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.