Fig. 1: Crystal structure and photocurrent response of Ag₂Te.

a, b Unit cell of Ag₂Te in three-dimensional perspective (a) and the projection of \((100)\) plane (b). The inky blue axis, the orange-pink plane, and the black dot indicate the screw rotation axis \({C}_{2b}\), the glide mirror plane \(\widetilde{{M}_{b}}\) and the center of inversion symmetry, respectively. The colorized axes show the unit cell vectors. The dashed black axes in a show the laboratory coordinates, where the nanoplate surface (\(\bar{1}01\)) is parallel to the x-y plane. b Schematic of the microscopic symmetry operations. The blue-outlined polyhedron transforms to the dotted blue one after the operation of a pure rotation and then coincides with the yellow one after a glide of 1/2b along the b-axis. The red-outlined polyhedron transforms to the dotted red one after the operation of a pure mirror and then coincides with the yellow one after a glide of 1/2c along the c-axis. c Main: power dependence of the photocurrent response in Ag₂Te. The red points are the measured data and the black solid line is the fitting curve of I ∝ P^1.1, respectively. Inset: false-color optical image of the device with the scheme of the short-circuit photocurrent measurement. d Mapping of the photocurrent response of the device. The laser wavelength in c, d is 690 nm and the power in d is ~70 μW. The scale bars are all 5 μm.