Ion implanted Si:P double-dot with gate tuneable interdot coupling
  We report on millikelvin charge sensing measurements of a silicon double-dot system fabricated by phosphorus ion implantation. An aluminum single-electron transistor (SET) is capacitively coupled to each of the implanted dots enabling the charging behavior of the double-dot system to be studied independently of current transport. Using an electrostatic gate, the interdot coupling can be tuned from weak to strong coupling. In the weak interdot coupling regime, the system exhibits well-defined double-dot charging behavior. By contrast, in the strong interdot coupling regime, the system behaves as a single-dot. 
V.C. Chan, T.M. Buehler, A.J. Ferguson, D.R. McCamey, D.J. Reilly,   A.S. Dzurak, R.G. Clark, C. Yang, D.N. Jamieson