Single atom lithography and its applications

A novel technique for single atom lithography has been developed for the fabrication of nanostructures. It is based on a focused ion-beam with a retarding field stage, which enables the ion impact energy to be reduced to any level down to 0 eV. An ion detector has been designed and incorporated in the system which has a quantum detector efficiency close to 100% for high energy ion impacts and is capable of detecting the arrival of single Au+ ions with energies as low as 30 eV. The system has been used to deposit nanostructures in the size range 1-5 nm in diameter. The relation of size to surface morphology and to beam parameters has been studied. A new system operating in UHV conditions has been commissioned to enhance the study, particularly with respect to nucleation of particles and surface mobility effects. Initial experiments on a Coulomb blockade device with islands fabricated with the system have been conducted.