Ammonium Hydroxide-Assisted Growth of Large-Scale Single-Crystalline Molybdenum Disulfide

Controllable, massive synthesis of low-dimensional materials is one of the important cornerstones for the development of new functional devices oriented to high-tech industries, and the key to realize the broad application prospects in the quantum realm. How to synthesize high-quality low-dimensional materials for the next-generation high-performance devices has been regarded as a significant research direction in the field of functional material preparation technology. Here, we developed a convenient method via a solution-assisted thin-film precursor to replace the conventional solid-state powder precursor by taking advantage of the soluble nature of molybdenum trioxide in ammonium hydroxide, which can remarkably reduce the supersaturation state of vapor reactants and thus reduce the nucleation density, beneficial for the growth of large-scale single-crystalline molybdenum disulfide monolayers. The effect of the precursor concentration on the growth process has been systematically investigated. High-resolution transmission electron microscopy and temperature-dependent optical characterizations have been performed to examine the crystal quality of the ammonium hydroxide-assisted synthesized samples.