Versatile and Scalable Strategy To Grow Sol–Gel Derived 2H-MoS₂ Thin Films with Superior Electronic Properties: A Memristive Case

Abstract

Transition metal dichalcogenides, such as molybdenum disulfide (MoS₂), show peculiar chemical/physical properties that enable their use in applications ranging from micro- and nano-optoelectronics to surface catalysis, gas and light detection, and energy harvesting/production. One main limitation to fully harness the potential of MoS₂ is given by the lack of scalable and low environmental impact synthesis of MoS₂ films with high uniformity, hence setting a significant challenge for industrial applications. In this work, we develop a versatile and scalable sol-gel-derived MoS₂ film fabrication by spin coating deposition of an aqueous sol on different technologically relevant, flexible substrates with annealing at low temperatures (300 °C) and without the need of sulfurization and/or supply of hydrogen as compared to cutting-edge techniques. The electronic and physical properties of the MoS₂ thin films were extensively investigated by means of surface spectroscopy and structural characterization techniques. Spatially homogenous nanocrystalline 2H-MoS₂ thin films were obtained exhibiting high chemical purity and excellent electronic properties such as an energy band gap of 1.35 eV in agreement with the 2H phase of the MoS₂, and a density of states that corresponds to the n-type character expected for high-quality 2H-MoS₂. The potential use of sol-gel-grown MoS₂ as the candidate material for electronic applications was tested via electrical characterization and demonstrated via the reversible switching in resistivity typical for memristors with a measured ON-OFF ratio ≥10². The obtained results highlight that the novel low-cost fabrication method has a great potential to promote the use of high-quality MoS₂ in technological and industrial-relevant scalable applications.