Electron radiation damage mechanisms in 2D MoSe2

Abstract

The contributions of different damage mechanisms in single-layer MoSe 2 were studied by investigating different MoSe 2 /graphene heterostructures by aberration-corrected high-resolution transmission electron microscopy (AC-HRTEM) at 80 keV. The damage cross-sections were determined by direct counting of atoms in the AC-HRTEM images. The contributions of damage mechanisms such as knock-on damage or ionization effects were estimated by comparing the damage rates in different heterostructure configurations, similarly to what has been earlier done with MoS 2 . The behaviour of MoSe 2 was found to be nearly identical to that of MoS 2 , which is an unexpected result, as the knock-on mechanism should be suppressed in MoSe 2 due to the high mass of Se as compared to S.

Structural characterization of SnS crystals formed by chemical vapour deposition

“…Contrary to most metaldichalcogenides studied in the literature (Zan et al, 2013;Garcia et al, 2014;Lehnert et al, 2017) the SnS structure is quite stable during electron beam irradiation in the TEM even at 300 kV. This is to a large extent due to the larger thickness of the cross-sectional TEM specimens of the investigated flakes/crystallites compared to monolayers of metaldichalcogenides studied in-plane view TEM specimens.…”

High optical quality of MoS 2 monolayers grown by chemical vapor deposition

“…1d shows an enlarged image of the area marked with a red square in Fig. 1b, where some double sulfur vacancies typically present in the ML MoS 2 samples [29,[45][46][47], can be recognized.…”

Observation of charge density waves in free-standing 1T-TaSe2 monolayers by transmission electron microscopy

“…25 single-layer TMDs have shown that electron beam-induced damage can lead to rapid generation of structural defects through other mechanisms, which include electronic excitations, especially for insulating materials, and beam-induced chemical etching. 26,27 The effects of electron beam-induced damage can be reduced by protecting the single-layer TMD with one graphene layer or sandwiching it between two graphene layers. [27][28][29] Here, we investigate the single-layer 1T-TaSe 2 /graphene heterostructure.…”

“…26,27 The effects of electron beam-induced damage can be reduced by protecting the single-layer TMD with one graphene layer or sandwiching it between two graphene layers. [27][28][29] Here, we investigate the single-layer 1T-TaSe 2 /graphene heterostructure. Furthermore, we assume that heating of a few-layer thick sample by the electron beam at 80 kV can be neglected, as experiments and theory indicate.…”