1D materials such as nanowires or nanotubes often provide superior properties to its bulk counterparts which can be well utilized in various nanodevices [1, 2]. During the fabrication process of such nanodevices, electron beam is often very widely used, either for observation or for direct fabrication of the devices, e.g., making electrical contacts by electron lithography. However, it is well known that electron beam can induce both reversible and irreversible changes to the 1D material or to the underlying substrate [3, 4, 5]. Subsequently, device properties are often altered. Considering WS2 nanotubes, this effect is very sparsely reported in the literature. The exception is the effect of high energy electrons in TEM [5,6]. To our knowledge, consequences of electron irradiation with lower energies (1-30 kV) and with doses that are commonly used for sample observation or in lithography processes were not systematically examined yet.

In this contribution, we will show that electron irradiation caused by routine device observation in electron microscope is enough to significantly change the result of electrical analysis of individual WS2 nanotubes contacted on a planar substrate. Using in-situ electrical measurement directly inside electron microscope, we address important aspects regarding the influence of electron irradiation onto electrical properties of WS2 nanotubes. The key questions that we answer are: What is the role of acceleration voltage, beam current and total dose? Is the observed change in nanotube’s properties reversible or permanent? If reversible, then how long does it take to return to original state? What is the role of the substrate? We will discuss the mechanism responsible for the changes. Our data show that, in general, the electron dose should be considered when planning the experimental workflow which includes electron beam exposure.

[1] Zhang Ch. et al., Appl. Phys. Lett. 100, 243101 (2012)

[2] Levi R. et al., Nano Lett. 13, 8, 3736 (2013)

[3] Chong P. F. et al., Proceedings of the 2001 8th International Symposium on the Physical and Failure Analysis of Integrated Circuits. IPFA, pp. 55 (2001)

[4] Neelisetty K. K. et al., Microscopy and Microanalysis, 25, 592 (2019)

[5] Ding K.K et al., Nanotechnology, 23, 415703 (2012)

[6] Grillo A. et al., Small, 16, 2002880 (2020)