Two-dimensional Cu₂Si sheet: a promising electrode material for nanoscale electronics

Building electronic devices on top of two-dimensional (2D) materials has recently become one of most interesting topics in nanoelectronics. Finding high-performance 2D electrode materials is one central issue in 2D nanoelectronics. In the current study, based on first-principles calculations, we compare the electronic and transport properties of two nanoscale devices. One device consists of two single-atom-thick planar Cu₂Si electrodes, and a nickel phthalocyanine (NiPc) molecule in the middle. The other device is made of often-used graphene electrodes and a NiPc molecule. Planer Cu₂Si is a new type of 2D material that was recently predicted to exist and be stable under room temperature [11]. We found that at low bias voltages, the electric current through the Cu₂Si-NiPc-Cu₂Si junction is about three orders higher than that through graphene-NiPc-graphene. Detailed analysis shows that the surprisingly high conductivity of Cu₂Si-NiPc-Cu₂Si originates from the mixing of the Cu₂Si state near Fermi energy and the highest occupied molecular orbital of NiPc. These results suggest that 2D Cu₂Si may be an excellent candidate for electrode materials for future nanoscale devices.