Lattice-Matched Metal-Semiconductor Heterointerface in Monolayer Cu₂Te.

Abstract

The interface between metals and semiconductors plays an essential role in two-dimensional electronic heterostructures, which has provided an alternative opportunity to realize next-generation electronic devices. Lattice-matched two-dimensional heterointerfaces have been achieved in polymorphic 2D transition-metal dichalcogenides MX₂ with M = (W, Mo) and X = (Te, Se, S) through phase engineering; yet other transition-metal chalcogenides have been rarely reported. Here we show that a single layer of hexagonal Cu₂Te crystal could be synthesized by one-step liquid-solid interface growth and exfoliation. Characterizations of atomically resolved scanning tunneling microscope reveal that the Cu₂Te monolayer consists of two lattice-matched distinct phases, similar to the 1T and 1T' phases of MX₂. The scanning tunneling spectra identify the coexistence of the metallic 1T and semiconducting 1T' phases within the chemically homogeneous Cu₂Te crystals, as confirmed by density functional theory calculations. Moreover, the two phases could form nanoscale lattice-matched metal-semiconductor junctions with atomically sharp interfaces. These results suggest a promising potential for exploiting atomic-scale electronic devices in 2D materials.