A Metastable Pentagonal 2D Material Synthesized by Symmetry-Driven Epitaxy

TL;DR

This paper reports the successful synthesis and characterization of a metastable pentagonal 2D material, monolayer pentagonal PdTe2, using symmetry-driven epitaxy, revealing its semiconducting properties and potential for nanoelectronics.

Contribution

The study demonstrates the first experimental synthesis of a metastable pentagonal 2D material, monolayer pentagonal PdTe2, via symmetry-driven epitaxy, expanding the family of 2D materials beyond hexagonal structures.

Findings

Monolayer pentagonal PdTe2 is a well-ordered, metastable 2D material.

It exhibits an indirect bandgap of 1.05 eV.

The material's structure is stabilized by lattice matching with Pd(100).

Abstract

Most two-dimensional (2D) materials experimentally studied so far have hexagons as their building blocks. Only a few exceptions, such as PdSe2, are lower in energy in pentagonal phases and exhibit pentagons as building blocks. While theory has predicted a large number of pentagonal 2D materials, many of them are metastable and their experimental realization is difficult. Here we report the successful synthesis of a metastable pentagonal 2D material, the monolayer pentagonal PdTe2, by symmetry-driven epitaxy. Scanning tunneling microscopy and complementary spectroscopy measurements are used to characterize the monolayer pentagonal PdTe2, which demonstrates well-ordered low-symmetry atomic arrangements and is stabilized by lattice matching with the underlying Pd(100) substrate. Theoretical calculations, along with angle-resolved photoemission spectroscopy, reveal monolayer pentagonal PdTe2 is a semiconductor with an indirect bandgap of 1.05 eV. Our work opens an avenue for the synthesis of pentagon-based 2D materials and gives opportunities to explore their applications such as multifunctional nanoelectronics.