Homoepitaxial growth of large-area rhombohedral-stacked MoS₂

Interlayer stacking is an important degree of freedom to tune the properties of two-dimensional materials and offers enormous opportunities for designing functional devices. As a classic example, rhombohedral-stacked (3R) two-dimensional materials exhibit ferroelectricity and optical nonlinearity that are non-existent in naturally abundant hexagonal-stacked (2H) counterparts. However, the ability to grow stacking-controlled large-area films remains challenging due to the thermodynamic competition of different polytypes. Here we report the chemical vapour deposition growth of two-inch wafer-scale 3R-MoS₂ films with high phase purity by homoepitaxy on top of a crystalline monolayer MoS₂. A defect-promoted nucleation mechanism was proposed, in which Mo-substituted sulfur vacancy is identified as one of the possible defects promoting 3R stacking. We fabricate ferroelectric semiconductor field-effect transistors with 3R-MoS₂ channels and demonstrate non-volatile memory characteristics. The control of interlayer stacking is an essential step towards the large-scale production of two-dimensional materials for multifunctional integration.