SinBeRISE CREATE, National Research Foundation , CREATE Tower, 1 Create Way, Singapore 138602, Singapore.
Department of Chemistry, National University of Singapore , 3 Science Drive 3, Singapore 117543, Singapore.
J Am Chem Soc. 2017 Jul 12;139(27):9392-9400. doi: 10.1021/jacs.7b05131. Epub 2017 Jul 3.
Atomically thin molybdenum disulfide (MoS), a direct-band-gap semiconductor, is promising for applications in electronics and optoelectronics, but the scalable synthesis of highly crystalline film remains challenging. Here we report the successful epitaxial growth of a continuous, uniform, highly crystalline monolayer MoS film on hexagonal boron nitride (h-BN) by molecular beam epitaxy. Atomic force microscopy and electron microscopy studies reveal that MoS grown on h-BN primarily consists of two types of nucleation grains (0° aligned and 60° antialigned domains). By adopting a high growth temperature and ultralow precursor flux, the formation of 60° antialigned grains is largely suppressed. The resulting perfectly aligned grains merge seamlessly into a highly crystalline film. Large-scale monolayer MoS film can be grown on a 2 in. h-BN/sapphire wafer, for which surface morphology and Raman mapping confirm good spatial uniformity. Our study represents a significant step in the scalable synthesis of highly crystalline MoS films on atomically flat surfaces and paves the way to large-scale applications.
原子级薄的二硫化钼（MoS）是一种直接带隙半导体，有望在电子学和光电子学中得到应用，但可扩展合成高结晶性薄膜仍然具有挑战性。在这里，我们通过分子束外延法成功地在六方氮化硼（h-BN）上外延生长了连续、均匀、高结晶性的单层 MoS 薄膜。原子力显微镜和电子显微镜研究表明，在 h-BN 上生长的 MoS 主要由两种成核晶粒（0°对齐和 60°反对齐畴）组成。通过采用高生长温度和超低前体通量，可以大大抑制 60°反对齐晶粒的形成。由此产生的完全对齐的晶粒无缝融合成高结晶性薄膜。在 2 英寸的 h-BN/蓝宝石晶片上可以生长出大面积的单层 MoS 薄膜，其表面形貌和拉曼映射证实了良好的空间均匀性。我们的研究代表了在原子级平坦表面上可扩展合成高结晶性 MoS 薄膜的重要一步，为大规模应用铺平了道路。
