Electronic, transport, and excitonic properties of GeC/SiC van der Waals heterostructures: A first-principles investigation

While two-dimensional silicon carbide (SiC) shows promise for nanodevices, its optoelectronic applications are limited by its intrinsic indirect bandgap and strong electron–phonon scattering. To overcome these bottlenecks, the construction of GeC/SiC van der Waals heterostructures is proposed herein as an effective solution. Based on first-principles calculations and the GW-BSE (GW–Bethe–Salpeter equation) formalism, the underlying physical mechanisms by which this architecture resolves the aforementioned limitations are systematically elucidated. First, the isostructural coupling between GeC and SiC, combined with stacking engineering, is shown to induce a distinct type-II band alignment that facilitates spontaneous charge separation and robust electric-field tunability. Subsequently, addressing the transport limitations, acoustic deformation potential analysis indicates that the unique orbital hybridization delocalizes conduction band states, effectively reducing the electron effective mass, while simultaneously increasing the in-plane lattice stiffness by a factor of two. This synergistic interaction significantly suppresses intrinsic acoustic phonon scattering, resulting in an electron mobility nearly sevenfold higher than that of isolated SiC. Finally, mitigating the bandgap constraints, spatially indirect excitons are found to dynamically screen the Coulomb interaction, driving a redshift of the optical absorption edge from the ultraviolet to the near-infrared region. These findings illuminate the interfacial charge and transport dynamics and provide a theoretical foundation for designing high-performance two-dimensional optoelectronic devices.