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 degrees 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.