Semiconducting Silicene: A Two-Dimensional Silicon Allotrope with Hybrid Honeycomb-Kagome Lattice

Silicene is recognized as a promising candidate of two-dimensional (2D) materials replacing bulk silicon in the post-CMOS era, because of its compatibility with silicon-based technologies. However, the Dirac-cone band structure, because of the honeycomb lattice, prevents pristine silicene from being applied as a semiconductor in electronic devices. Here, we propose a 2D-silicon semiconductor by introducing kagome topology into the honeycomb lattice, i.e., a hybrid honeycomb-kagome (hhk) structure that is referenced as hhk-silicene. Our first-principles calculations demonstrate the high geometric stability and excellent semiconducting properties of the hhk-silicene, which opens up an electronic bandgap comparable to that of the bulk silicon and bears an electron mobility as high as that of the honeycomb silicene. By designing a field-effect transistor based on the hhk-silicene, giant negative differential resistance and switching performance fulfilling the requirements of ITRS (International Technology Roadmap for Semiconductors) are predicted. This work opens up the possibility of rational design of 2D-silicon semiconductors by focusing on the topological lattice structures.