Temperature-Dependent Phase Transition in WS₂ for Reinforcing Band-to-Band Tunneling and Photoreactive Random Access Memory Application

In the era of big data, negative differential resistance (NDR) devices have attracted significant attention as a means of handling massive amounts of information. While 2D materials have been used to achieve NDR behavior, their intrinsic material characteristics have produced limited performance improvements. In this article, a facile phase modification method is presented via a plasma-assisted sulfidation process to synthesize multiphased WS₂ thin films, including distorted 1 T (D-1 T) phase and 2 H phases for photoreactive NDR devices with p-Si. The D-1 T phase offers a feasible route to achieve high-performance NDR devices with excellent stability and semimetallic properties. A comprehensive investigation of experimental and computational analyses elucidates the phase transition mechanism with various temperatures and electrical properties of D-1 T WS₂. In addition, optimizing electron tunneling in the multiple-phased tungsten disulfide (MP-WS₂)/p-Si heterojunction at MP-WS₂ with 77.4% D-1 T phase results in superior NDR performance with a peak-to-valley current ratio of 13.8 and reliable photoreactive random-access memory. This unique phase engineering process via plasma-assisted sulfidation provides a pioneering perspective in functionalization and reliability for next-generation nanoelectronics.