DFT-FDTD modeling of a new broadband mid-infrared IGZO thin-film phototransistor based on black phosphorus capping layer incorporating intermediate metallic film

Abstract

Here we present a new broadband mid-Infrared (mid-IR) InGaZnO (IGZO) thin-film phototransistor (TF PT) based on both Black Phosphorus (BP) capping layer incorporating gold (Au) intermediate ultrathin-film. The electronic and optical properties of bulk BP are carried out using density functional theory (DFT) computations, including Perdew-Burke-Ernzerhof Generalized Gradient Approximation (PBE-GGA) and the screened hybrid (YS-PBE0) functionals with van der Waals correction. It is found that BP exhibits interesting performances for mid-IR optoelectronic applications, at room temperature. To enhance the absorption of the BP material for broadband mid-IR spectrum, a new strategy is proposed by optimizing the sensitive layer using finite-difference time-domain (FDTD) modeling and particle swarm optimization (PSO) approaches. The photoresponse properties of the optimized broadband mid-IR IGZO TF PT with BP/Au/BP capping layer are carefully analyzed. It is found that the proposed device shows high photodetection performances with a high current ratio exceeding 180 dB over a wide voltage window. Besides, it is revealed that the introduced ultrathin Au layer within BP enhances the absorbance capability over the mid-IR spectrum, which significantly improves the performance of the broadband mid-IR sensor. Therefore, the proposed approach based on combining DFT analysis with FDTD simulation supported by PSO optimization opens up a new strategy for the development of high-performance optoelectronic devices.