Imaging and identification of point defects in PtTe2

Kuanysh Zhussupbekov,John B Mcmanus,Ainur Zhussupbekova,Paul K Hurley,Igor V Shvets,Lida Ansari,Farzan Gity,Niall Mcevoy,Cormac Ó Coileáin,Georg S Duesberg

doi:10.1038/s41699-020-00196-8

Abstract

The properties and performance of two-dimensional (2D) materials can be greatly affected by point defects. PtTe2, a 2D material that belongs to the group 10 transition metal dichalcogenides, is a type-II Dirac semimetal, which has gained a lot of attention recently due to its potential for applications in catalysis, photonics, and spintronics. Here, we provide an experimental and theoretical investigation of point defects on and near the surface of PtTe2. Using scanning tunneling microscopy and scanning tunneling spectroscopy (STS) measurements, in combination with first-principle calculations, we identify and characterize five common surface and subsurface point defects. The influence of these defects on the electronic structure of PtTe2 is explored in detail through grid STS measurements and complementary density functional theory calculations. We believe these findings will be of significance to future efforts to engineer point defects in PtTe2, which is an interesting and enticing approach to tune the charge-carrier mobility and electron–hole recombination rates, as well as the site reactivity for catalysis.

Highlights

The discovery of graphene[1] has led to increasing interest in twodimensional (2D) materials for both fundamental research[2,3,4] and hands-on applications5,6. 2D materials have a wide range of interesting properties[7], that are not always achievable or apparent in their bulk form[8]
During ex-situ transfer to ultrahigh vacuum (UHV) the sample was mounted on an STM puck
The noticeable surface contamination present likely originates from the sample being exposed to ambient conditions between synthesis and analysis

Summary

Introduction

The discovery of graphene[1] has led to increasing interest in twodimensional (2D) materials for both fundamental research[2,3,4] and hands-on applications5,6. 2D materials have a wide range of interesting properties[7], that are not always achievable or apparent in their bulk form[8]. The STM and STS experimental results are complemented and supported by DFT to probe, and understand the electronic properties of PtTe2, the characteristics of different defect types, and their impact on the electronic structure of PtTe2.

Results

Conclusion