Self-excitation in nanoelectromechanical charge shuttles below the field emission regime

The behaviour of a nanomechanical electron shuttle for applied dc-bias is investigated below the field emission regime. Simulations of the distribution of the electrical potential between the shuttling island and the leads show that field emission, which has recently been observed in a driven electron shuttle, can also play a role in the self-oscillating shuttle. For realistic experimental parameters of a silicon-based shuttle below the field emission regime, it is shown numerically that only one Coulomb step might be observable