Spatial defects nanoengineering for bipolar conductivity in MoS2

Xiaorui Zheng,Zhujun Huang,Carmela Aruta,Michele Vittadello,Vishal Narang,Elisa Riedo,Tengfei Cao,Francesco Lavini,Edoardo Albisetti,Annalisa Calò,William P King,Marija Drndic,Tai-De Li,Paul Masih Das,Davood Shahrjerdi,John W Harrold,Xiangyu Liu

doi:10.1038/s41467-020-17241-1

Abstract

Understanding the atomistic origin of defects in two-dimensional transition metal dichalcogenides, their impact on the electronic properties, and how to control them is critical for future electronics and optoelectronics. Here, we demonstrate the integration of thermochemical scanning probe lithography (tc-SPL) with a flow-through reactive gas cell to achieve nanoscale control of defects in monolayer MoS2. The tc-SPL produced defects can present either p- or n-type doping on demand, depending on the used gasses, allowing the realization of field effect transistors, and p-n junctions with precise sub-μm spatial control, and a rectification ratio of over 104. Doping and defects formation are elucidated by means of X-Ray photoelectron spectroscopy, scanning transmission electron microscopy, and density functional theory. We find that p-type doping in HCl/H2O atmosphere is related to the rearrangement of sulfur atoms, and the formation of protruding covalent S-S bonds on the surface. Alternatively, local heating MoS2 in N2 produces n-character.

Highlights

Understanding the atomistic origin of defects in two-dimensional transition metal dichalcogenides, their impact on the electronic properties, and how to control them is critical for future electronics and optoelectronics
To understand the evolution of the work-function variation in N2-thermochemical scanning probe lithography (tc-SPL) doping, we investigate ΔΦKPFM for chemical vapor deposition (CVD) monolayer MoS2 as a function of the absolute tc-SPL heater temperature (Fig. 5a, for scan rate = 0.2 μm s−1), which is fitted according to Eq (1)
We show that tc-SPL patterning is a strategy for the design with precise size and spatial control of electronic p–n junctions in monolayer MoS2, where a current rectifying ratio of over 104 is observed

Summary

Introduction

Understanding the atomistic origin of defects in two-dimensional transition metal dichalcogenides, their impact on the electronic properties, and how to control them is critical for future electronics and optoelectronics. Examples include bandgap engineering in TMDCs alloys[3], substitutional doping at defects sites[4], spatial control of thickness[5] or of crystalline phases[6], and the growth of different laterally or vertically aligned TMDCs to form heterojunctions[7]. Most of these methods are not scalable and it remains challenging to pattern with sub-μm resolution both n-type and p-type character within the same 2D material[8,9,10]. A comprehensive understanding of defects would be beneficial to find strategies to heal their detrimental effects[25], and to postpone defect-induced sample degradation over time[26]

Methods

Results

Conclusion