Reliable single atom doping and discrete dopant effects on transistor performance

For reliable deterministic single-atom doping, i.e. single-ion implantation (SII), improvement of single-ion detection efficiency is successfully achieved by controlling channel potential using back-gate of transistor. We also fabricate transistors whose channel dopants are introduced one-by-one using SII and find that subthreshold current becomes larger when dopants are located at drain-side than source-side. The single-atom doping method could contribute to the novel device development beneficial for extensibility of doped-channel device technologies towards atomic-scale devices and single-dopant device.