High-Detectivity and Broadband MoS2 Phototransistor Array by Coupling Negative Capacitance and Local Surface Plasmon Resonance Effects

This work introduces a groundbreaking MoS2 phototransistor with exceptional detectivity and broad-spectrum response, achieved through the synergy of an HZO ferroelectric film and in situ-prepared Au nanoparticles (AuNPs). In situ prepared AuNPs enhance the ferroelectricity of the HZO film. The innovative approach involves inserting an Al2O3 layer between AuNPs/MoS2. The Al2O3 layer reduces the off-state current, preserving the local surface plasmon resonance (LSPR) effect of AuNPs. The tensile strain induced by AuNPs in MoS2 narrows its bandgap for broadband photodetection. Also, Al2O3 acts as a capacitance-matching layer, reducing subthreshold swing and enhancing detectivity through the negative capacitance (NC) effect of the ferroelectric HZO film. The NC-LSPR-coupled phototransistor demonstrates outstanding responsivity and detectivity at 528 nm (122.5 A/W, 3.23 × 1014 Jones) and 740 nm (28.3 A/W, 9.14 × 1013 Jones). This pioneering integration of NC and LSPR effects in 2D photodetectors paves the way for large-area phototransistor arrays with superior detection and broadband detection capabilities.