Single atom Si nanoelectronics using controlled single-ion implantation

We present recent developments in controlled single-ion implantation techniques. A low energy (14 keV) ion-beam is used to produce shallow phosphorus implants in high-purity Si. Single atom control during implantation is achieved by monitoring on-chip p-i-n detectors, integrated within the device structure, while positional accuracy of 20 nm is achieved via a nanolithographic, resist mask. This technique has been used to implant only two phosphorus dopant atoms for use as charge-based Si:P quantum bits (qubits). Voltages applied to precisely aligned surface electrodes control the double-donor system, and dual single-electron transistors (SETs) provide readout with spurious signal rejection. Preliminary low temperature measurements on devices implanted with less than 10 dopant atoms demonstrate isolated charge transfer events. (c) 2005 Elsevier B.V. All rights reserved.