Nanopore-patterned CuSe drives the realization of PbSe-CuSe lateral heterostructure

Abstract

Monolayer PbSe has been predicted to be a two-dimensional (2D) topological crystalline insulator (TCI) with crystalline symmetry-protected Dirac-cone-like edge states. Recently, few-layered epitaxial PbSe has been grown on the SrTiO3 substrate successfully, but the corresponding signature of the TCI was only observed for films not thinner than seven monolayers, largely due to interfacial strain. Here, we demonstrate a two-step method based on molecular beam epitaxy for the growth of the PbSe-CuSe lateral heterostructure on the Cu(111) substrate, in which we observe a nanopore patterned CuSe layer that acts as the template for lateral epitaxial growth of PbSe. This further results in a monolayer PbSe-CuSe lateral heterostructure with an atomically sharp interface. Scanning tunneling microscopy and spectroscopy measurements reveal a four-fold symmetric square lattice of such monolayer PbSe with a quasi-particle band gap of 1.8 eV, a value highly comparable with the theoretical value of freestanding PbSe. The weak monolayer-substrate interaction is further supported by both density functional theory (DFT) and projected crystal orbital Hamilton population, with the former predicting the monolayer's anti-bond state to reside below the Fermi level. Our work demonstrates a practical strategy to fabricate a high-quality in-plane heterostructure, involving a monolayer TCI, which is viable for further exploration of the topology-derived quantum physics and phenomena in the monolayer limit.

26 pagres, 6 Figures

References in corpus (8)

• The electronic properties of graphene
• 2D materials and van der Waals heterostructures
• Sequential Edge-Epitaxy in 2D Lateral Heterostructures
• Structural and electronic properties of germanene on MoS${}_2$
• Intrinsically patterned two-dimensional materials for selective adsorption of molecules and nanoclusters
• Germanene termination of Ge${}_2$Pt crystals on Ge(110)
• Strain-Induced Band Engineering in Monolayer Stanene on Sb(111)
• High-Curie-temperature ferromagnetism in bilayer CrI3 on bulk semiconducting substrates

Cited by in corpus (2)

• Moiré-induced bandgap tuning by varying electric dipole in InSe/CuSe vertical heterostructure
• Native Pb vacancy defects induced p-type characteristic in epitaxial monolayer PbSe