Experimental Observation of Sequential Electron Incorporation within P-Donor Molecules in a Silicon Nano-Transistor

Quantum dots formed by several P-donors can work as “molecules” and provide a robust single-electron tunneling operation. Here, we provide an experimental observation of clear and sustained quantum Coulomb blockade effect with one-by-one electron filling within multi-donor molecules formed in the channel of a silicon nano-transistor. Furthermore, the observed systematic decrease in charging energies with increasing electron occupation reflects the underlying molecular orbital physics, where higher-energy orbitals exhibit greater spatial extent. First-principles density functional theory simulations further confirm the molecular energy levels arising from the hybridization of individual donor states that facilitate single-electron transport.