ALD-CVD Based Synthesis and Characterization of TiS2 2D Crystals

Two-dimensional (2D) materials possess unique and often time superior electronic characteristics compared to their bulk counterparts. In parallel, large surface area and mechanical flexibility of 2D nanomaterials make them promising candidates for application in batteries, energy conversion, charge storage, and sensors. Among 2D materials, layered transition metal dichalcogenides (TMDCs) have drawn significant attention recently for their potential use in optoelectronics, spintronics, energy harvesting, and information processing. The focus of this study is to fabricate and probe the optical, transport and physical characteristics of titanium disulfide (TiS2) 2D crystals. A two-step atomic layer deposition (ALD) – chemical vapor deposition (CVD) approach is proposed and being developed to synthesize TiS2 2D nano-samples. As a first step, a monolayer of TiO2 is grown by ALD. Sulfurization conversion of the as-grown TiO2 into TiS2 is to be next carried out in a house-built horizontally-oriented, hot-wall CVD reactor purged with Argon gas at 750 C for ~ 10-30 mins. Compared to other high-temperature thermal annealing, wet chemical and mechanical exfoliation techniques, the ALD-CVD method is capable of producing reproducibly a single monolayer TiS2 2D films of high purity and crystalline order. The crystal structure, morphology and electronic properties of the TiS2 crystals will be subject to further investigations and analysis done by carrying out TEM, SEM, EDX, AFM, RAMAN and PL as well as low noise I-V measurements