AVS 61st International Symposium & Exhibition
    2D Materials Focus Topic Monday Sessions
       Session 2D+AS+EM+NS+SS-MoA

Invited Paper 2D+AS+EM+NS+SS-MoA1
Cutting and Assembling 2 Nanometer Voids in Single Layer Hexagonal Boron Nitride

Monday, November 10, 2014, 2:00 pm, Room 310

Session: Dopants, Defects, and Interfaces in 2D Materials 
Presenter: Thomas Greber, University of Zurich, Switzerland
Authors: T. Greber, University of Zurich, Switzerland
H.Y. Cun, University of Zurich, Switzerland
M. Iannuzzi, University of Zurich, Switzerland
A. Hemmi, University of Zurich, Switzerland
J. Osterwalder, University of Zurich, Switzerland
Correspondent: Click to Email
Argon implantation beneath hexagonal boron nitride nanomesh on Rh(111) [1] leads to the formation of vacancy and interstitial defects [2]. The nanomesh is a single layer of hexagonal boron nitride on Rh(111), where 13x13 h-BN units accommodate on 12x12 Rh unit cells. The resulting super-honeycomb has a lattice constant of 3.2 nm and consists in regions where the h-BN “wets” the Rh substrate (pores), and regions where h-BN is quasi freestanding (wires) [3].

The interstitial defects are called “nanotents”, where atoms are trapped beneath the ultimately thin “rainfly” made of a single layer of h-BN [2,4]. They are stable at room temperature and survive exposure to air.

The vacancy defects are sites where a boron or a nitrogen atom was kicked out by the Ar ion impact. If the implanted structures are annealed to 900 K the can-opener effect occurs: 2 nm h-BN-flakes or “lids” are cut out of the h-BN nanomesh and 2 nm voids form [2]. At higher temperatures the resulting voids may diffuse and assemble, due to their repulsive interaction, in a super-superstructure with some order, i.e., a nearest neighbor distance of about 15 nm. Near the disintegration temperature of the h-BN nanomesh we finally observe self-healing of the voids in the nanomesh, which we assign to their annihilation in larger holes in the structure.

The report bases on scanning tunneling microscopy, x-ray photoelectron spectroscopy, molecular dynamics and density functional theory calculations.

Financial support by the Swiss National Science Foundation and support by the EC under the Graphene Flagship (contract no. CNECT-ICT-604391) is gratefully acknowledged. We thank the Swiss National Supercomputer Centre (CSCS) for allocation of computer time.

[1] M. Corso et al. Science, 303 (2004) 217.

[2] H. Y. Cun et al. Nano Letters 13 (2013) 2098.

[3] S. Berner et al. Angew. Chem. Int. Ed. 46 (2007) 5115.

[4] H.Y. Cun et al. ACS Nano 8 (2014) 1014.