Controlled single electron transfer between Si:P dots
  We demonstrate electrical control of Si:P double dots in which the potential is defined by nanoscale phosphorus doped regions. Each dot contains approximately 600 phosphorus atoms and has a diameter close to 30 nm. On application of a differential bias across the dots, electron transfer is observed, using single electron transistors in both dc- and rf-mode as charge detectors. With the possibility to scale the dots down to few and even single atoms these results open the way to a new class of precision-doped quantum dots in silicon. 
T. M. Buehler, V. Chan, A. J. Ferguson, A. S. Dzurak, F. E. Hudson, D.   J. Reilly, A. R. Hamilton, R. G. Clark, D. N. Jamie...