An Effective Route for the Growth of Multilayer MoS2 by Combining Chemical Vapor Deposition and Wet Chemistry

Ziyad M Almohaimeed,Saira Sarwar,Ahmet Oral,Rizwan Akram,Shumaila Karamat,Asad Javaid,Da-Ren Hang

doi:10.1155/2022/3233252

Abstract

Molybdenum disulfide (MoS2) is an actively pursuing material of the 2D family due to its semiconducting characteristics, making it a potential candidate for nano and optoelectronics application. MoS2 growth from molybdenum and sulphur precursors by chemical vapor depositions (CVD) is used widely, but molybdates’ conversion into MoS2 via CVD is overlooked previously. Direct growth of MoS2 on the desired pattern not only reduces the interfacial defects but also reduces the complexities in device fabrication. In this work, we combine the wet synthesis and chemical vapor deposition method where sodium molybdate and L-cysteine are used to make a solution. With the dip coating, the mixture is coated on the substrates, and then, chemical vapor deposition is used to convert the chemicals into MoS2. Raman spectroscopy revealed the presence of oxysulphides (peaks number value) other than A 1 g and E 2 g 1 , where heat treatment was performed in the presence of Ar gas flow only. On the other hand, the films reducing in the presence of sulphur and argon gas promote only A 1 g and E 2 g 1 peaks of MoS2, which confirms complete transformation. XRD diffraction showed a very small change in the diffraction peaks and value of strain, whereas SEM imaging showed the flakes formation for MoS2 samples which were heated in the presence of sulphur. X-ray photoelectron spectroscopy is also performed for the chemical composition and to understand the valence state of Mo, S, and O and other species.

Highlights

Transition metal dichalcogenides (TMDs) garner attention due to their potential in practical applications [1,2,3,4,5,6]. e physical and electronic properties of these 2D layered materials gave them credit for an exceptional class of materials
Van der Waals forces stack covalently bound MoS2 (S-Mo-S) in binary MX2-layered materials [15]. In bulk form, it has an indirect band gap of 1.2 eV, which increases as the number of layers decreases due to the quantum confinement effect, reaching direct 1.9 eV band gap for the MoS2 monolayer [16]
The samples are transferred to the chemical vapor depositions (CVD) chamber, where the substrate was kept in the tube centre

Summary

Research Article

MoS2 growth from molybdenum and sulphur precursors by chemical vapor depositions (CVD) is used widely, but molybdates’ conversion into MoS2 via CVD is overlooked previously. We combine the wet synthesis and chemical vapor deposition method where sodium molybdate and L-cysteine are used to make a solution. Raman spectroscopy revealed the presence of oxysulphides (peaks number value) other than A1g and E12g, where heat treatment was performed in the presence of Ar gas flow only. The films reducing in the presence of sulphur and argon gas promote only A1g and E12g peaks of MoS2, which confirms complete transformation. XRD diffraction showed a very small change in the diffraction peaks and value of strain, whereas SEM imaging showed the flakes formation for MoS2 samples which were heated in the presence of sulphur. X-ray photoelectron spectroscopy is performed for the chemical composition and to understand the valence state of Mo, S, and O and other species

Introduction

Materials and Methods

Results and Discussion

Vacuum Pump