Multilayer silicene: clear evidence of Ag-terminated bulk silicon

Abstract

The existence of silicite, a new allotrope of silicon based on a stacking of hexagonal silicene planes, is one of the most discussed topics in the field of two-dimensional materials. Using grazing incidence x-ray diffraction (GIXD), we have followed the in situ growth of Si films on Ag(1 1 1) in the low-temperature growth regime (510–520 K). GIXD experiments demonstrate that Si films have a diamond-like structure, with an average lattice constant slightly different from that of bulk Si. The diffracted intensities associated with Si films are well reproduced by the Ag/Si(1 1 1) honeycomb chain model, whereas models with Ag-free Si surfaces fail to reproduce the experimental data.