Synthesis of MoS2 Thin Film by Ionized Jet Deposition: Role of Substrate and Working Parameters

Amir Ghiami,Melanie Timpel,Marco Vittorio Nardi,Andrea Chiappini,Roberto Verucchi

doi:10.3390/surfaces3040045

Abstract

The lack of scalable synthesis of transition metal dichalcogenides, such as molybdenum disulfide (MoS2), has proved to be a significant bottleneck in realization of fundamental devices and has hindered the commercialization of these materials in technologically relevant applications. In this study, a cost-efficient and versatile thin-film fabrication technique based on ionized jet deposition (IJD), i.e., a technique potentially providing high processing efficiency and scalability, is used to grow MoS2 thin films on silicon substrates. The operating conditions of IJD were found to influence mainly the ablation efficiency of the target and only slightly the quality of the deposited MoS2 thin film. All as-deposited films show chemical properties typical of MoS2 with an excess of free, elemental sulfur that can be removed by post-deposition annealing at 300–400 °C, which also promotes MoS2 crystallization. The formation of an interface comprised of several silicon oxide species was observed between MoS2 and the silicon substrate, which is suggested to originate from etching and oxidizing processes of dissociated water molecules in the vacuum chamber during growth. The present study paves the way to further design and improve the IJD approach for TMDC-based devices and other relevant technological applications.

Highlights

MoS2 thin films were grown on native oxide-covered silicon substrates (SiO2 /Si) using a novel up-scalable pulsed electron deposition technique; namely, ionized jet deposition (IJD) [18,19,20]
We present an original MoS2 synthesis approach based on IJD, a technique that could lead to transition metal dichalcogenides (TMDCs) synthesis compatible with large scale production
Among the different working conditions, we identified 15 kV acceleration voltage and 150 Hz deposition frequency as the best MoS2 growth parameters

Summary

Introduction

Two-dimensional transition metal dichalcogenides (TMDCs) such as MoS2 , WS2 , MoSe2 , and NbSe2 have recently attracted enormous technological and scientific interest due to their remarkable mechanical, electronic, and optical properties that greatly differ from their bulk counterparts [1,2,3].For instance, owing to their tunable band gap by varying the number of layers, laboratory-scaleTMDC-based electronic devices such as transistors [4,5], sensors [6,7], memristors [8,9], etc. have been demonstrated using few or single-layer materials, and the outcome sparked hopes to obtain highly efficient electronic devices beyond silicon-based technology. Surfaces 2020, 3 methods [10,11,12], chemical vapor deposition (CVD) [13], wet-chemistry approaches [14,15], pulsed laser deposition (PLD) [16], and magnetron sputtering [17]. Most of these techniques still lack industrial scalability for simple and low-cost production of MoS2 with uniform and reproducible material properties. MoS2 thin films were grown on native oxide-covered silicon substrates (SiO2 /Si) using a novel up-scalable pulsed electron deposition technique; namely, ionized jet deposition (IJD) [18,19,20]

Methods

Results

Discussion

Conclusion