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Published online by Cambridge University Press: 01 February 2011
We investigated the roughness of the electronic interfaces of GaAs p-n multilayers using cross-sectional scanning tunneling microscopy. We demonstrate that these interfaces exhibit a much larger roughness than the underlying essentially perfect ‘metallurgical’ interface, due to the individual long range electrostatic screening fields around each dopant atom near the interface and due to a clustering of dopant atoms. The clustering and the inherently connected local lack of dopant atoms gives rise to charge carrier depletion zones extending locally through entire nominally homogeneously doped layers once the layer thickness is close to the cluster dimensions. Thus, local variations in the dopant atom distribution limit the precision of the spatial and energetic positioning of the Fermi energy in nanoscale semiconductor structures.