Figure 1

STM images and differential conductance spectroscopy.

(a) The STM image (150 nm × 150 nm) of (Bi_1−xSb_x)₂Te₃ film with x = 0.45. Scanning conditions: V = −1.72 V, I = 207 pA. The inset shows line profile along the blue line marked AA′ in (a). (b) The atomic-resolution STM image (10 nm × 10 nm) obtained on terrace in (a). Scanning parameter is 0.298 V and 207 pA. The lattice constant is about 0.44 nm. The inset shows the atomic-resolution STM image of the Bi₂Te₃ films (5 nm × 5 nm, −0.3 V, 270 pA). (c) Typical dI/dV curves obtained on (Bi_1−xSb_x)₂Te₃ films with x = 0 (black line), 0.45 (red line), 0.62 (green line) and 0.87 (blue line), respectively. The pink arrows show the approximate positions of Dirac point (E_D). (d) Schematic illustration of band structure and surface state of (Bi_1−xSb_x)₂Te₃ films varied with x value. The pink bar shows the evolution of position of Dirac Point with different x values.