New submonolayer copper telluride phase on Cu(111) -- ad-chain and trough formation

TL;DR

This paper reports the discovery and detailed structural characterization of a new submonolayer copper telluride phase on Cu(111), revealing unique ad-chain and trough formations with perfect long-range order.

Contribution

It introduces a novel $ extless 5 imes extless extsqrt{3} extgreater extgreater$ copper telluride phase with comprehensive experimental and theoretical analysis confirming its structure and stability.

Findings

Identified a new ordered copper telluride phase on Cu(111).

Structural model verified by LEED-IV and DFT with low R-factor.

Phase is the densest possible before bulk growth begins.

Abstract

We present a so far undetected submonolayer phase of copper telluride on Cu(111) with $\left(5 \times \sqrt{3}\right)_{\text{rect}}$ periodicity and coverage of 0.40 ML Tellurium (Te), which can be grown with perfect long-range order. It is structurally characterized by a combination of quantitative low-energy electron diffraction (LEED-IV), scanning tunneling microscopy (STM), and density functional theory (DFT). We find that Te induces the formation of four atom wide linear troughs within the Cu(111) surface filled up by two Te atoms per unit cell. Additionally, the interspace between the troughs is decorated by Cu$_2$Te$_2$ ad-chains sitting at hcp sites. All Te atoms exhibit the same local sixfold coordination: They occupy threefold hollow sites of the substrate and are one-sided attached to another three Cu atoms. The presented structural model is verified by a LEED-IV analysis with Pendry R-factor of R = 0.174 and quantitative agreement of structural parameters with DFT predictions. It also has by far the lowest energy of all models tested by DFT and simulated STM images agree perfectly with experiment. It turns out that the new $\left(5 \times \sqrt{3}\right)_{\text{rect}}$ phase is the most dense surface telluride phase possible on Cu(111) before bulk-like copper telluride starts to growth.