Figure 1: Circular photo-galvanic effect in lead sulfide nanosheet devices.
From: Towards colloidal spintronics through Rashba spin-orbit interaction in lead sulphide nanosheets
(a) Schematic image of the experimental setup. The semiconductor channel (PbS nanosheet, shown in grey) experiences an electric field and asymmetric interfaces (vacuum and SiO2, shown in blue) and is illuminated with circularly polarized light. (b) Breaking the inversion symmetry in a PbS crystal. The symmetry is reduced from Oh point group (for the bulk crystal) to C4v (2D crystal with external asymmetries). The blue and violet spheres represent lead and sulfur atoms respectively. The arrow shows the asymmetry in the crystal, including the gate electric field and the asymmetric interfaces. (c) Photocurrent at zero bias as a function of the quarter-wave plate angle (with a small non-zero incidence illumination angle). Fitting the results shows the existence of a non-zero CPGE current, suggested to originate from Rashba SOC in PbS nanosheets (LPGE: linear photo-galvanic effect). The arrows show the quarter-wave plate angles, in which the light is circularly or linearly polarized.
