Two-dimensional (2D) semiconductors, in particular transition metal dichalcogenides (TMDCs), have attracted great interest in extending Moore’s law beyond silicon^1,2,3. However, despite extensive efforts^{4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25}, the growth of wafer-scale TMDC single crystals on scalable and industry-compatible substrates has not been well demonstrated. Here we demonstrate the epitaxial growth of 2 inch (~50 mm) monolayer molybdenum disulfide (MoS₂) single crystals on a C-plane sapphire. We designed the miscut orientation towards the A axis (C/A) of sapphire, which is perpendicular to the standard substrates. Although the change of miscut orientation does not affect the epitaxial relationship, the resulting step edges break the degeneracy of nucleation energy for the antiparallel MoS₂ domains and lead to more than a 99% unidirectional alignment. A set of microscopies, spectroscopies and electrical measurements consistently showed that the MoS₂ is single crystalline and has an excellent wafer-scale uniformity. We fabricated field-effect transistors and obtained a mobility of 102.6 cm² V⁻¹ s⁻¹ and a saturation current of 450 μA μm^–1, which are among the highest for monolayer MoS₂. A statistical analysis of 160 field-effect transistors over a centimetre scale showed a >94% device yield and a 15% variation in mobility. We further demonstrated the single-crystalline MoSe₂ on C/A sapphire. Our method offers a general and scalable route to produce TMDC single crystals towards future electronics.

二维 (2D) 半导体，特别是过渡金属二硫属化物 (TMDC)，引起了人们对将摩尔定律扩展到硅之外的极大兴趣^1,2,3 。然而，尽管付出了广泛的努力^{4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25} ，在可扩展且工业兼容的基板上生长晶圆级 TMDC 单晶尚未得到很好的证明。在这里，我们演示了在 C 面蓝宝石上外延生长 2 英寸（~50 毫米）单层二硫化钼 (MoS ₂ ) 单晶。我们设计了蓝宝石 A 轴 (C/A) 的误切方向，该轴垂直于标准基板。尽管误切方向的变化不会影响外延关系，但由此产生的阶梯边缘打破了反平行MoS ₂域的成核能的简并性，并导致超过99%的单向排列。一组显微镜、光谱和电学测量一致表明MoS ₂是单晶并且具有优异的晶圆级均匀性。我们制作了场效应晶体管，并获得了102.6 cm ² V ^-1 s ^-1的迁移率和450 μA μm ^–1的饱和电流，这是单层MoS ₂中最高的。对厘米级 160 个场效应晶体管的统计分析显示，器件良率 >94%，迁移率变化 15%。我们进一步展示了 C/A 蓝宝石上的单晶 MoSe ₂ 。我们的方法提供了一种通用且可扩展的路线来生产面向未来电子产品的 TMDC 单晶。