Molecular SETs with enhanced electrostatic control: A tri-gatedarchitecture using vanadium tris(dithiolene) as a quantum island

Abstract

Single-electron transistors (SETs) are promising candidates for low-power nanoelectronic applications due to their ability to control electron flow at the single-charge level. However, conventional SETs face challenges such as limited charge-state tunability, cross-talk, and reduced electrostatic precision as device dimensions scale down. To address these limitations, this study presents a theoretical investigation of a tri-gate single-electron transistor (TG-SET) that incorporates a redox-active vanadium tris(dithiolene) complex, V(edt)₃, as the molecular island. The TG-SET architecture introduces three independently controlled gate electrodes positioned around the molecular channel to enable spatially resolved electrostatic modulation. Using density functional theory (DFT) and non-equilibrium Green’s function (NEGF) calculations, the study models electronic structure and transport behavior under varying gate voltages and charge states. The results reveal stable Coulomb blockade plateaus, spin-resolved energy levels, and nonlinear current–voltage characteristics, demonstrating fine-tuned control over molecular charge and orbital alignment. A key outcome includes the extraction of gate–molecule coupling parameters through total energy fitting across multiple charge configurations. The TG-SET exhibits enhanced gate sensitivity, reduced leakage potential, and improved charge selectivity compared to conventional SETs. This work highlights the potential of tri-gated architectures in advancing molecular-scale electronics and provides a design framework for future experimental realization. The findings open new directions for the development of multifunctional, ultra-low-power devices in quantum computing, sensing, and molecular logic applications.