Enhanced Electrical Polarization in van der Waals α‐In2Se3 Ferroelectric Semiconductor Field‐Effect Transistors by Eliminating Surface Screening Charge

Abstract A van der Waals (vdW) α‐In 2 Se 3 ferroelectric semiconductor channel–based field‐effect transistor (FeS‐FET) has emerged as a next‐generation electronic device owing to its versatility in various fields, including neuromorphic computing, nonvolatile memory, and optoelectronics. However, screening charges cause by the imperfect surface morphology of vdW α‐In 2 Se 3 inhibiting electrical polarization remain an unresolved issue. In this study, for the first time, a method is elucidated to recover the inherent electric polarization in both in‐ and out‐of‐plane directions of the α‐In 2 Se 3 channel based on post‐exfoliation annealing (PEA) and improve the electrical performance of vdW FeS‐FETs. Following PEA, an ultra‐thin In 2 Se 3−3x O 3x layer formed on the top surface of the α‐In 2 Se 3 channel is demonstrated to passivate surface defects and enhance the electrical performance of FeS‐FETs. The on/off current ratio of the α‐In 2 Se 3 FeS‐FET has increased from 5.99 to 1.84 × 10 6 , and the magnitude of ferroelectric resistance switching has increased from 1.20 to 26.01. Moreover, the gate‐modulated artificial synaptic operation of the α‐In 2 Se 3 FeS‐FET is demonstrated and illustrate the significance of the engineered interface in the vdW FeS‐FET for its application to multifunctional devices. The proposed α‐In 2 Se 3 FeS‐FET is expected to provide a significant breakthrough for advanced memory devices and neuromorphic computing.