Abstract
Two-dimensional (2D) transition metal dichalcogenides (TMDCs) are the subject of intense investigation for applications in optics, electronics, catalysis, and energy storage. Their optical and electronic properties can be significantly enhanced when encapsulated in an environment that is free of charge disorder. Because hexagonal boron nitride (h-BN) is atomically thin, highly crystalline, and is a strong insulator, it is one of the most commonly used 2D materials to encapsulate and passivate TMDCs. In this report, we examine how ultrathin h-BN shields an underlying MoS2 TMDC layer from the energetic argon plasmas that are routinely used during semiconductor device fabrication and postprocessing. Aberration-corrected scanning transmission electron microscopy is used to analyze defect formation in both the h-BN and MoS2 layers, and these observations are correlated with Raman and photoluminescence spectroscopy. Our results highlight that h-BN is an effective barrier for short plasma exposures (<30 s) but is ineffective for longer exposures, which result in extensive knock-on damage and amorphization in the underlying MoS2.
| Original language | English |
|---|---|
| Article number | 0322011 |
| Journal | Journal of Vacuum Science and Technology, Part A: Vacuum, Surfaces and Films |
| Volume | 39 |
| Issue number | 3 |
| DOIs | |
| State | Published - May 1 2021 |
| Externally published | Yes |
Funding
This work was carried out in part at the Singh Center for Nanotechnology at the University of Pennsylvania, which is supported by the National Science Foundation (NSF) National Nanotechnology Coordinated Infrastructure Program Grant No. NNCI-1542153. D.J., E.A.S., and P.K. acknowledge primary support for this work from via the NSF DMR Electronic Photonic and Magnetic Materials (EPM) core program (Grant No. DMR-1905853) as well as the University of Pennsylvania Laboratory for Research on the Structure of Matter, a Materials Research Science and Engineering Center (MRSEC) supported by the National Science Foundation (No. DMR-1720530). K.S.F. was supported by the LRSM MRSEC REU and the Penn-UPRH Partnership for Research and Education in Materials (PREM), Program No. NSF-DMR-1523463. N.A. and D.J. acknowledge support from Vagelos Integrated Program for Energy Research at the University of Pennsylvania as well as the Center for Undergraduate Research and Fellowships at Penn. D.J. also acknowledges support for this work by the US Army Research Office under Contract No. W911NF1910109. A.C.F. and E.A.S. would like to acknowledge the Vagelos Institute for Energy Science and Technology at the University of Pennsylvania for a graduate fellowship to A.C.F. The authors thank James Horwath for help/assistance in the STEM image histogram analyses. The authors also thank Douglas Yates and Jamie Ford in the Singh Center for Nanotechnology for help with the TEM/STEM measurements. There are no conflicts of interest to declare.