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 MX 2 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 Cu 2 Te crystal could be synthesized by one-step liquid−solid interface growth and exfoliation. Characterizations of atomically resolved scanning tunneling microscope reveal that the Cu 2 Te monolayer consists of two lattice-matched distinct phases, similar to the 1T and 1T′ phases of MX 2 . The scanning tunneling spectra identify the coexistence of the metallic 1T and semiconducting 1T′ phases within the chemically homogeneous Cu 2 Te 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 atomicscale electronic devices in 2D materials.

Achieving Ultralow Lattice Thermal Conductivity and High Thermoelectric Performance in GeTe Alloys via Introducing Cu2Te Nanocrystals and Resonant Level Doping

“…It is worth it to note that the Ge phase disappears after introducing In and Cu elements. We deduced that Cu doping promotes Ge dissolving. , XPS (X-ray photoemission spectroscopy) high-resolution spectra (Figure c,d) indicates the existence of Cu 1+ . The lattice expansion can be attributed to the reduced vacancy concentration and the bigger ionic radii of Cu 1+ (0.77 Å) and In 3+ (0.8 Å) in contrast to Ge 2+ (0.73 Å) .…”

“…45,59 XPS (X-ray photoemission spectroscopy) high-resolution spectra (Figure 1c,d) indicates the existence of Cu 1+ . 66 The lattice expansion can be attributed to the reduced vacancy concentration and the bigger ionic radii of Cu 1+ (0.77 Å) and In 3+ (0.8 Å) in contrast to Ge 2+ (0.73 Å). 45 The impurity peak of Cu 2 Te can be detected as the Cu doping level is above 10%.…”

High‐Performance Memristors Based on Ultrathin 2D Copper Chalcogenides

“…Recently, the classical hexagonal Nowotny model (P6/mmm symmetry) of Cu 2 Te has been considered energetically unfavorable, and its other low-energy optimized Nowotny model structures have been proposed. [6,14] Here, based on our experimental results and previous reports about Cu 2 Te, we adopted a hexagonal structure with a rectangular unit cell, as shown in Figure 1b,c-i. The lattice constants are a = 7.17 Å, b = 4.14 Å, and c = 7.25 Å (corresponding to single layer thickness).…”

“…As can be seen from the side view, each Cu 2 Te layer comprises six atomic layers: that is, two outermost buckled Te layers and four middle Cu layers. [ 14 ] Theoretical calculations indicate that such buckled structure is dynamically and thermally stable for it has lower total energy than planar structure. [ 37 ] Recent research also proved that Cu 2 Te has good environmental stability, showing great potential in practical applications.…”

“…For Cu 2 Te nanosheet, the interplanar distance between lattice fringes is measured to be 0.36 nm, matching well with the (200) plane of the expected Cu 2 Te corrugate structure. [14,16] The lattice spacing of CuSe nanosheet is calculated to be 0.19 nm, corresponding to its (110) plane spacing (PDF No. 34-0171).…”