Correlating the Electronic Structures of Metallic/Semiconductor MoTe2 Interface to its Atomic Structures

TL;DR

This study investigates the atomic and electronic structures at the phase boundary of MoTe2, revealing how these properties influence device performance and offering insights for phase boundary engineering in 2D materials.

Contribution

It provides a detailed correlation between atomic structures and electronic properties at MoTe2 phase boundaries using advanced microscopy and calculations, which is novel.

Findings

Excitonic peaks cross the phase boundary within ~150 nm.

Crystal field extends ~2 unit cells into the opposite phase.

Plasmonic oscillations show angle-dependent red-shifts at boundaries.

Abstract

Contact interface properties are important in determining the performances of devices based on atomically thin two-dimensional (2D) materials, especially those with short channels. Understanding the contact interface is therefore quite important to design better devices. Herein, we use scanning transmission electron microscopy, electron energy loss spectroscopy, and first-principles calculations to reveal the electronic structures within the metallic (1T')-semiconducting (2H) MoTe2 coplanar phase boundary across a wide spectral range and correlate its properties and atomic structure. We find that the 2H-MoTe2 excitonic peaks cross the phase boundary into the 1T' phase within a range of approximately 150 nm. The 1T'-MoTe2 crystal field can penetrate the boundary and extend into the 2H phase by approximately two unit cells. The plasmonic oscillations exhibit strong angle dependence, i.e., a red-shift (approximately 0.3 eV-1.2 eV) occurs within 4 nm at 1T'/2H-MoTe2 boundaries with large tilt angles, but there is no shift at zero-tilted boundaries. These atomic-scale measurements reveal the structure-property relationships of 1T'/2H-MoTe2 boundary, providing useful information for phase boundary engineering and device development based on 2D materials.