In the Nanotube Research Center at AIST, we have been developing the top-level facilities of electron microscopy which enables the atomic resolution analysis of low-dimensional materials. Point defects and edge structures of graphene have been intensively studied with atomic precision in the last decade ^[1-4]. Because the studies of atomic defects and boundaries are of general interest in the fundamental researches and becoming more and more crucial for technological applications of any nanoscale materials, the atomic scale studies can be also expanded to the other low-dimensional materials.

      Here I demonstrate some examples for atomic-scale imaging and spectroscopy of various low-dimensional materials with interrupted periodicities. Active 4|8 defects are most recently found to be responsible for plastic deformation of hexagonal boron-nitride (h-BN) layers ^[5]. Vacancies and edges with radical bonds are also successfully assigned in h-BN ^{[6, 7]}.  Doping and boundary behaviors of single-layered dichalcogenides (MX₂) are intensively studied because they indeed govern the phase transition behaviors between 2H and 1T phases ^{[8, 9]}. Possible nano-device assembly made of metallic and semiconducting MoS₂ single layers will be also proposed.

 

[1] A. Hashimoto et al., Nature, 430 (2004) pp.870-873

[2] K. Suenaga et al., Nature Nanotech., 2 (2007) pp.358-360

[3] Z. Liu, K. Suenaga, P. Harris and S. Iijima, Phys. Rev. Lett., 102 (2009) 015501

[4] K. Suenaga and M. Koshino, Nature 468, 1088-1090 (2010).

[5] O. Cretu, YC. Lin and K. Suenaga, Nanolett., 14 (2014) pp.1064-1068

[6] C. Jin et al., Phys. Rev. Lett., 102, 195505 (2009)

[7] K. Suenaga, H. Kobayashi, and M. Koshino, Phys. Rev. Lett., 108 075501 (2012).

[8] YC. Lin et al., Adv. Mater. (in press)

[9] YC. Lin et al., submitted.

[10] The work is partially supported by JST Research Acceleration Programme.