Van der Waals (vdWs) stacking of two-dimensional (2D) materials can effectively weaken the Fermi level pinning (FLP) effect in metal/semiconductor contacts due to dangling-bond-free surfaces. However, the inherent vdW...Van der Waals (vdWs) stacking of two-dimensional (2D) materials can effectively weaken the Fermi level pinning (FLP) effect in metal/semiconductor contacts due to dangling-bond-free surfaces. However, the inherent vdWs gap always induces a considerable tunneling barrier, significantly limiting carrier injection. Herein, by inducing a sp^(2) to sp^(3) hybridization transformation in 2D carbon-based metal via surface defect engineering, the large orbital overlap can form an efficient carrier channel, overcoming the tunneling barrier. Specifically, by selecting the 2D carbon-based X_(3)C_(2) (X = Cd, Hg, and Zn) metal and the 2D MSi_(2)N_(4) (M = Cr, Hf, Mo, Ti, V, and Zr) semiconductor, we constructed 36 metal/semiconductor contacts. For vdWs contacts, although Ohmic contacts can be formed at the interface, the highest tunneling probability (P TB) is only 3.11%. As expected, the P TB can be significantly improved, as high as 48.73%, when MSi_(2)N_(4), accompanied by surface nitrogen vacancies, forms an interface covalent bond with X_(3)C_(2). Simultaneously, weak FLP and Ohmic contact remain at the covalent-bond-based surface, attributing to the protection of the MSi_(2)N_(4) band-edge electronic states by the outlying Si-N sublayer. Our work provides a promising path for advancing the progress of 2D electronic and photoelectronic devices.展开更多
基金supported by China Postdoctoral Science Foundation(No.2022M711691)the National Natural Science Foundation of China(Nos.12104130 and 12304085)+3 种基金Six talent peaks project in Jiangsu Province(No.XCL-104)the open research fund of Key Laboratory of Quantum Materials and Devices(Southeast University)Ministry of Education(No.3207022401C3)Natural Science Foundation of Nanjing University of Posts and Telecommunications(No.NY221102).
文摘Van der Waals (vdWs) stacking of two-dimensional (2D) materials can effectively weaken the Fermi level pinning (FLP) effect in metal/semiconductor contacts due to dangling-bond-free surfaces. However, the inherent vdWs gap always induces a considerable tunneling barrier, significantly limiting carrier injection. Herein, by inducing a sp^(2) to sp^(3) hybridization transformation in 2D carbon-based metal via surface defect engineering, the large orbital overlap can form an efficient carrier channel, overcoming the tunneling barrier. Specifically, by selecting the 2D carbon-based X_(3)C_(2) (X = Cd, Hg, and Zn) metal and the 2D MSi_(2)N_(4) (M = Cr, Hf, Mo, Ti, V, and Zr) semiconductor, we constructed 36 metal/semiconductor contacts. For vdWs contacts, although Ohmic contacts can be formed at the interface, the highest tunneling probability (P TB) is only 3.11%. As expected, the P TB can be significantly improved, as high as 48.73%, when MSi_(2)N_(4), accompanied by surface nitrogen vacancies, forms an interface covalent bond with X_(3)C_(2). Simultaneously, weak FLP and Ohmic contact remain at the covalent-bond-based surface, attributing to the protection of the MSi_(2)N_(4) band-edge electronic states by the outlying Si-N sublayer. Our work provides a promising path for advancing the progress of 2D electronic and photoelectronic devices.
