Hole doping effect of MoS2 via electron capture of He+ ion irradiation

Sang Wook Han,Hyesun Kim,Won Seok Yun,Chang Won Ahn,D.-H Kim,Yanghee Kim,Sunmin Ryu

doi:10.1038/s41598-021-02932-6

Abstract

Beyond the general purpose of noble gas ion sputtering, which is to achieve functional defect engineering of two-dimensional (2D) materials, we herein report another positive effect of low-energy (100 eV) He+ ion irradiation: converting n-type MoS2 to p-type by electron capture through the migration of the topmost S atoms. The electron capture ability via He+ ion irradiation is valid for supported bilayer MoS2; however, it is limited at supported monolayer MoS2 because the charges on the underlying substrates transfer into the monolayer under the current condition for He+ ion irradiation. Our technique provides a stable and universal method for converting n-type 2D transition metal dichalcogenides (TMDs) into p-type semiconductors in a controlled fashion using low-energy He+ ion irradiation.

Highlights

The photoemission and work function (WF) measurements have shown p-doping shifts of the Fermi energy ( EF) from the bulk to bilayer MoS2 surfaces by H e+ ion irradiation
Unlike the approach employing defect engineering of 2D transition metal dichalcogenides (TMDs) using high-energy noble gas ion sputtering, we report another positive effect of low-energy (100 eV) H e+ ion irradiation that can be highly tuned to capture accumulated excess electrons on the n-type MoS2 surfaces
We investigated the inevitably air-exposed M oS2 samples to elucidate the influences of the H e+ ion irradiation on the work function (WF) values, structural properties, and bandgap changes

Summary

Introduction

The photoemission and work function (WF) measurements have shown p-doping shifts of the Fermi energy ( EF) from the bulk to bilayer MoS2 surfaces by H e+ ion irradiation. The H e+ ion irradiation on the p-type M oS2 surface reversely shifted the photoemission spectra toward the high binding energy side (Fig. 3d).

Results

Conclusion