An exchange-coupled donor molecule in silicon.

Gonzalez-Zalba, M F; Saraiva, André; Calderón, María J; Heiss, Dominik; Koiller, Belita; Ferguson, Andrew J · Nano Lett · 2014

basic_science · Level V

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Abstract

We present a combined experimental-theoretical demonstration of the energy spectrum and exchange coupling of an isolated donor pair in a silicon nanotransistor. The molecular hybridization of the atomic orbitals leads to an enhancement of the one- and two-electron binding energies and charging energy with respect to the single donor case, a desirable feature for quantum electronic devices. Our hydrogen molecule-like model based on a multivalley central-cell corrected effective mass theory incorporating a full configuration interaction treatment of the 2-electron spectrum matches the measured data for an arsenic diatomic molecule with interatomic distance R = 2.3 ± 0.5 nm.