High-quality, ultrathin 2D-MoS2 layers with large area were grown on SiO2/Si substrates by using atmospheric pressure chemical vapor deposition (APCVD) at elevated temperatures. The growth precursors (MoO3 and S) were placed separately inside the double-zone furnace to control the growth parameters individually for better flexibility in the growth process. In this study, it was found that the shape and edge structure of the evolved MoS2 flakes were significantly influenced by the chemical potential of the Mo and S precursor concentration. In keeping with the concentration gradient of the Mo precursor (MoO3) on the substrate surface, the shape of MoS2 flakes changed from hexagonal to truncated triangle and then to triangular shapes, owing to the Mo-rich to S-rich conditions. The surface roughness and thickness of the differently shaped MoS2 flakes were studied by using atomic force microscope (AFM). Additionally, Raman and photoluminescence (PL) techniques were employed to characterize the crystalline quality, number of grown layers and optical performance of the as-grown MoS2 layers. Auger electron spectroscopy (AES) analysis and scanning electron microscopy (SEM) confirmed that the equilibrium crystal shape of the MoS2 was hexagonal under Mo-rich conditions. However, the shape of the MoS2 crystal changed to a triangle under S-rich conditions. Furthermore, the influence of chemical potential on the edge structure of the monolayer MoS2 and its effect on the equilibrium shape of the crystal were studied.

中文翻译：

---

化学势对化学气相沉积二维MoS2薄片形状演化的影响


通过在高温下使用常压化学气相沉积 (APCVD) 在 SiO2/Si 衬底上生长高质量、大面积的超薄 2D-MoS2 层。生长前驱体（MoO3 和 S）分别放置在双区炉内，以单独控制生长参数，从而提高生长过程的灵活性。在这项研究中，发现演化出的MoS2薄片的形状和边缘结构受到Mo和S前体浓度的化学势的显着影响。与基底表面上 Mo 前驱体 (MoO3) 的浓度梯度一致，由于富 Mo 到富 S 的条件，MoS2 薄片的形状从六边形变为截角三角形，然后变为三角形。利用原子力显微镜（AFM）研究了不同形状MoS2薄片的表面粗糙度和厚度。此外，还采用拉曼和光致发光 (PL) 技术来表征晶体质量、生长层数以及生长的 MoS2 层的光学性能。俄歇电子能谱（AES）分析和扫描电子显微镜（SEM）证实，在富Mo条件下，MoS2的平衡晶体形状为六方晶形。然而，在富硫条件下，MoS2晶体的形状变为三角形。此外，还研究了化学势对单层MoS2边缘结构的影响及其对晶体平衡形状的影响。