Fabrication and characterization of few-hole quantum dots in undoped GaAs/AlGaAs heterostructures

We fabricated a single hole quantum dot on a AlGaAs/GaAs heterostructure with no intentional doping. The hole quantum dot shows varying charging energy and clear excited states, which suggests that it is in the last-few-hole regime. By changing the confinement of the barrier gates, the device can also be defined as a double quantum dot with tunable interdot coupling.