Role of Precursors Chemistry on the Growth and Band Alignment of Few-Layers MoS2 From Liquid Chemical Vapor Deposition

Molybdenum disulfide (MoS2) is one of the extensively studied 2D materials due to its diverse physical, electrical, and chemical characteristics. However, achieving controlled synthesis and reproducibility of MoS2 nanosheets on a large scale continues to be challenging. Chemical vapor deposition (CVD) is recognized as a highly viable method for growth, given its flexibility, excellent reproducibility, and capability for large-scale production. Here, we report on the growth of few-layers of MoS2 via liquid-precursor CVD using different inorganic promoters. Firstly, we study the optimal volume of the solution to achieve as thin as 2 layer thick MoS2 uniformly grown at a cm2 scale using ammonium heptamolybdate (AHM) with inorganic seed precursors, namely NaOH, KCl, and KI. Focusing on growth, we studied the growth uniformity of the as-grown MoS2. Later, we inferred the band alignment analysis of three layers of MoS2 against a SiO2 / Si substrate using internal photoemission spectroscopy (IPE). We found a change in the valence band position from IPE threshold value of 3.9-4.2 eV depending on the type of inorganic promoter used with respect to the expected value of 3.6eV from bare MoS2, thus suggesting a role of the precursor chemistry on the properties of the sogrown few-layers of MoS2