摘要
二维材料因其原子级的厚度而展现出优异的电学、光学、磁学和热学性质,在电子、光电和能源等领域具有广阔的应用前景.随着传统硅基器件逼近物理极限,摩尔定律的延续面临着巨大挑战,二维材料被寄望于超越硅基材料以实现新一代电子器件的构建.可控制备大尺寸单晶二维薄膜是实现其高性能和大规模应用的关键.过去十几年来,研究人员在二维单晶的材料生长方面付出了大量努力,典型的二维导体石墨烯、半导体过渡金属硫族化合物和绝缘体六方氮化硼的生长尺寸已经由微米级扩展到晶圆级.然而,二维材料薄膜通常需要覆盖在绝缘衬底上才能充分发挥性能,因此在绝缘衬底直接生长二维单晶材料是实现高性能电子和光电子器件的终极目标.本文从绝缘衬底上不同种类二维单晶材料的生长行为展开探讨,回顾了近十年来过渡金属硫族化合物、石墨烯和氮化硼在绝缘衬底上的生长策略以及机理,对绝缘衬底上制备高质量二维单晶材料面临的挑战和未来发展进行了总结和展望.
Abstract
Two-dimensional(2D)materials,characterized by their atomic thickness and exceptional electrical,optical,magnetic,and thermal properties,hold great promise for applications in electronics,optoelectronics,and energy.As silicon-based transistors approach their theoretical physical limits,the continuation of Moore's law faces significant challenges.It is expected that 2D materials will surpass silicon-based materials to enable the development of a new generation of electronic devices.The key to achieving their high performance and large-scale applications lies in the controllable preparation of large-sized single-crystal 2D films.Over the past decade,substantial progress has been made in growing single crystal 2D materials such as graphene(a typical 2D conductor),semiconductor transition metal chalcogenides(TMD),and insulators like hexagonal boron nitride(hBN).These materials have expanded from micron-level sizes to wafer scales.However,for optimal performance,it is generally necessary to layer 2D material films on insulating substrates.Therefore,the ultimate goal is direct growth of single-crystal 2D materials on insulating substrates.Due to the inherent properties of insulating substrates,such as their catalytic inertness towards precursor decomposition and the high energy barrier for reactive substances like carbon and boron nitride,growing 2D materials,especially graphene and hBN,on insulating substrates presents unique challenges.In contrast to metal substrates,the coupling interaction between 2D materials and insulating substrates is notably weak.As a result,obtained graphene and hBN films often exhibit significant defects and limited crystal quality,which negatively impact the physical integrity and electrical performance of devices based on these 2D materials.Consequently,achieving orientation control of 2D domains on insulating substrates proves exceptionally challenging.In this review,we first discussed the growth behavior of 2D materials on different substrates,including both catalytic and non-catalytic substrates.Subsequently,we reviewed the progress on the direct growth of 2D materials on insulating substrates,and we focused on the advancements made in producing representative 2D single crystals,including TMD,graphene and hBN.In detail,we reviewed the progress in the preparation of TMD single crystals on insulating substrates,including the synthesis discussion of atomic step control and seed crystal-assisted growth.We also discussed the advancements in the preparation of graphene single crystals on insulating substrates,such as the high-temperature growth of graphene using electromagnetic induction heating and the growth of graphene through multi-cycle plasma etching-assisted-chemical vapor deposition.Besides,we primarily discussed the scalability of atomic stamping techniques in the preparation of large-area hBN single crystals.These techniques have proven to be effective in producing high-quality 2D single crystals on specific insulating substrates.Finally,we discussed existing challenges and future perspectives regarding the direct growth of high-quality 2D materials on insulating substrates and looked forward to future research on the direct growth on semiconductor devices at low-temperatures,the growth of layer-,stacking-,and twist-controlled 2D single crystals and their heterostructures.In conclusion,the direct growth of 2D single crystals on insulating substrates is a rapidly evolving field with significant potential for future technological advancements.We hope this review can propel in-depth comprehension of the direct growth of 2D single crystals on insulators.
维普
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