Scanning tunnelling microscope fabrication of arrays of phosphorus atom qubitsfor a silicon quantum computer

Abstract

Recognition of the potentially massive computational power of a quantumcomputer has driven a considerable experimental effort to build such a device. Ofthe various possible physical implementations, silicon-based architectures areattractive for the long spin relaxation times involved, their scalability, and ease ofintegration with existing silicon technology. However, their fabrication requiresconstruction at the atomic scale—an immense technological challenge. Here weoutline a detailed strategy for the construction of a phosphorus in siliconquantum computer and demonstrate the first significant step towards thisgoal—the fabrication of atomically precise arrays of single phosphorusbearing molecules on a silicon surface. After using a monolayer hydrogenresist to passivate a silicon surface we apply pulsed voltages to a scanningtunnelling microscope tip to selectively desorb individual hydrogen atoms withatomic resolution. Exposure of this surface to the phosphorus precursorphosphine results in precise placement of single phosphorus atoms on thesurface. We also describe preliminary studies into a process to incorporatethese surface phosphorus atoms into the silicon crystal at the array sites.