Effect of Deposition Pressure on the Microstructure and Optical Band Gap of Molybdenum Disulfide Films Prepared by Magnetron Sputtering

Gong Gong,Xiao Xiao,Zhu Zhu,Ma Ma,Wang Wang

doi:10.3390/coatings9090570

Abstract

MoS2 films were prepared via magnetron sputtering under different deposition pressures, and the effects of deposition pressure on the crystal structure, surface morphology, and optical properties of the resulting films were investigated. The results show that the crystallinity of the films first increases and then decreases with increasing pressure. The surface of the films prepared by magnetron sputtering is dense and uniform with few defects. The deposition pressure affects the grain size, surface morphology, and optical band gap of the films. The films deposited at a deposition pressure of 1 Pa revealed remarkable crystallinity, a 30.35 nm grain size, and a 1.67 eV optical band gap. Given the large electronegativity difference between MoS2 molecules and weak van der Waals forces between layers, the MoS2 films are prone to defects at different deposition pressures, causing the exciton energy near defects to decrease and the modulation of the surrounding band.

Highlights

Advances in technology have increased the demand for various materials, and optoelectronic materials with adjustable band gaps and high stability have become research hotspots [1,2,3]
The surface morphology and roughness of the films were determined by atomic force microscopy (AFM; Nitegra Prima SPM, NT-MDT Spectrum Instruments, Moscow, Russia)
The X-ray diffraction (XRD) spectra of MoS2 films prepared on the silicon substrate are shown in Figure 1; here, two peaks at 69.4◦ and 69.6◦ were found

Summary

Introduction

Advances in technology have increased the demand for various materials, and optoelectronic materials with adjustable band gaps and high stability have become research hotspots [1,2,3]. First-principles calculations have been used to determine the crystal band structure of MoS2 , and band gaps of 1.2–1.8 eV have been identified [24,25,26,27]. MoS2 films may be prepared using magnetron sputtering and chemical vapor deposition, among other methods, and optical band gaps in the range of 1.2 to 1.9 eV have been produced [20,28,29,30]. The optical properties of MoS2 have been extensively reported, the mechanism through which crystal structure changes, caused by the pressure parameters of magnetron sputtering, remains unknown. Further exploration of the preparation technology and performance of MoS2 films is necessary. MoS2 films were prepared under different sputtering pressures, and the structural and optical properties of the resulting films were tested.

Preparation of MoS2 Films

Characterization of MoS2 Films

Results and Discussion

Photoluminescence

Conclusions