Electric-field-induced charge noise in doped silicon: Ionization of phosphorus donors

We report low-frequency charge noise measurement on silicon substrates with different phosphorus doping densities. The measurements are performed with aluminum single electron transistors (SETs) at millikelvin temperatures where the substrates are in the insulating regime. By measuring the SET Coulomb oscillations, we find a gate-voltage-dependent charge noise on the more heavily doped substrate. This charge noise is attributed to the electric-field-induced tunneling of electrons from their phosphorus donor potentials. (c) 2006 American Institute of Physics.