2020Frontiers of Physics

Bandgap opening in MoTe₂ thin flakes induced by surface oxidation

Yuan Gan, Jiyuan Liang, Chang-woo Cho, Si Li, Yanping Guo, Xiaoming Ma, Xuefeng Wu, Jinsheng Wen, Xu Du, Mingquan He, Chang Liu, Shengyuan A. Yang, Kedong Wang, Liyuan Zhang

Frontiers of Physics · 15, 33602 (2020)

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DOI 10.1007/s11467-020-0952-x

**AI thematic illustration**Concept artwork created for this paper.

Introduction

Transport, scanning tunnelling microscopy and calculations examine 1T′-MoTe₂ as it is thinned. Unprotected flakes develop insulating behaviour, whereas samples protected with hexagonal boron nitride display a superconducting transition. The comparison points to a role for surface oxidation.

A closer reading

Encapsulation provides a key control because thinning and exposure can both change a transport curve. Varying the protection tests an alternative explanation for the apparent metal-to-insulator change rather than automatically assigning it to reduced dimensionality.