Coexistence of multiple silicene phases in silicon grown on Ag(111)

TL;DR

This study investigates the growth of silicene on Ag(111), revealing multiple coexisting silicene phases and complex formation behavior influenced by Si coverage and temperature, challenging the idea of single-phase monolayer formation.

Contribution

It provides the first detailed experimental evidence of multiple silicene phases coexisting on Ag(111), demonstrating the complexity of silicene growth and phase control.

Findings

Multiple silicene phases coexist on Ag(111)

The phase composition depends on Si coverage and temperature

Single-phase silicene monolayers are not achievable on Ag(111)

Abstract

Silicene, the silicon equivalent of graphene, is attracting increasing scientific and technological attention in view of the exploitation of its exotic electronic properties. This novel material has been theoretically predicted to exist as a free-standing layer in a low-buckled, stable form, and can be synthesized by the deposition of Si on appropriate crystalline substrates. By employing low-energy electron diffraction and microscopy, we have studied the growth of Si on Ag(111) and observed a rich variety of rotationally non-equivalent silicene structures. Our results highlight a very complex formation diagram, reflecting the coexistence of different and nearly degenerate silicene phases, whose relative abundance can be controlled by varying the Si coverage and growth temperature. At variance with other studies, we find that the formation of single-phase silicene monolayers cannot be achieved on Ag(111).