Wafer-scale growth of single-crystal graphene on vicinal Ge(001) substrate

Wafer-scale single-crystal graphene with high carrier mobility is essential as a promising channel material for the next-generation two-dimensional nanoelectronics. However, direct synthesis of wafer-scale single-crystal graphene on complementary metal oxide semiconductor (CMOS) compatible substrates still remains a challenge. Herein, we demonstrate that single-crystal graphene film with high mobility can be synthesized on the 15° miscut Ge(001) surface by perfectly aligning all the graphene islands and this feat has never been achieved on the normal Ge(001) surface. Both experimental observations and theoretical calculations suggest unidirectional alignment of the graphene islands on the 15° miscut Ge(001) surface is caused by suppression of graphene nucleation along the miscut direction of the vicinal surface. Ex situ atomic force microscopy (AFM) verifies that no additional graphene island nucleates after the initial nucleation process and wafer-scale single-crystal graphene is formed by the seamless stitching of the preferentially oriented graphene islands. The obtained wafer-scale single-crystal graphene possesses an ultrahigh carrier mobility, opening an avenue toward scalable fabrication of two-dimensional nanoelectronic devices based on single-crystal graphene without grain boundaries.