrent density. At 1 kHz, the dielectric constant for the pure STO film is about 220, 36 while the dielectric constants of the STO-V Ti and the STO-e films are higher. Again, the dielectric constant of STO-V Sr films is the lowest among all the samples.…”

Electric-Field Tunability of Dielectric in Polycrystalline Sr 1- x Mn x TiO 3 Thin Films

“…[1,5,7] Although high quality BST epitaxial thin films can obtain considerable tunability and low loss simultaneously at room temperature, they must be fabricated by more sophisticated and costly methods such as molecular beam epitaxy, which is uneconomical. [6] On the contrary, the polycrystalline Sr 1−1.5𝑥 Bi 𝑥 TiO 3 thin films prepared by the simple and low-cost sol-gel method present a high value of relative tunability (∼40%) in the temperature range 55-86 K. [8] Furthermore, Kholkin et al reported that the temperature range of dielectric constant tunability is expanded to 150 K for Sr 1−𝑥 Mn 𝑥 TiO 3 ceramics compared with undoped STO by the introduction of Mn into the Sr site, and the maximum relative tunability can reach about 66% at 60 K. [11] However, the maximum value of tunability at lower temperature and the high applied voltage needed in SMTO ceramic [11] may limit their applications. As is well known, the thin film is an important material for the electronic device, while no work of electric tunability is reported on Sr 1−𝑥 Mn 𝑥 TiO 3 thin films yet.…”

“…The observed tunable results mentioned above in the SMTO thin films indicate: (i) The introduction of Mn into the Sr site in the thin film can make the temperature range of electric fieldtunable properties larger and can obtain the higher tunability values compared with those in undoped STO thin films, which is similar to the work in SMTO ceramics. [8,11,17] (ii) Compared with the tunable property in Sr 1−𝑥 Mn 𝑥 TiO 3 ceramics, [11] the highest tunability appears at 60 K, a high tunability (∼31.2%) can be obtained even at 150 K in the SMTO thin film. (iii) The high tunability can be comparable with that of ferroelectric thin films such as ∼30.74% at room temperature for ferroelectric Ba 0.6 Sr 0.4 TiO 3 films reported by Zhai et al [7] and the maximum value is ∼30% at 150 K for Sr 1−1.5𝑥 Bi 𝑥 TiO 3 films with 𝑥 = 0.0133 as claimed by Okhay et al [8] - The origin of the high tunability of Mn-doped STO has been well discussed by Kholkin et al [11,18] They proposed that the tunable behavior of SMTO ceramics is due to the polar dipoles induced by the off-center position of Mn 2+ at the Sr site and the decrease of 𝜀 with the dc bias field can be explained by the stabilization of the local potential wells for the off-center Mn 2+ dipoles under applied external electric fields, [11] which is in good accordance with our situation in the SMTO thin film.…”