Niu Miaomiao, Zhu Hanfei, Wang Yingying, Yan Jing, Chen Ning, Yan Peng, Ouyang Jun
Institute of Advanced Energy Materials and Chemistry, School of Chemistry and Chemical Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, China.
Key Laboratory for Liquid-Solid Structure Evolution and Processing of Materials (Ministry of Education), School of Materials Science and Engineering, Shandong University, Jinan 250061, China.
ACS Appl Mater Interfaces. 2020 Jul 29;12(30):33899-33907. doi: 10.1021/acsami.0c07155. Epub 2020 Jul 16.
As a prototype single-phase multiferroic, BiFeO exhibits excellent electrical, magnetic, and magnetoelectric properties, appealing to many modern technological applications. One of its overlooked merits is a high piezoelectric performance originating from its large remnant polarization () and low dielectric constant (ε). Furthermore, its high Curie temperature and large coercive field ensure good stabilities in device applications. However, to achieve close-to-intrinsic properties, a high processing temperature is usually used for the preparation of highly crystalline (epitaxial or highly oriented) BiFeO films. Proliferation of defects due to loss of volatile BiO in the high-temperature process and its incompatibility with CMOS-Si technologies have hindered the development of BiFeO film-based piezoelectric micro-electro-mechanical systems (piezo-MEMS) devices. In this work, we successfully sputter-deposited highly (100) oriented BiFeO thick films (∼1 μm) on Si at 350 °C through the use of a conductive perovskite buffer layer of LaNiO. Formation of bulk and interfacial defects is suppressed by the combination of a low deposition temperature and an oxygen-rich processing atmosphere, resulting in chemically stoichiometric BiFeO films. These films displayed a high (∼60 μC·cm), a low ε (∼200), and a small dielectric loss (<0.02), as well as large coercive and self-bias voltages in their as-grown and aged states. Together with a large transverse piezoelectric coefficient ( ∼ -2.8 C·m), excellent electromechanical performances with outstanding fatigue and aging resistances are demonstrated in patterned BiFeO-Si cantilever devices. These integration-friendly BiFeO films are ideal replacements of PZT films in piezo-MEMS applications.
作为一种原型单相多铁性材料，BiFeO₃展现出优异的电学、磁学和磁电性能，在许多现代技术应用中颇具吸引力。其一个被忽视的优点是源于其大的剩余极化（）和低介电常数（ε）的高压电性能。此外，其高居里温度和大矫顽场确保了在器件应用中的良好稳定性。然而，为了实现接近本征的性能，通常采用高温处理来制备高结晶度（外延或高度取向）的BiFeO₃薄膜。高温过程中挥发性BiO的损失导致缺陷增殖，以及它与CMOS - Si技术的不兼容性阻碍了基于BiFeO₃薄膜的压电微机电系统（piezo - MEMS）器件的发展。在这项工作中，我们通过使用LaNiO₃的导电钙钛矿缓冲层，在350℃下成功地在Si上溅射沉积了高度（100）取向的BiFeO₃厚膜（约1μm）。低沉积温度和富氧处理气氛的结合抑制了体缺陷和界面缺陷的形成，从而得到化学计量比的BiFeO₃薄膜。这些薄膜表现出高的（约60μC·cm⁻²）、低的ε（约200）和小的介电损耗（<0.02），以及在生长态和老化态下的大矫顽电压和自偏置电压。连同大的横向压电系数（约 - 2.8 C·m⁻²），在图案化的BiFeO₃ - Si悬臂器件中展示了具有出色疲劳和老化抗性的优异机电性能。这些易于集成的BiFeO₃薄膜是piezo - MEMS应用中PZT薄膜的理想替代品。
