Very high commutation quality factor and dielectric tunability in nanocomposite SrTiO₃ thin films with T_c enhanced to >300 °C

Abstract

We report on nanoengineered SrTiO3–Sm2O3 nanocomposite thin films with the highest reported values of commutation quality factor (CQF or K-factor) of >2800 in SrTiO3 at room temperature.

Metal Oxide Nanocomposites: A Perspective from Strain, Defect, and Interface

“…A high and stable dielectric tunability (75% at 200 kV cm −1 ) and low dielectric loss values (tan δ < 0.01) were achieved at room temperature . In an STO:Sm 2 O 3 VAN, large dielectric constant tunability (49%), low tangent loss, high commutation quality factor (>2800) were reported in the SrTiO 3 phase . The large vertical tensile strain was attributed to the enhanced dielectric properties in BSTO and STO.…”

“…It was found that the out‐of‐plane and in‐plane lattice parameters are 4.06 and 3.98 Å, respectively, indicating an out‐of‐plane tensile strain of 0.6% . Sangle et al synthesized STO:Sm 2 O 3 VANs with high tetragonality ( c / a ) (up to 1.023) in the STO phase . Owing to the large out‐of‐plane tensile strain, a T C up to 300 °C was observed in STO.…”

Defects in complex oxide thin films for electronics and energy applications: challenges and opportunities

“…127 A very low dielectric loss (tan d B 0.01) and relative large dielectric tunability (49% at 400 kV cm À1 ) was further reported in SrTiO 3 :Sm 2 O 3 VAN film. 128 Yang et al explored BiFeO 3 :Sm 2 O 3 VAN films and found that dielectric loss and leakage current were reduced compared to plain BiFeO 3 films (Fig. 5c).…”

Columnar Nanograined BaTiO3 Ferroelectric Thin Films Integrated on Si with a Sizable Dielectric Tunability

“…BaTiO3 基薄膜具有优异的铁电、介电和压电等 性能，可广泛应用于介电调谐器件、移相器、介电 电容器、存储器、能量收集器等电子器件中 [1][2][3][4][5] 。本 研究着重为介电调谐器件提供研究思路，该类器件 需要尽可能高的介电调谐率和尽可能低的介电损耗， 从而保证器件的高调谐范围、高品质因子(Figure of Merit, FOM)以及高信号传输效率 [6][7][8][9] 。因此，提高介 电调谐率并降低介电损耗成为其相关研究的重点。 介电损耗是制约介电调谐器件 应用的重要因素，降低介电损耗是提高调谐效 率的关键。通过两步放电等离子烧结制备晶粒取向 的钙钛矿陶瓷，然后通过设计层状结构使其产生位 错堆垛，能有效地消除陶瓷内部的氧空位，极大提 高其介电调谐率并有效地控制介电损耗 [10] 。另外， 也可通过对钙钛矿陶瓷进行掺杂，使其处于多相共 存的状态， 易于形成多重极化， 从而使材料在铁电、 介电等性能方面达到综合最优 [11][12] 。 近年来，包括介电调谐器件在内的电子元器件 趋向于小型化和集成化。提高薄膜材料的介电调谐 率和品质因子已经成为研究的重点。山东大学张伟 等 [6] 用磁控溅射法在 SrTiO3 基底上 700 ℃制备出了 不同晶体取向的外延 BaTiO3 铁电薄膜，当外延 BaTiO3 铁电薄膜取向为(110)时，介电调谐率和介电 损耗均达到最大值。 剑桥大学 SANGLE 等 [13] 通过对 顺电相的 SrTiO3 进行掺杂，在 SrTiO3 基底上 750 ℃ 制备出了高四方度的 SrTiO3-Sm2O3 纳米复合薄膜， 该薄膜有着优异的介电调谐率和品质因子。山东大 学 郝 兰 霞 等 [14] [17] 。此外，在硅上的低温溅射，又使得 BaTiO3 薄膜产生了面内的压缩应变 [17] 。结合这些结果，本 研究在低制备温度下在硅基底上获得了柱状纳米晶 [18] [17,20] [17,21] 。因此，500 ℃ 制备的 BaTiO3 薄膜晶粒尺寸较大。而 450 ℃对应 着较高的 "过冷度" ， 晶粒的形核速率高于长大速率， 所以薄膜由数量较多的小晶粒组成 [17] [17] ，即 m = S + 0 ε r…”