Ultralong Single-Crystal α-Bi₄Br₄ Nanobelts with a High Current-Carrying Capacity by Mechanical Exfoliation

Abstract

Mechanical exfoliation is of great potential in the preparation of two-dimensional (2D) materials such as graphene and transition metal dichalcogenides, offering new opportunities for exploring extraordinary electronic, optic, optoelectronic, and spintronic properties of low-dimensional materials. However, the extension of the exfoliation method from 2D van der Waals materials to one-dimensional (1D) materials has rarely been reported. Here, we show that the 1D α-Bi 4 Br 4 nanobelts can be prepared by direct exfoliation of single crystals, as characterized by optical microscopy, scanning electron microscopy, atomic force microscopy, transmission electron microscopy, and Raman spectroscopy. Electrical transportation measurements indicate that the nanobelts maintain the intrinsic semiconducting properties of the bulk. Remarkably, the nanobelts can bear a very high current density up to 10 6 Acm −2 at room temperature, much higher than that of most semiconducting nanowires reported so far and comparable with that of Cu or Ag. This behavior is attributed to their 1D topological edge states. Our work demonstrates that mechanical exfoliation is an effective way to prepare high-quality α-Bi 4 Br 4 nanobelts for the investigation of fundamental topological physics and the development of high-performance electronic devices.

Low‐Frequency Current Fluctuations in Quasi‐1D (TaSe4)2I Weyl Semimetal Nanoribbons

“…[9,11] Previous studies reported that in some topological semimetals, the resistivity can decrease with the decreasing cross-sectional area of the conductors. [27][28][29]70] In our present study, the resistivity values that we obtained for nanoribbons of different sizes were not sufficient to claim the specific trend with the cross-section area within the standard error of the measurements. It was recently reported that annealing, i.e., due to heating or passing current, can improve the current conduction in thinner films of topological semimetals.…”

“…It is not possible to state at this point if the low level of noise in (TaSe 4 ) 2 I nanoribbons is due to the current fluctuation suppression in the topologically protected conductive channels of the Weyl semimetal. [68][69][70] The latter would require a dedicated theoretical study allowing to connect the electron scattering and capture rates with the fluctuations in the number of electrons and their mobility. The experimental data reported in this study indicate an unexpectedly low noise level and motivate future studies.…”

Low-dimensional van der Waals materials for linear-polarization-sensitive photodetection: materials, polarizing strategies and applications

“…Of note, the particular 1D atomic bonding makes 1D vdWMs prone to exist in the form of nanowires [97], nanotubes [101], nanoribbons [115], nanofibrous [116], nanobelts [117], and other ganging morphologies, which is adverse to the construction of device array. Compared to 1D vdWMs, the large-scale preparation of 2D vdWMs is much simpler, laying a solid foundation for the on-chip integration of corresponding functional devices.…”

“…In this consideration, the polarization-dependent photosensitivity of photodetectors built of novel low-symmetry vdWMs (e.g. MoI 3 [79], Nb 2 Se 9 [287], α-Bi 4 Br 4 [117], Ta 2 Ni 3 Se 8 [288], GePdS 3 [58], CrSbSe 3 [289], BiSeI [290], Ta 2 Se 3 [291], AsSbO 3 [292], AsSbS 3 [293]…”