Figure 3
From: Atomic and electronic structure of an alloyed topological insulator, Bi1.5Sb0.5Te1.7Se1.3
Conductance spectroscopy and maps.
(a), Topograph of the area where the conductance spectra were taken (50 nm × 50 nm, VB = 0.6 V, I = 0.5 nA). (b), Plot of the average conductance spectrum over 256 × 256 regularly spaced points in (a). (c–i) and (j–p), Conductance maps generated from the spectra and their FTs, respectively (VB = −300, −140, 0, 140, 280, 440 and 600 mV). For the FT maps, the centre corresponds to the Γ point of the surface Brillouin zone; the horizontal line indicates the Γ-M direction. All the FT maps were fully symmetrised according to the symmetry of the lattice and then low-pass filtered to reduce the speckle noise. The modulation voltage and frequency for the lock-in amplifier was VM = 5 mV and fM = 1,317 Hz, respectively.
