First-Principles Investigations on the Semiconductor-to-Metal Phase Transition of 2D Si 2 Te 3 for Reversible Resistive Switching.

Si 2 Te 3 is attracting attention due to its compatibility with Si technology while still showing advantages as a two-dimensional layered material. Although recent experimental studies have observed the resistive switching process in Si 2 Te 3 -based memristors, the mechanism has not been clearly identified. In this study, first-principles density functional theory calculations are employed to understand the relationship between the phase transition of Si 2 Te 3 and the reversible resistive switching of the Si 2 Te 3 -based memristor. Our calculation results show that although semiconducting Si 2 Te 3 is energetically more stable than two metallic Si 2 Te 3 phases (α and β), two metallic Si 2 Te 3 can be energetically stabilized by excess holes. The enhanced energetic preference of two metallic Si 2 Te 3 by excess holes is explained by the reduced occupation of antibonding states between Si and Te. Our study finds that the energy barrier for the phase transition between semiconducting Si 2 Te 3 and α-metallic Si 2 Te 3 varies significantly by excess charge carriers so the phase transition can be directly connected to the reversible resistive switching of the Si 2 Te 3 -based memristor under external bias. Our finding will serve as a cornerstone for optimizing the resistive switching process of the Si 2 Te 3 -based memristor.