Versatile van der Waals epitaxy-like growth of crystal films using two-dimensional nanosheets as a seed layer: orientation tuning of SrTiO3 films along three important axes on glass substrates
Versatile van der Waals epitaxy-like growth of crystal films using two-dimensional nanosheets as a seed layer: orientation tuning of SrTiO3 films along three important axes on glass substrates
复制标题
DOI：
10.1039/c3tc31787k
复制
发表时间：
2014-01-01
影响因子：
6.4
通讯作者：
Sasaki, Takayoshi
中科院分区：
文献类型：
--
作者：
Shibata, Tatsuo;Takano, Hikaru;Sasaki, Takayoshi
获得良好外延的基本要求之一是衬底与生长中的晶体外延层之间的结构紧密匹配。这一限制性要求对其在电子、磁性或光学器件中广泛应用于各种功能晶体薄膜造成了主要障碍。克服这一问题的一种方法是所谓的范德华外延（VDWE）方法，该方法可以有效地在层状材料的劈裂面上实现各种晶体的外延，而没有悬空键。无方向性共价键的弱原子-底物相互作用在VDWE的初始阶段起着至关重要的作用，它极大地放宽了晶格匹配的限制。然而，该方法需要特殊材料作为衬底，这意味着它的适用性是有限的。在这项研究中，这个概念被扩展到无机纳米片的二维（2D）晶格，无机纳米片是通过层状金属氧化物的人工剥离产生的分子薄的二维晶体。通过一种简单的溶液工艺，纳米片可以整齐地覆盖在玻璃等传统基板的表面。与上述层状材料的劈裂面类似，这种衬底由于其悬垂无键性质，可以促进类vdwe晶体的生长。基于这一原理，我们已经证明了高度纹理化（100）、（110）和（111）SrTiO3薄膜的选择性沉积，这是一种重要的功能晶体原型，在覆盖有单层纳米片的玻璃衬底上，具有合适的二维周期性，作为vdwe类薄膜生长的触发因素。纳米片结构的多样性及其在几乎任何衬底上的易于沉积提供了一个显着的优势，扩大了基于功能晶体薄膜的一系列器件的潜在应用。
One of the basic requirements for attaining a good epitaxy is a close structural matching between a substrate and a growing crystal epilayer. This restrictive requirement causes a major obstacle for its wide application to a range of functional crystal films in electronic, magnetic or optical devices. One approach for overcoming this problem is the so-called van der Waals epitaxy (VDWE) method, which can effectively implement the epitaxy of various crystals on cleaved faces of layered materials having no dangling bonds. The weak adatom-substrate interaction without directional covalent bonding plays a crucial role in the initial stage of VDWE, which drastically relaxes the lattice matching limitation. However, the method requires special materials for use as a substrate, thereby meaning that its applicability is limited. In this study, the concept is extended to the two-dimensional (2D) lattice of inorganic nanosheets, which are molecularly thin 2D crystals produced via artificial exfoliation of layered metal oxides. The nanosheets can neatly cover the surface of conventional substrates such as glass via a facile solution-based process. Similar to the above-mentioned cleaved faces of layered materials, such substrates can promote VDWE-like crystal growth because of their dangling bond-free nature. Based on this principle, we have demonstrated a selective deposition of highly textured (100), (110) and (111) SrTiO3 films, a fundamentally important archetype of functional crystals, on glass substrates covered with single-layer nanosheets with suitable 2D periodicities as a trigger for VDWE-like film growth. The rich varieties of nanosheet structures and their facile deposition onto almost any kinds of substrates provide a significant advantage, expanding potential applications for a range of devices based on functional crystal films.