Quantum Computer Development with Single Ion Implantation

Spins of single donor atoms are attractive candidates for large scale quantum information processing in silicon. Formation of devices with a few qubits is crucial for validation of basic ideas and development of a scalable architecture. We describe our development of a single ion implantation technique for placement of single atoms into device structures. Collimated highly charged ion beams are aligned with a scanning probe microscope. Enhanced secondary electron emission due to high ion charge states (e. g., P-31(13+), or Te-126(33+)) allows efficient detection of single ion impacts. Studies of electrical activation of low dose, low energy implants of P-31 in silicon show a drastic effect of dopant segregation to the SiO2/Si interface, while Si3N4/Si retards P-31 segregation. We discuss resolution limiting factors in ion placement, and process challenges for integration of single atom arrays with control gates and single electron transistors.