dc.description.abstract | Various preparation methods have been proposed to produce high-quality molybdenum disulfide (MoS2) transistor channel layers, such as mechanical exfoliation, physical vapor deposition, chemical vapor deposition, molecular layer deposition, and metal-organic chemical vapor deposition. Among them, MoS2 thin films synthesized by chemical vapor deposition (CVD) exhibit better quality and electrical transport properties, making them widely used. Although the CVD method can produce large-area and high-quality MoS2 thin films, several factors can lead to poor film quality, such as atomic-scale defects, grain boundaries, and impurity doping, resulting in significant degradation of optical and electrical properties.
Compared to synthesizing MoS2 on crystalline sapphire substrates, direct synthesis on amorphous substrates(such as silicon oxide or silicon nitride) is advantageous for integrating into the back-end of line processes. However, there are still bottlenecks in achieving high-quality crystalline synthesis. In this study, by adjusting the parameters of the growth system, the variations and effects of various parameters were organized, leading to the achievement of large-area, high-crystallinity single-crystal MoS2 growth. The research results indicate that under the main conditions dominated by temperature, pressure, flow rate, etc., if within an appropriate range, MoS2 nanoparticles can be preliminarily grown. By combining precursor proportions and fine adjustments, single-crystal sizes can reach 10 µm or more. Raman analysis confirms the flake is single-layer, and photoluminescence analysis reveals a high crystalline quality of 58 meV.
Additionally, this study compared different substrate surface treatment methods to solve the nucleation and doping issues during growth. It was found that the use of the solvent acetone with an ultrasonic cleaning method can achieve high cleanliness and reduced the nucleation density from 10 sites/µm2 to 0.04 sites/µm2 after acetone clean treatment. The gold array test successfully addressed the limitations of nucleation disorder. By employing lower interfacial energy, MoS2 tended to nucleate heterogeneously around the array points, while suppressing homogeneous nucleation, achieving a selective nucleation effect. | en_US |