Epitaxial Integration of Transferable High-κ Dielectric and 2D Semiconductor

The synthesis of high-dielectric-constant (high-κ) dielectric materials and their integration with channel materials have been the key challenges in the state-of-the-art transistor architecture, as they can provide strong gate control and low operating voltage. For next-generation electronics, high-mobility two-dimensional (2D) layered semiconductors with dangling-bond-free surfaces and an atomic-thick thickness are being explored as channel materials to achieve shorter channel lengths and less interfacial scattering. Nowadays, the integration of high-κ dielectrics with high-mobility 2D semiconductors mainly relies on atomic layer deposition or transfer stacking, which may cause several undesirable problems, such as channel damage and interface traps. Here, we demonstrate the integration of high-mobility 2D semiconducting Bi₂O₂Se with transferable high-κ SrTiO₃ as a 2D field-effect transistor by direct epitaxial growth. Remarkably, such 2D heterostructures can be efficiently transferred from the water-soluble Sr₃Al₂O₆ sacrificial layer onto arbitrary substrates. The as-fabricated 2D Bi₂O₂Se/SrTiO₃ transistors exhibit an on/off ratio over 10⁴ and a subthreshold swing down to 90 mV/dec. Furthermore, the 2D Bi₂O₂Se/SrTiO₃ heterostructures can be easily transferred onto flexible polyethylene terephthalate (PET) substrates, and the as-fabricated transistors exhibit good potential in flexible electronics. Our study opens up a new avenue for the integration of high-κ dielectrics with high-mobility 2D semiconductors and paves the way for the exploration of multifunctional electronic devices.