Exploring charge transfer and schottky barrier modulation at monolayer Ge2Sb2Te5-metal interfaces

Abstract

Abstract Monolayer Ge2Sb2Te5 exhibits great potential in non-volatile memory technology due to its excellent electronic properties and phase-change characteristics, while the fundamental nature of Ge2Sb2Te5-metal contacts has not been well understood yet. Here, we provide a comprehensive ab initio study of the electronic properties between monolayer Ge2Sb2Te5 and Pt, Pd, Au, Cu, Cr, Ag, and W contacts based on first-principles calculations. We find that the strong interaction interfaces formed between monolayer Ge2Sb2Te5 and Pt, Pd, Cr, and W contacts show chemical bonding and strong charge transfer. In contrast, no apparent chemical bonding and weak charge transfer are observed in the weak interaction interfaces formed with Au, Cu, and Ag. Additionally, our study reveals the presence of a pronounced Fermi level pinning effect between monolayer Ge2Sb2Te5 and metals, with pinning factors of S n = 0.325 and S p = 0.350 . By increasing the interlayer distance, an effective transition from n-type Ohmic contact to n-type Schottky contact is facilitated because the band edge of Ge2Sb2Te5 is shifted upwards. Our study not only provides a theoretical basis for selecting suitable metal electrodes in Ge2Sb2Te5-based devices but also holds significant implications for understanding Schottky barrier height modulation between semiconductors and metals.