A tunable three-lead double quantum dot with a resorcinarene spacer

Configurations of multiple quantum dots in the two-dimensional electron gas of a GaAs-AlGaAs heterostructure are of considerable fundamental interest. In this paper, a fabrication process is presented which is scalable, forms robust structures, requires a minimum number of leads and enables access to the active device areas. A stable tunable double dot connected in series is formed by only three metallic gates, using methylcalix[4] resorcinarene as a dielectric spacer. A capacitance model for dot formation through screening by the spacer is presented, as well as low-temperature measurements showing the transition from a single to a double dot with varying interdot couplings. The method can easily be extended to the fabrication of multiple dots and more complex geometries.