Dong Rui, Kuljanishvili Irma
Department of Physics, Saint Louis University, St. Louis, Missouri 63103.
J Vac Sci Technol B Nanotechnol Microelectron. 2017 May;35(3):030803. doi: 10.1116/1.4982736. Epub 2017 May 1.
Transition metal dichalcogenide (TMDC) semiconductors have attracted significant attention because of their rich electronic/photonic properties and importance for fundamental research and novel device applications. These materials provide a unique opportunity to build up high quality and atomically sharp heterostructures because of the nature of weak van der Waals interlayer interactions. The variable electronic properties of TMDCs (e.g., band gap and their alignment) provide a platform for the design of novel electronic and optoelectronic devices. The integration of TMDC heterostructures into the semiconductor industry is presently hindered by limited options in reliable production methods. Many exciting properties and device architectures which have been studied to date are, in large, based on the exfoliation methods of bulk TMDC crystals. These methods are generally more difficult to consider for large scale integration processes, and hence, continued developments of different fabrication strategies are essential for further advancements in this area. In this review, the authors highlight the recent progress in the fabrication of TMDC heterostructures. The authors will review several methods most commonly used to date for controllable heterostructure formation. One of the focuses will be on TMDC heterostructures fabricated by thermal chemical vapor deposition methods which allow for the control over the resulting materials, individual layers and heterostructures. Another focus would be on the techniques for selective growth of TMDCs. The authors will discuss conventional and unconventional fabrication methods and their advantages and drawbacks and will provide some guidance for future improvements. Mask-assisted and mask-free methods will be presented, which include traditional lithographic techniques (photo- or e-beam lithography) and some unconventional methods such as the focus ion beam and the recently developed direct-write patterning approach, which are shown to be promising for the fabrication of quality TMDC heterostructures.
过渡金属二硫属化物（TMDC）半导体因其丰富的电子/光子特性以及在基础研究和新型器件应用中的重要性而备受关注。由于范德华层间相互作用较弱的特性，这些材料为构建高质量且原子级锐利的异质结构提供了独特机遇。TMDCs可变的电子特性（例如，带隙及其排列）为新型电子和光电器件的设计提供了一个平台。目前，TMDC异质结构集成到半导体行业受到可靠生产方法选择有限的阻碍。迄今为止所研究的许多令人兴奋的特性和器件架构，很大程度上基于块状TMDC晶体的剥离方法。这些方法通常更难以用于大规模集成工艺，因此，持续开发不同的制造策略对于该领域的进一步发展至关重要。在本综述中，作者强调了TMDC异质结构制造方面的最新进展。作者将回顾目前最常用的几种可控异质结构形成方法。其中一个重点将是通过热化学气相沉积方法制造的TMDC异质结构，该方法能够控制所得材料、单个层和异质结构。另一个重点将是TMDCs的选择性生长技术。作者将讨论传统和非传统的制造方法及其优缺点，并为未来的改进提供一些指导。将介绍掩膜辅助和无掩膜方法，其中包括传统光刻技术（光或电子束光刻）以及一些非传统方法，如聚焦离子束和最近开发的直写图案化方法，这些方法已被证明在制造高质量TMDC异质结构方面很有前景。
