Guberna Elizaveta, Margolin Ilya, Kalika Elizaveta, Zarubin Sergei, Zhuk Maksim, Chouprik Anastasia
Moscow Institute of Physics and Technology, Dolgoprudny 141701, Russia.
ACS Appl Mater Interfaces. 2024 Jan 10;16(1):975-984. doi: 10.1021/acsami.3c11141. Epub 2023 Dec 19.
Since ultrathin ferroelectric HfO films can be conformally grown by atomic layer deposition even on complex three-dimensional structures, new horizons in the development of next-generation piezoelectric devices are opened. However, hafnium oxide has a significant drawback for piezoelectric applications: its piezoelectric coefficients are much smaller than those of classical materials currently used in piezoelectric devices. Therefore, new approaches to the development of high-performance piezoelectric devices based on exploiting the unique properties of HfO are of paramount importance. In this work, a giant electromechanical effect in miniature piezoelectric membrane devices based on a 10 nm-thick ferroelectric HfZrO (HZO) film is experimentally demonstrated. Compared to the pure piezoelectric effect in the HZO film, the gain of the electromechanical response in membrane devices reaches 25 times. Numerical simulations confirm that this effect stems from the asymmetric shape of the membranes and can be further improved by designing the device geometry. Furthermore, according to first-principles calculations, an additional opportunity to improve the piezoelectric coefficient, and hence, the device efficiency is provided by the engineering of the mechanical stress in the HZO film. The proposed approach enables the development of new promising piezoelectric devices including miniature reflectors, nanoactuators, and nanoswitches.
由于超薄铁电HfO薄膜即使在复杂的三维结构上也能通过原子层沉积进行保形生长，这为下一代压电器件的发展开辟了新的前景。然而，氧化铪在压电应用方面有一个显著缺点：其压电系数比目前压电器件中使用的传统材料小得多。因此，基于利用HfO的独特性能来开发高性能压电器件的新方法至关重要。在这项工作中，实验证明了基于10纳米厚铁电HfZrO（HZO）薄膜的微型压电薄膜器件中存在巨大的机电效应。与HZO薄膜中的纯压电效应相比，薄膜器件中机电响应的增益达到了25倍。数值模拟证实，这种效应源于薄膜的不对称形状，并且可以通过设计器件几何结构进一步改善。此外，根据第一性原理计算，通过调控HZO薄膜中的机械应力，还有额外的机会提高压电系数，从而提高器件效率。所提出的方法能够开发包括微型反射器、纳米致动器和纳米开关在内的新型有前景的压电器件。
