Highly responsive photoconductance in a Sb2SeTe2 topological insulator nanosheet at room temperature

A photocurrent was applied to a Sb 2 SeTe 2 topological insulator nanosheet at a wavelength of 325 nm, and it exhibited extremely high performance such that the responsivity and photoconductive gain are 354 A W −1 and 1531, respectively, at a bias of 0.1 V. This photoresponse is orders of magnitude higher than most reported values for topological insulators and two-dimensional transitional metal dichalcogenides. The photoresponse is linear with the applied voltage. Responsivity and gain under vacuum are higher than that in air by a factor of 2.5. This finding suggests that the Sb 2 SeTe 2 topological insulator nanosheet has great potential for ultraviolet optoelectronic device applications. SEM picture of the Sb 2 SeTe 2 nanosheet. The top-right figure shows the linear current-voltage curve indicating the ohmic contact between the Pt electrodes and Sb 2 SeTe 2 nanosheet.