Formation of Ohmic contacts between ferromagnetic Cr2Ge2Te6 and two-dimensional metals

Abstract

As a ferromagnetic semiconductor, two-dimensional (2D) Cr2Ge2Te6 holds significant implications for electronic and spintronic devices. To achieve 2D electronics, it is essential to integrate Cr2Ge2Te6 with 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 Cr2Ge2Te6 with 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 Zn3C2 and Hg3C2 as 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 Cr2Ge2Te6 can 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.