Surface structure promoted high-yield growth and magnetotransport properties of Bi2Se3 nanoribbons

Abstract

In the present work, a catalyst-free physical vapour deposition method is used to synthesize high yield of Bi 2 Se 3 nanoribbons. By replacing standard glass or quartz substrates with aluminium covered with ultrathin porous anodized aluminium oxide (AAO), the number of synthesized nanoribbons per unit area can be increased by 20–100 times. The mechanisms of formation and yield of the nanoribbons synthesized on AAO substrates having different arrangement and size of pores are analysed and discussed. It is shown that the yield and average length of the nanoribbons can base tuned by adjustment of the synthesis parameters. Analysis of magnetotransport measurements for the individual Bi 2 Se 3 nanoribbons transferred on a Si/SiO 2 substrate show the presence of three different populations of charge carriers, originating from the Dirac surface states, bulk carriers and carriers from a trivial 2DEG from an accumulation layer at the Bi 2 Se 3 nanoribbon interface with the substrate.

High-Yield Growth and Tunable Morphology of Bi2Se3 Nanoribbons Synthesized on Thermally Dewetted Au

“…A significant part of the nanoribbons was found to be growing from the nanoplates seeds ( Figure 4 a), which is consistent with the growth mechanism observed in the similar two-step catalyst-free synthesis process [ 13 , 29 ] when the width of the nanoribbon is governed by the width of the nanoplate facet it starts from.…”

“…These XRD peaks are the most intensive for the Bi 2 Se 3 nanostructures grown on 3 nm (nanoparticle size ~10 nm) thick Au layer ( Figure 5 b), indicating the highest number of the tilted nanoplates in comparison to the other samples and explaining the highest yield of the Bi 2 Se 3 nanoribbons per area unit ( Figure 3 a), as it was reported previously that the tilted nanoplates promote the nanoribbon growth [ 13 ]. Presumably, the large number of tilted nanoplates originates from their growth initiated by the VLS growth mechanism with prevailing Bi 2 Se 3 nucleation mode on the top surface of the Au nanoparticles due to their small diameters [ 31 , 32 ].…”

“…The XRD spectra of Bi 2 Se 3 nanostructures synthesized on the dewetted layers of Au particles of mean diameters ~10 and ~85 nm, obtained from 3 nm and 13 nm thick Au layers, respectively, with the XRD spectra of Bi 2 Se 3 nanostructures grown on a glass substrate by the catalyst-free method showed a decreased intensity of diffraction peaks corresponding to Bi 2 Se 3 nanostructure growth with the c-axis perpendicular to the substrate surface (peaks at 9.26°, 18.58°, and 27.94° correspond to Bi 2 Se 3 crystallographic planes (003), (006), and (009), all belonging to the (003n) group), accompanied by an increase of intensity for diffraction peaks related to other Bi 2 Se 3 crystallographic planes (104), (015), (1010), and (110) ( Figure 5 ). According to previous reports, the increase of intensity of these XRD peaks has a direct correlation with the number of the Bi 2 Se 3 nanoplates tilted relative to the substrate surface under the angles of 35°, 54°, and >65°, respectively, which was confirmed by the AFM [ 35 ] and SEM [ 13 ] characterization.…”

“…However, the unique properties of Bi 2 Se 3 surface states are challenging to utilize practically, as the bulk carriers overwhelm the surface carriers. Bi 2 Se 3 nanostructures, such as nanoplates, nanowires, and nanoribbons, have emerged as perfect candidates for exploiting properties of the topological surface states due to their high surface-to-volume ratio [ 12 , 13 ]. For example, complete suppression of bulk conduction has been demonstrated in Bi 2 Se 3 nanoribbons thinner than 30 nm [ 13 ].…”

“…Bi 2 Se 3 nanostructures, such as nanoplates, nanowires, and nanoribbons, have emerged as perfect candidates for exploiting properties of the topological surface states due to their high surface-to-volume ratio [ 12 , 13 ]. For example, complete suppression of bulk conduction has been demonstrated in Bi 2 Se 3 nanoribbons thinner than 30 nm [ 13 ]. The surface-to-volume ratio has also been shown to play an important role in tuning thermoelectric properties [ 14 ].…”