Kim Yeon Soo, Chung Harry, Kwon Suhyoun, Kim Jihyun, Jo William
New and Renewable Energy Research Center (NREC), Ewha Womans University, Seoul, 03760, Korea.
Department of Physics, Ewha Womans University, Seoul, 03760, Korea.
Nano Converg. 2022 Sep 30;9(1):43. doi: 10.1186/s40580-022-00336-4.
Flexible electronics has attracted considerable attention owing to its enormous potential for practical applications in various fields. However, the massive strain produced during bending degrades the device. Especially at grain boundaries, due to the accumulation of defects, this degradation is exacerbated in flexible electronic devices. The importance of electrically inactivated grain boundaries increases as devices scale down to the nanoscale. Here, we propose an HfO thin film that can be used as an excellent material for flexible electronics with versatile functionality, especially for grain boundary passivation. Various electrical phases of HfO thin films with conducting to insulating behavior, which originates from oxygen deficiency, have been fabricated on flexible substrates. Furthermore, owing to the most stable charge state of oxygen vacancies, oxygen-deficient HfO shows p-type conductivity. Current mapping by conductive atomic force microscopy reveals that current flow is hindered at grain boundaries due to the formation of potential barriers. This phenomenon is also observed in bent flexible thin films on convex and concave molds, leading to tensile and compressive strains, respectively. Although the defect concentration increases because of lattice deformation during bending, more holes are trapped at the grain boundaries, resulting in an increased hole barrier height. We believe that grain boundary passivation through hole barrier modulation during bending would pave the way for advances in hafnia-based nanoscale flexible electronics.
柔性电子学因其在各个领域的实际应用中具有巨大潜力而备受关注。然而，弯曲过程中产生的巨大应变会使器件性能下降。特别是在晶界处，由于缺陷的积累，这种性能下降在柔性电子器件中会加剧。随着器件尺寸缩小到纳米尺度，电钝化晶界的重要性日益增加。在此，我们提出一种HfO薄膜，它可作为具有多功能的柔性电子学的优异材料，特别是用于晶界钝化。在柔性衬底上制备了具有从导电到绝缘行为的各种电相的HfO薄膜，这种行为源于氧缺陷。此外，并由于氧空位的电荷状态最为稳定，缺氧的HfO呈现p型导电性。通过导电原子力显微镜进行的电流映射显示，由于势垒的形成，电流在晶界处受阻。在分别导致拉伸应变和压缩应变的凸模和凹模上的弯曲柔性薄膜中也观察到了这种现象。尽管弯曲过程中的晶格变形会导致缺陷浓度增加，但更多的空穴被困在晶界处，导致空穴势垒高度增加。我们认为，通过弯曲过程中的空穴势垒调制实现晶界钝化将为基于氧化铪的纳米级柔性电子学的发展铺平道路。
