The Growth Mechanism of Transition Metal Dichalcogenides by using Sulfurization of Pre-deposited Transition Metals and the 2D Crystal Hetero-structure Establishment

Chong-Rong Wu,Chao-Hsin Wu,Shih-Yen Lin,Xiang-Rui Chang

doi:10.1038/srep42146

Chong-Rong Wu, Chao-Hsin Wu + Show 2 more

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https://doi.org/10.1038/srep42146

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Abstract

A growth model is proposed for the large-area and uniform MoS2 film grown by using sulfurization of pre-deposited Mo films on sapphire substrates. During the sulfurization procedure, the competition between the two mechanisms of the Mo oxide segregation to form small clusters and the sulfurization reaction to form planar MoS2 film is determined by the amount of background sulfur. Small Mo oxide clusters are observed under the sulfur deficient condition, while large-area and complete MoS2 films are obtained under the sulfur sufficient condition. Precise layer number controllability is also achieved by controlling the pre-deposited Mo film thicknesses. The drain currents in positive dependence on the layer numbers of the MoS2 transistors with 1-, 3- and 5- layer MoS2 have demonstrated small variation in material characteristics between each MoS2 layer prepared by using this growth technique. By sequential transition metal deposition and sulfurization procedures, a WS2/MoS2/WS2 double hetero-structure is demonstrated. Large-area growth, layer number controllability and the possibility of hetero-structure establishment by using sequential metal deposition and following sulfurization procedures have revealed the potential of this growth technique for practical applications.

Highlights

One of the promising TMDs for the transistor application is Molybdenum disulfide (MoS2)[6,7]
Since the transition metal precursor and the S powder are uniformly distributed onto the substrates at high growth temperature, selective growth is difficult to achieve with the traditional chemical vapor deposition (CVD) growth technique
By sequential transition metal deposition and sulfurization procedures, we have demonstrated a WS2/MoS2/WS2 double hetero-structure grown through this growth method

Summary

Introduction

One of the promising TMDs for the transistor application is Molybdenum disulfide (MoS2)[6,7]. Since the transition metal precursor and the S powder are uniformly distributed onto the substrates at high growth temperature, selective growth is difficult to achieve with the traditional CVD growth technique In this case, when dealing with more complicated 2D crystal hetero-structures, selective etching to expose contact areas for electrodes would become a necessary processing procedure for device fabrications. We believe that by repeating the sequential transition metal deposition and the sulfurization procedures, large-area and uniform TMD hetero-structures may be prepared. To achieve this goal, further investigation over the growth mechanisms of sulfurizing pre-deposited transition metal films in hot furnace is required. By sequential transition metal deposition and sulfurization procedures, we have demonstrated a WS2/MoS2/WS2 double hetero-structure grown through this growth method

Methods

Results

Conclusion