Study of the Synthesis Process of MoO3 to MoS2 Thin Films Deposited by Spray Pyrolysis: The Effect of [S/Mo] Mole Concentration and Sulfurization Process

• Published in: Journal of electronic materials Vol. 50; no. 6; pp. 3341 - 3347
• Main Authors: Faraji, S., Bagheri-Mohagheghi, M.-M., Mousavi, M.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.06.2021; Springer Nature B.V
• Subjects: Argon; Characterization and Evaluation of Materials; Chemistry and Materials Science; Crystal structure; Electronics and Microelectronics; Energy bands; Energy gap; Glass substrates; Grain size; Instrumentation; Materials Science; Molybdenum; Molybdenum disulfide; Molybdenum oxides; Molybdenum trioxide; Morphology; Optical and Electronic Materials; Optical properties; Original Research Article; Preferred orientation; Scanning electron microscopy; Solid State Physics; Spray pyrolysis; Sulfurization; Thin films; Ultraviolet spectra; X-ray diffraction; MoS; Semiconductors; MoO; spray pyrolysis; thin films
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-021-08826-7

In this paper, molybdenum disulfide (MoS 2 ) thin films were deposited using an initial solution of molybdenum trioxide (MoO 3 ) and thiourea (SC(NH 2 ) 2 ) on glass substrate with various mole concentrations by spray pyrolysis. The films were deposited in two steps (a) [S/ Mo] mole concentration ratio (x) varied at values of 0, 1, 2, 3, 5 and 10 at substrate temperature of T s = 400ºC and (b) under post sulfurization process in the presence of argon gas at an annealing temperature of T a = 450ºC. We applied x-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet-visible (UV-Vis) spectra for characterization of the MoS 2 thin films in terms of morphology, crystal structure and optical properties. The effect of [S/Mo] mole concentration ratio and post sulfurization processes on the structural conversion, morphology, x-ray diffraction and optical properties of these films have been studied. In non-sulfurization conditions it is found that the films are polycrystalline with a MoO 3 single phase and in post sulfurization conditions have hexagonal crystal structure corresponding to MoS 2 phase with preferred orientation along the (002) plane. The intensity of peaks increased with sulfurization and increase of mole concentration. The morphology of films obtained by scanning electron microscopy (SEM) appears as bar-shaped nano-grains. The average grain size increases with increasing mole concentration of S, in solution. Optical transparency of films changed in the range of 20% to 50% and 20% to 5%, in the visible region before and after sulfurization, respectively. The energy band gap ( E g ) of films hardly depends to post sulfurization process, band gap decreased from 3.2 eV to 1.2 eV.