Optimization of growth parameters to obtain epitaxial large area growth of molybdenum disulfide using pulsed laser deposition

Abstract

2D transition metal dichalcogenides (TMDCs) are promising materials for device applications owing to their electronic, optical, and material properties varying with the number of monolayers. Synthesis of large area crystalline TMDC thin films is still challenging with techniques such as exfoliation and chemical vapor growth owing to the uncontrollability of deposition area and high temperature growths with toxic precursors, respectively. Pulsed laser deposition (PLD) is a technique that can overcome these challenges owing to stoichiometric layer by layer growth control by optimizing the growth parameters. In this study, we optimize parameters such as temperature, post-growth annealing, inert gas pressure, and substrate–target distance during PLD growth of MoS2 to obtain uniform and highly crystalline thin films on an ∼1 in.2 substrate. The optimized growth conditions are 800 °C with a 30 min post-growth annealing at a laser fluence of 2.2 J/cm2 with a substrate–target distance of 5 cm and 0.5 mTorr of argon partial pressure. An RMS roughness of 0.17 nm was obtained for 3 nm (4 monolayers) thick MoS2 films with a thin film conductivity of ∼4000 S/m.