Tunable Tunnel Coupling in Vertically Stacked Symmetric FinFET-Based Ge Double Quantum Dots

We simulate a novel vertically stacked germanium double quantum dot (Ge-DQD) using a symmetric FinFET configuration. The tunnel coupling between the quantum dots is modulated by varying the thickness of the interlayer separating the top and bottom FinFET gates. The results reveal a trade-off between gate oxide and interlayer thickness. Thicker gate oxides reduce gate controllability, making the interlayer thickness the dominant parameter in tunnel coupling. Thicker interlayers suppress tunnel coupling and widen hybridized energy level spacing. These results offer alternative design strategies for precise control of inter-dot coupling.