Oxide Nanosheet Dielectrics for 2D Devices*

Two-dimensional materials provide a platform for small-scale and ultrathin electronics and the continued scaling of devices like field effect transistors (FETs). However, it is still necessary to develop high-k gate-dielectric materials that possess suitable band alignments and minimize electron leakage. 2D oxide nanosheets such as Ca₂Nb₃O₁₀ exhibit both high dielectric constants and good thermal stability, suggesting their potential for use in 2D-material-based FETs. In this work, we perform quantum mechanical calculations using density functional theory in order to model interface and defect properties of Ca₂Nb₃O₁₀. Calculations of interface band alignments of Ca₂Nb₃O₁₀ and various candidate 2D semiconductors allow for the determination of suitable material pairings for p- or n-type transistors. Atomic defects that arise during material fabrication and preparation, like oxygen vacancies, can create defect levels within the oxide band gap. Therefore, we calculated the position of these defect energy levels and how they align relative to the semiconductor band edges to provide insights into potential sources of electron leakage and device degradation in the proposed structures.