Enhanced performance of MoS2 phototransistors with ferroelectric HfLaON as gate dielectric through NH3-plasma treatment followed by rapid thermal annealing

Abstract

A novel processing method of NH3-plasma treatment followed by rapid thermal annealing (RTA) is used to prepare HfLaON ferroelectric thin films, and obviously enhanced remanent polarization (Pr) and largely decreased gate leakage are obtained. The relevant HfLaON MoS2 phototransistor exhibits a subthreshold swing of 31 mV/dec and remarkable responsivity/detectivity of 941.37 AW−1/3.326 × 1014 cmHz1/2 W−1 at low operating voltages (gate-source voltage of −0.3 V and drain-source voltage of 0.4 V). Meanwhile, the response time of (NH3 plasma + RTA) phototransistor is significantly reduced to 8–12 ms compared to 33∼31 ms for the RTA phototransistor. Microscopic analyses indicate that the involved mechanisms lie in an effective incorporation of N element into the HfLaON thin film to passivate oxygen vacancies and improve interfacial properties. This work provides an effective way to rectify interface issues and optimize the ferroelectric properties of HfLaON thin films, demonstrating a good application prospects of HfO2-based ferroelectric thin films in 2D material-based photodetection field.