We measured a quantum dot formed by an impurity potential which shows quantized ballistic conductance plateaux with resonant tunnelling peaks replicated in the transition regions between plateaux at zero field. Interference between the incident and reflected electron streams produces structure in the current-voltage characteristics. 2.8 Regrowth of Structures on Patterned Epilayers MBE regrowth over ex situ optically patterned epilayers provides a promising technique for the growth of three-dimensional device structures. Standard thermal cleaning of patterned surfaces can be of limited effect resulting in poor quality regrowth interfaces and so a hydrogen radical cleaning chamber and surface decontamination process have been commissioned to achieve clean, smooth regrowth interfaces for ex situ patterned wafers. This allows the growth of high mobility 2DEGs and 2DHGs with a variety of imposed topologies close to the regrowth interface.
Lateral confinement is achieved by depletion of the gated region.
Work not covered in these sections was supported by other grants.