Figure 2: Results of the STP measurement.
From: Nanoscale electron transport at the surface of a topological insulator
(Vmod =20 mVpp at 2.1 kHz, It = 12 pA, Vtrans=−1.3 V, Itrans=−1.9 mA, 315 × 315 nm2). White scale bar, 75 nm. (a) Topography of the Bi2Se3 film. (b) The image of the potential for the corresponding surface area as in a mainly exhibits a constant gradient corresponding to the electric field induced by the contacting tips. (c) Corresponding ‘fine structure’ of the potential (gradient subtracted). The colour coding helps to identify rather sharp drops of the potential at surface step edges. (d) Averaged line profiles (about 7 scan lines) across a Bi2Se3 island for the same position as marked in a,b and c. The plot of the fine structure includes the profile for the backward scan direction (light grey). The scan direction is indicated by arrows.
