Charging of a Single InAs QD with Electrically-Injected Holes using a Lateral Electric Field.

Electric field tuning of single InAs quantum dots (QDs) provides an important tool for physics experiments and for the development of scalable and in situ-tunable devices. Control of a single QD with either a growth direction or an in-plane electric field is well established, but a device that can apply the twodimensional (2D) vector electric fields necessary to simultaneously and independently tune more than one parameter has not yet been demonstrated. We use COMSOL MULTIPHYSICS simulations to illustrate the device-design challenges in applying a uniform 2D electric field in a GaAs solid-state system and to systematically explore the effects of electrode coverage, mesa size, and doping on the device performance. We develop and present a design that can apply 2D electric fields to a single QD while remaining compatible with optical experiments. We then fabricate and characterize a proof-of-concept device that validates the design presented here. We discuss the applications for this device and the potential for full 2D-electric-field control of a single QD or a quantum-dot molecule.