The conductivity of Bi(111) investigated with nanoscale four point probes

Abstract

The room temperature conductance of Bi͑111͒ was measured using microscopic four point probes with a contact spacing down to 500 nm. The conductance is remarkably similar to that of the bulk, indicating that surface scattering is not a major mechanism for restricting the mobility at this length scale. Also, the high density of electronic surface states on Bi͑111͒ does not appear to have a major influence on the measured conductance. The lower limit for the resistivity due to electronic surface states is found to be around 5 ⍀. With such a value for the surface resistivity, surface conduction should not be a significant factor to inhibit the observation of the predicted semiconductor to semimetal transition for thin films of Bi.

Detecting the local transport properties and the dimensionality of transport of epitaxial graphene by a multi-point probe approach

“…Then, instead of plotting the measured resistance as a function of contact spacing, we apply a geometric transformation, that allows us to plot a graph between the "corrected resistance" R 0 ¼ v 2D R and the "corrected spacing" s 0 ¼ s ef f =v 2D , quantities with units of ohms and metres, respectively. 19,23 As in the case of a variable spacing, R 0 is independent of s 0 for 2D transport and inversely proportional to s 0 for 3D transport. The most significant assumption made in this treatment is that the surface and bulk can be treated as parallel resistors.…”

“…21,22 This is not an option for a monolithic probe with a fixed contact spacing but we have recently shown that a multi-point probe can be used to emulate a variable contact spacing by choosing different combinations of contacts as current sources and voltage reference. 19 Actual resistance measurements are made by ramping the current through the sample while measuring the voltage drop, leading to an I/V curve that gives the resistance via a linear fit. The I/V curves are routinely taken with the current ramped in both directions because this permits the easy identification of capacitance-induced artefacts.…”

“…This may not be surprising for graphene on SiC, but it is in drastic contrast to a study of Bi(111), a semimetal surface with metallic surface states, 27 for which only the three dimensional bulk transport has been detectable. 19 For many interesting materials, such as the topological insulators, 28 there will be a competition between bulk and surface transport and the approach presented here should be able to single out the surface contribution.…”

One-dimensional spin texture of Bi(441): Quantum spin Hall properties without a topological insulator

“…Although the surface properties of Bi (441) show much promise for spintronics, there is a sufficient contribution of unpolarised bulk states to dominate the transport [36]. In order to utilise the surface spin-transport properties in a real device, it would be necessary to reduce the contribution from the bulk.…”

Few‐layer Bismuthene: Sonochemical Exfoliation, Nonlinear Optics and Applications for Ultrafast Photonics with Enhanced Stability

“…[8,9] If the thickness of bismuthene becomes thinner than the Fermi wavelength, there could be a transition from semimetal to semiconductor because of the quantum confinement effect. [10][11][12][13][14] In 1991, surface superconductivity studies of bismuth by Weitzel and Micklitz [15] provided experimental evidence of a size dependence of the superconducting transition temperature. Sunglae Cho et al observed a significant enhancement of magnetoresistance in bismuth thin films by molecular beam epitaxial [16] based on the high hole and electron motilities.…”