Reversible Structural Transition of Two-Dimensional Copper Selenide on Cu(111)

TL;DR

This study demonstrates a reversible structural transition in honeycomb CuSe monolayers on Cu(111), controlled by Se coverage and annealing temperature, with implications for tuning 2D material properties.

Contribution

We reveal a reversible structural transition in CuSe monolayers on Cu(111), advancing understanding of 2D material manipulation through controlled synthesis and thermal treatment.

Findings

Reversible transition between stripe-CuSe and hole-CuSe structures.

Se content and annealing temperature govern the structural phases.

STM and AES confirm the structural and compositional changes.

Abstract

Structural engineering opens a door to manipulating the structures and thus tuning the properties of two-dimensional materials. Here, we report a reversible structural transition in honeycomb CuSe monolayer on Cu(111) through scanning tunneling microscopy (STM) and Auger electron spectroscopy (AES). Direct selenization of Cu(111) gives rise to the formation of honeycomb CuSe monolayers with 1D moir\'e structures (stripe-CuSe), due to the asymmetric lattice distortions in CuSe induced by the lattice mismatch. Additional deposition of Se combined with post annealing results in the formation of honeycomb CuSe with quasi-ordered arrays of triangular holes (hole-CuSe), namely, the structural transition from stripe-CuSe to hole-CuSe. Further, annealing the hole-CuSe at higher temperature leads to the reverse structural transition, namely from hole-CuSe to stripe-CuSe. AES measurement unravels the Se content change in the reversible structural transition. Therefore, both the Se coverage and annealing temperature play significant roles in the reversible structural transition in CuSe on Cu(111). Our work provides insights in understanding of the structural transitions in 2D materials.