Non-equilibrium Green’s function approach for simulation asymmetric source-drain silicene-based photodetectors

Abstract

Photodetectors based on Armchair-Silicene-Nanoribbons (ASiNR) with asymmetric source (Ir-doped silicene) and drain (Cu-, Ag-, or Au-doped silicene) contacts have been simulated employing tight-binding approximation coupling to Non-Equilibrium Green’s Function (NEGF) approach. Monochromatic 1 kW cm−2 illumination in the range of 0.1–10 eV has been used for the simulation of the photocurrent, photoresponsivity, quantum efficiency, and detectivity. It is shown that the highest peak in the photocurrent spectrum occurs at the 273 nm incident wavelength for all devices, and the Ir-Cu device has presented enhanced photodetector characteristics than Ir-Ag and Ir-Au devices. It is also found that only transitions between two subbands with identical indexes are allowed. Moreover, the first peak in the photocurrent spectrum is related to the main band gap of ASiNR. Additionally, the simulated dark and total currents versus source-drain voltage reveal that photocurrent caused a negative shift in the total current proportional to incident light intensity.