Jain Achint, Szabó Áron, Parzefall Markus, Bonvin Eric, Taniguchi Takashi, Watanabe Kenji, Bharadwaj Palash, Luisier Mathieu, Novotny Lukas
Photonics Laboratory , ETH Zürich , 8093 Zürich , Switzerland.
Integrated Systems Laboratory , ETH Zürich , 8092 Zürich , Switzerland.
Nano Lett. 2019 Oct 9;19(10):6914-6923. doi: 10.1021/acs.nanolett.9b02166. Epub 2019 Sep 23.
Integration of electrical contacts into van der Waals (vdW) heterostructures is critical for realizing electronic and optoelectronic functionalities. However, to date no scalable methodology for gaining electrical access to buried monolayer two-dimensional (2D) semiconductors exists. Here we report viable edge contact formation to hexagonal boron nitride (hBN) encapsulated monolayer MoS. By combining reactive ion etching, in situ Ar sputtering and annealing, we achieve a relatively low edge contact resistance, high mobility (up to ∼30 cm V s) and high on-current density (>50 μA/μm at = 3V), comparable to top contacts. Furthermore, the atomically smooth hBN environment also preserves the intrinsic MoS channel quality during fabrication, leading to a steep subthreshold swing of 116 mV/dec with a negligible hysteresis. Hence, edge contacts are highly promising for large-scale practical implementation of encapsulated heterostructure devices, especially those involving air sensitive materials, and can be arbitrarily narrow, which opens the door to further shrinkage of 2D device footprint.
将电接触集成到范德华(vdW)异质结构中对于实现电子和光电子功能至关重要。然而,迄今为止,还不存在用于获得对埋入式单层二维(2D)半导体进行电接触的可扩展方法。在此,我们报告了一种对六方氮化硼(hBN)封装的单层MoS实现可行边缘接触形成的方法。通过结合反应离子刻蚀、原位氩溅射和退火,我们实现了相对较低的边缘接触电阻、高迁移率(高达约30 cm² V⁻¹ s⁻¹)和高导通电流密度(在V = 3V时>50 μA/μm),与顶部接触相当。此外,原子级光滑的hBN环境在制造过程中也保留了本征MoS沟道质量,导致亚阈值摆幅陡峭,为116 mV/dec,滞后可忽略不计。因此,边缘接触对于封装异质结构器件的大规模实际应用极具前景,尤其是那些涉及对空气敏感材料的器件,并且可以任意变窄,这为进一步缩小二维器件尺寸开辟了道路。