Institut d’Electronique de Microelectronique et de Nanotechnologie (IEMN), Departement Opto-Acousto-Electronique (DOA E), Villeneuve d’Ascq, France.
IEEE Trans Ultrason Ferroelectr Freq Control. 2013 May;60(5):880-7. doi: 10.1109/TUFFC.2013.2645.
A complete microwave characterization up to 67 GHz using specific coplanar waveguides was performed to determine the dielectric properties (permittivity, losses, and tunability) of sapphire/TiOx/Ba0.3Sr0.7TiO3 (BST) (111)-oriented thin films. To that end, BaxSr1-xTiO3 thin films were deposited by RF magnetron sputtering on sapphire (0001) substrate. To control the preferred (111) orientation, a TiOx buffer layer was deposited on sapphire. According to the detailed knowledge of the material properties, it has been possible to conceive, fabricate, and test interdigitated capacitors, the basic element for future microwave tunable applications. Retention of capacitive behavior up to 67 GHz and a tunability of 32% at 67 GHz at an applied voltage of 30 V (150 kV/cm) were observed. The Q-factor remains greater than 30 over the entire frequency band. The possibility of a complete characterization of the material for the realization of high-performance interdigitated capacitors opens the door to microwave device fabrication.
采用特定共面波导对 67GHz 以下的微波特性进行了全面表征，以确定蓝宝石/TiOx/Ba0.3Sr0.7TiO3（BST）（111）取向薄膜的介电性能（介电常数、损耗和可调谐性）。为此，通过射频磁控溅射在蓝宝石（0001）衬底上沉积了 BaxSr1-xTiO3 薄膜。为了控制优选的（111）取向，在蓝宝石上沉积了 TiOx 缓冲层。根据对材料性能的详细了解，已经可以设计、制造和测试叉指电容器，这是未来微波可调谐应用的基本元件。在 30V（150kV/cm）的外加电压下，在 67GHz 时观察到保持电容行为和 32%的调谐性。在整个频带内，Q 因子都大于 30。为了实现高性能叉指电容器，对材料进行全面表征的可能性为微波器件制造开辟了道路。
