Point defects in epitaxial silicene on Ag(111) surface

TL;DR

This study combines first-principles calculations and STM observations to analyze point defects in epitaxial silicene on Ag(111), revealing defect formation energies, signatures, and implications for improving silicene's electronic properties.

Contribution

It provides a systematic investigation of point defect morphologies, STM signatures, and defect formation energies in silicene on Ag(111), aiding defect control during synthesis.

Findings

STM signatures for various defects identified

Defect formation energies depend on superstructure

4x4 silicene is most suitable for devices

Abstract

Silicene, a counterpart of graphene, has achieved rapid development due to its exotic electronic properties and excellent compatibility with the mature silicon-based semiconductor technology. Its low room-temperature mobility of about 100 cm2V-1s-1, however, inhibits device applications such as in field-effect transistors. Generally, defects and grain boundaries would act as scattering centers and thus reduce the carrier mobility. In this paper, the morphologies of various point defects in epitaxial silicene on Ag(111) surfaces have been systematically investigated using first-principles calculations combined with experimental scanning tunneling microscope (STM) observations. The STM signatures for various defects in epitaxial silicene on Ag(111) surface are identified. In particular, the formation energies of point defects in Ag(111)-supported silicene sheets show an interesting dependence on the superstructures, which, in turn, may have implications for controlling the defect density during the synthesis of silicene. Through estimating the concentrations of various point defects in different silicene superstructures, the mystery of the defective appearance of v13*v13 silicene in experiments is revealed, and 4*4 silicene sheet is thought to be the most suitable structure for future device applications.