Polarizable Nonvolatile Ferroelectric Gating in Monolayer MoS₂ Phototransistors

Abstract

Given the requirements for power and dimension scaling, modulating channel transport properties using high gate bias is unfavorable due to the introduction of severe leakages and large power dissipation. Hence, this work presents an ultrathin phototransistor with chemical-vapor-deposition-grown monolayer MoS 2 as the channel and a 10.2 nm thick Al:HfO 2 ferroelectric film as the dielectric. The proposed device is meticulously modulated utilizing an Al:HfO 2 nanofilm, which passivates traps and suppresses charge Coulomb scattering with Al doping, efficiently improving carrier transport and inhibiting leakage current. Furthermore, a bipolar pulses excitable polarization method is developed to induce a nonvolatile electrostatic field. The MoS 2 channel is fully depleted by the switchable and stable floating gate originating from remanent polarization, leading to a high detectivity of 2.05 × 10 11 Jones per nanometer of gating layer (Jones nm −1 ) and photocurrent on/off ratio >10 4 nm −1 , which are superior to the state-of-the-art phototransistors based on two-dimensional (2D) materials and ferroelectrics. The proposed polarizable nonvolatile ferroelectric gating in a monolayer MoS 2 phototransistor promises a potential route toward ultrasensitive photodetectors with low power consumption that boast of high levels of integration.