Unraveling the influence of substrate surface and temperature on microstructural evolution of crystalline MoS2 in atomic layer deposition

Abstract

In this study, we examine the atomic layer deposition (ALD) growth behavior of crystalline MoS₂ films on various substrates, including SiO₂, mica, and Al₂O₃, at deposition temperatures of ≥650 °C. The results show that the substrate surface energy and temperature significantly influence the MoS₂ growth dynamics, affecting the layer nucleation, surface morphology, and growth rate. High temperatures generally favor a stepwise growth pattern with a step size of one monolayer; however, the substrate surface energy distinctly affects the grain size and crystallinity. MoS₂ growth on mica, which has the lowest surface energy, results in larger, highly crystalline triangular grains and enables multilayer growth, whereas Al₂O₃, which has the highest surface energy, produces smaller, less crystalline grains. Temperature elevation further enhances the lateral grain expansion and crystallinity, especially on Al₂O₃ substrates with higher surface energies. By tailoring the substrate surface and deposition temperature, the key pathways for optimizing MoS₂ ALD growth are highlighted with the aim of enhancing the film uniformity and quality for nanoelectronic applications. This study provides critical insights into the ALD parameters that govern the growth of crystalline MoS₂ with implications for advancing scalable, high-performance 2D materials.