Layer-controlled continuous MoS2 growth using a spin-coatable metal precursor buffer

Abstract

Continuous large-area MoS₂ growth holds significant potential for next-generation optoelectronic applications, yet achieving it efficiently and reproducibly with the conventional chemical vapor deposition (CVD) process remains a challenge due to inconsistent precursor adsorption and non-uniform nucleation. In this study, we developed a pH-optimized metal precursor buffer that enables uniform spin-coating and facilitates continuous MoS₂ growth. Sodium cholate (SC) acts as both a dispersant and a buffer, transforming molybdenum oxide into a dispersion-stable sodium molybdate (Na₂MoO₄)/SC complex. This complex forms a stable, uniformly spin-coatable dispersion at pH = 5.3, allowing it to form hydrogen bonds with the SiO₂/Si substrate. Additionally, increasing the complex concentration enhances precursor adsorption, enabling controlled MoS₂ layer formation via CVD. Using this approach, we successfully fabricated continuous, centimeter-scale MoS₂ films in varying layer numbers. Real-time observation reveals the growth kinetics of the continuous MoS₂ film in terms of contrast value, according to the reaction time and temperature, indicating that the growth can occur at temperatures as low as 500 °C. This stable, scalable, and reproducible spin-coating technique, utilizing a metal precursor buffer, offers a robust pathway for producing large-area transition metal chalcogenide structures, advancing the development of 2D material-based applications.