Extended Data Fig. 4: Band structure measurement of BP-Bi near the Fermi surface.
From: Two-dimensional ferroelectricity in a single-element bismuth monolayer
a, A typical dI/dV spectrum acquired on the BP-Bi shows a band gap above the Fermi surface (initial setpoint: V = 500 mV, I = 1.0 nA). b, STM image (V = −70 mV, I = 150 pA) of a single domain area. c,d, dI/dV maps (left panel) and Fourier-transformed dI/dV maps (right panel) of conduction band (c) and valence band (d) are measured at the area in (b). The atomic Bragg peaks are highlighted by the red dashed circles. e,f, dI/dV line maps (left panel) and corresponding energy-resolved Fourier transformation (right panel) for the conduction band (e) and valence band (f) along the armchair direction (initial setpoint: V = 500 mV, I = 1.3 nA (e); V = −350 mV, I = 1.0 nA (f)). The parabolic fittings and trajectories (red dashed lines) for the dI/dV measurements at VBM and CBM are shown in corresponding insets (V = 400 mV, I = 15 pA (e); V = 450 mV, I = 15 pA (f)).
