二维原子晶体半导体转移技术研究进展

Recent progress on transfer techniques of two-dimensional atomically thin semiconductor

实现不同基底间高效率、高质量的二维原子晶体转移(即转移技术),是开展二维晶体异质结及柔性器件研究与应用的关键.近年以二硫化钼为代表的过渡金属硫化物(transition metal dichalcogenides,TMDs)二维半导体已成为继石墨烯之后的二维材料研究热点.目前,TMDs常用转移技术主要包括湿法转移、干法转移、热释放胶带辅助、表面能辅助、鼓泡转移以及真空热压法等.这些方法各有利弊:湿法转移成本低、步骤简洁,但依赖聚合物支撑,容易对TMDs造成污染;干法转移借助精密位移技术可实现精准控制,特别适用微晶定位转移,但转移成功率有待提升;热释放胶带巧妙利用金属膜与TMDs二维材料间较强的吸附力,能够在不转移的情况下,直接在原始基底上构造阵列结构,但步骤相对复杂;表面能辅助法利用水在不同界面表面能差异,可实现快速自动剥离,但易引入褶皱;鼓泡转移则是通过电化学或超声方式产生的气泡崩塌使二维材料与基底界面分离,同样材料表面容易产生褶皱和破裂等缺陷;真空热压法在组装高质量、大面积多层异质结方面独具优势.该述评可为恰当选择转移方法提供指引.

High efficiency and high quality transfer techniques of two-dimensional（2D） materials between different substrates are vital for fabrication of 2D heterojunctions and their flexible devices. Triggered by graphene,2D transition metal dichalcogenides（TMDs） are becoming a hot topic in 2D material research community. In the past few years,various transfer techniques mainly including wet transfer,dry transfer,thermal release tape assisted,surface energy assisted transfer,bubble transfer,and programmed vacuum stack transfer have been demonstrated.Their comparisons show that the wet transfer is the most popular one,but it relies on the polymer support and is prone to contamination of 2D materials. The dry transfer is carried out under the precise position control by a three-dimensional micromanipulator, therefore, it is suitable for building heterojunctions based on mechanical exfoliated microflake crystals. However,the efficiency is still relatively low. The thermal release tape assisted technique utilizing the strong adhesion force between the metal film and the TMDs can construct arrays directly on original substrate without transfer,however the steps are relatively complex.The surface energy assisted transfer can realize fast and automatically peel off the TMDs from the substrates according to the difference of surface energies,but it is easy to introduce folds.The bubble transfer is carried out by the bubble collapse caused by ultrasonic or electrochemical reaction,then separates the 2D material from the substrate,but the surface of the TMDs is prone to wrinkle and fracture.Recently,programmed vacuum stack shows unique advantages in assembling multi-layer heterojunction with large-scale and high-quality.This review not only provides a scientific reference for on-demand transfer method selection,but also sheds light on the development of new transfer technologies.