Abstract
The confinement effect of intercalated atoms in van der Waals heterostructures can lead to interesting interactions between the confined atoms or molecules and the overlaying two-dimensional (2D) materials. Here we report the formation of ordered Cu(100) p(2×2) oxygen superstructures by oxygen intercalation under the monolayer hexagonal boron nitride (h-BN) on Cu after annealing. By using scanning tunneling microscopy and x-ray photoelectron spectroscopy, we identify the superstructure and reveal its roles in passivating the exposed Cu surfaces, decoupling h-BN and Cu, and disintegrating h-BN monolayers. The oxygen superstructure appears as a 2D pattern on the exposed Cu surface or quasi-1D stripes of paired oxygen intercalated in the interface of h-BN and Cu predominantly oriented along the moiré modulations. The oxygen superstructure is shown to etch the overlaying h-BN monolayer in a thermal annealing process. After extended annealing, the h-BN monolayer disintegrates into nanoislands with zigzag edges. We discuss the implications of these findings on the stability and oxidation resistance of h-BN and relate them to challenges in process integration and 2D heterostructures.
Original language | English |
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Article number | 064106 |
Journal | Physical Review B |
Volume | 94 |
Issue number | 6 |
DOIs | |
State | Published - Aug 18 2016 |
Funding
This research was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility. STM measurements by C.M. were supported by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U. S. DOE. The work at UTK was supported by NSF (Grant No. ECCS-1231808) and DARPA (Grant No. HR0011-13-2-0016). Computational research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility under Contract No. DE-AC02-05CH11231.