Figure 2. Time-averaged photocurrents in Bi₂Se₃.

(a) Photocurrent map of I_photo in colour scale. Dotted lines indicate the position of the striplines. Scale bar, 5 μm. (b) Line scan along the black dashed dotted line in (a) with a positive (rightward triangle) and a negative peak (leftward triangle) close to the striplines. Circle denotes position of zero signal of I_photo. (c) Polarization dependence of I_photo. Positions are denoted in (a,b). The symbol denotes linearly polarized (along the x-axis), circularly right-handed polarized and circularly left-handed polarized photons. The background contributions I_thermo are denoted by dashed lines as described in Methods. Experimental parameters: 75-nm-thin Bi₂Se₃ film, E_photon=1.53 eV, P_laser=20 mW and T_bath=295 K.