Two-Dimensional GeC₂ with Tunable Electronic and Carrier Transport Properties and a High Current ON/OFF Ratio

In this study, we present that 2D tetrahex-GeC₂ materials possess novel electronic and carrier transport properties based on density functional theory computations combined with the nonequilibrium Green's function method. We show that under the 4% (-4%) in-plane expansion (compression) along the a-direction (b-direction) of the tetrahex-GeC₂ monolayer, the bandgap can be enlarged to a desirable 1.26 eV (1.32 eV), close to that of silicon. The carrier transport properties of both the sub-10 nm tetrahex-GeC₂ monolayer and the bilayer show strong anisotropy within the bias from -1 to 1 V. The current ON (a-direction)/OFF (b-direction) ratio amounts to 10⁵ for the tetrahex-GeC₂ monolayer. A striking negative differential conductance arises with the maximum I_peak/I_valley on the order of 10⁴ under the 4% uniaxial expansion along the b-direction of the tetrahex-GeC₂ monolayer. Overall, the 2D tetrahex-GeC₂ monolayer and bilayer possess highly tunable electronic and carrier transport properties under uniaxial strain, which can be exploited for potential applications in nanoelectronics.