SURFACE AND INTERFACE ENGINEERING FOR TWO-DIMENSIONAL MATERIALS TOWARDS FUNCTIONAL DEVICES

Abstract

The performance of 2D materials-based functional devices is largely determined by the properties of their surface/interface. In this thesis, two kinds of surface/interface engineering methods are used to optimize the performance of 2D devices. Firstly, through MoO3 surface modification, a high-performance in-plane SnS2 phototransistor is demonstrated. The improved photodetection performance is attributed to the formation of an out-of-plane built-in electric field because of the p-type doping effect of MoO3 on the SnS2 channel. Then, the performance of a hybrid system combining 2D MoTe2 and Hf0.5Zr0.5O2 ferroelectric thin film is studied. By leveraging the synergetic effect of ferroelectric polarization and charge trapping behavior at the interface, the device can work as a reliable memory device, a tunable artificial synapse, and a reconfigurable photodetector. To further meet the scaling requirement for denser integration on the chip, α-In2Se3, a 2D layered semiconductor with intrinsic ferroelectricity is employed directly to fabricate artificial synapse.