IEEE Trans Ultrason Ferroelectr Freq Control. 2022 Apr;69(4):1461-1468. doi: 10.1109/TUFFC.2022.3145496. Epub 2022 Mar 30.
High-temperature (HT) properties of a thickness-shear mode (TSM) langasite resonator with Ru-Ti electrodes are reported for the first time. Resonators with 300 nm Ru and 15 nm Ti films as the primary and adhesive electrode layers, respectively, were investigated and compared against those with Au-Cr and Au-Ti electrodes. HT stability of the fabricated samples under continuous excitation were examined up to 750 °C by monitoring their morphological changes, sheet resistance, resonance parameters, and their equivalent circuit elements. Results indicate that for Ru-Ti electrodes, a polycrystalline RuO cover layer was formed on the surface of Ru, which protected the underlying layer from further oxidation. Consequently, the electrical and motional resistances of the Ru-Ti sample experienced the least change post-annealing, which was also reflected in its ability to retain the highest Q -factor after heat treatment. Ru-Ti-based resonator also exhibited comparable performance to other samples in terms of resonant frequency shifts and second-order temperature coefficients, further strengthening the position of Ru as a suitable alternative to other electrode materials.
首次报道了具有 Ru-Ti 电极的厚度剪切模式（TSM）拉曼斯石谐振器的高温（HT）性能。研究了分别具有 300nm Ru 和 15nm Ti 薄膜作为主要和粘附电极层的谐振器，并与具有 Au-Cr 和 Au-Ti 电极的谐振器进行了比较。通过监测其形貌变化、薄膜电阻、谐振参数及其等效电路元件，在连续激励下检查了所制备样品在高达 750°C 的 HT 稳定性。结果表明，对于 Ru-Ti 电极，在 Ru 的表面形成了多晶 RuO 覆盖层，从而保护了下面的层免受进一步氧化。因此，Ru-Ti 样品的电和动电阻在退火后经历了最小的变化，这也反映在其在热处理后保持最高 Q 因子的能力上。在谐振频率偏移和二阶温度系数方面，基于 Ru-Ti 的谐振器与其他样品具有相当的性能，进一步巩固了 Ru 作为其他电极材料的合适替代品的地位。
