Electronic structure and exciton shifts in Sb-doped MoS2 monolayer

Mianzeng Zhong,Guozhen Shen,Hui-Xiong Deng,Zhongming Wei,Le Huang,Houzhi Zheng,Jingbo Li,Chao Shen

doi:10.1038/s41699-018-0083-1

Abstract

The effective manipulation of excitons is important for the realization of exciton-based devices and circuits, and doping is considered a good strategy to achieve this. While studies have shown that 2D semiconductors are ideal for excitonic devices, preparation of homogenous substitutional foreign-atom-doped 2D crystals is still difficult. Here we report the preparation of homogenous monolayer Sb-doped MoS2 single crystals via a facile chemical vapor deposition method. A and B excitons are observed in the Sb-doped MoS2 monolayer by reflection magnetic circular dichroism spectrum measurements. More important, compared with monolayer MoS2, the peak positions of two excitons show obvious shifts. Meanwhile, the degeneration of A exciton is also observed in the monolayer Sb-doped MoS2 crystal using photoluminescence spectroscopy, which is ascribed to the impurity energy levels within the band-gap, confirmed by density function theory. Our study opens a door to developing the doping of 2D layered transition metal dichalcogenides with group-V dopants, which is helpful for the fundamental study of the physical and chemical properties of transition metal dichalcogenides.

Highlights

IntroductionThe large exciton binding energy and long exciton diffusion length make the two-dimensional (2D) semiconductors become an ideal system for realizing the practical exciton-based devices operating at room-temperature.[1,2] Among them, 2D MoS2 as a typically layered transition metal dichalcogenides (TMDCs) has received increasing attention due to its unique physical and chemical properties, and potential applications in electronic and optical fields.[3,4,5] Especially, the theories and experiments have shown that monolayer MoS2 has more attractive properties than its bulk form.[6,7,8,9,10,11] For example, a direct band gap,[6,8] valley Halleffect,[7,9] and the inversion symmetry breaking have been observed in monolayer MoS2.10,11 Many methods have developed to synthesize monolayer MoS2, among them the most efficient methods are liquid phase exfoliation, mechanical exfoliation, and chemical vapor deposition.[12,13,14] Very recently, the monolayerMoS2, which synthesized by the mechanical exfoliated method, based field effect transistors show a high electronic mobility up to 200 cm2/V·s at room temperature, a large on/off current ratio of about 108, and low standby power dissipation.[13]
These all spots with different intensities correspond to Sb, Mo, and S atoms, respectively, which can be further confirmed by the experimental intensity profile (Fig. 1e)
To understand the differences between monolayer MoS2 and Sbdoped MoS2 in PL and reflection magnetic circular dichroism (RMCD) spectra, their electronic band structures are investigated by density functional theory (DFT) calculations

Summary

Introduction

The large exciton binding energy and long exciton diffusion length make the two-dimensional (2D) semiconductors become an ideal system for realizing the practical exciton-based devices operating at room-temperature.[1,2] Among them, 2D MoS2 as a typically layered transition metal dichalcogenides (TMDCs) has received increasing attention due to its unique physical and chemical properties, and potential applications in electronic and optical fields.[3,4,5] Especially, the theories and experiments have shown that monolayer MoS2 has more attractive properties than its bulk form.[6,7,8,9,10,11] For example, a direct band gap,[6,8] valley Halleffect,[7,9] and the inversion symmetry breaking have been observed in monolayer MoS2.10,11 Many methods have developed to synthesize monolayer MoS2, among them the most efficient methods are liquid phase exfoliation, mechanical exfoliation, and chemical vapor deposition.[12,13,14] Very recently, the monolayerMoS2, which synthesized by the mechanical exfoliated method, based field effect transistors show a high electronic mobility up to 200 cm2/V·s at room temperature, a large on/off current ratio of about 108, and low standby power dissipation.[13]. It is hardly applicable to the large-scale practical devices, due to the low-yield and poor controllability of the mechanical exfoliation technology.[3]

Methods

Results

Conclusion