Gate-controlled charge transfer in Si:P double quantum dots

We present low temperature charge sensing measurements of nanoscale phosphorus-implanted double dots in silicon. The implanted phosphorus forms two 50 nm diameter islands with source and drain leads, which are separated from each other by undoped silicon tunnel barriers. Occupancy of the dots is controlled by surface gates and monitored using an aluminium single-electron transistor which is capacitively coupled to the dots. We observe a charge stability diagram consistent with the designed many-electron double-dot system and this agrees well with capacitance modelling of the structure. We discuss the significance of these results to the realization of smaller devices which may be used as charge or spin qubits.