Formation of Ohmic contacts between ferromagnetic Cr2Ge2Te6and two-dimensional metals

Abstract

As a ferromagnetic semiconductor, two-dimensional (2D) Cr₂Ge₂Te₆holds significant implications for electronic and spintronic devices. To achieve 2D electronics, it is essential to integrate Cr₂Ge₂Te₆with 2D electrodes to form Schottky-barrier-free Ohmic contacts with enhanced carrier injection efficiency. Herein, by using first-principles calculations based on density-functional theory, we systematically investigate the structural, energetic, electronic and magnetic properties of 2D heterojunctions by combining Cr₂Ge₂Te₆with a series of 2D metals, including graphene, ZrCl, NbS₂, TaS₂, TaSe₂, Zn₃C₂, Hg₃C₂, and Zr₂N. Results show that NbS₂, TaS₂, TaSe₂, Zn₃C₂, Hg₃C₂, and Zr₂N form Ohmic contacts with Cr₂Ge₂Te₆, in contrast to graphene and ZrCl that exhibit a finite Schottky barrier. By examining the tunneling barriers and Fermi level shift, we reveal that the heterojunctions with Zn₃C₂and Hg₃C₂as electrodes exhibit advantages of both high electron injection efficiency and spin injection efficiency, for which an apparent decrease of the magnetic moment of Cr atoms in Cr₂Ge₂Te₆can be observed. These findings not only provide physical insights into the role of interfacial interaction in regulating the physical properties of 2D heterojunctions, but also pave way for the development of high-performance spintronic nanodevices for practical implementation.

Keywords: 2D heterojunctions; Cr2Ge2Te6; Ohmic contacts; Schottky barrier; interfacial interaction.