Potential fluctuations in heterostructure devices

Abstract

The random positions of ionized-impurity ions in doped heterostructures give rise to a random potential, which we have analyzed using a self-consistent method that includes nonlinear screening. A two-dimensional electron gas becomes highly inhomogeneous as its average density is lowered, eventually breaking into isolated puddles and undergoing a classical metal-insulator transition. A quantum wire formed by split gates is strongly distorted by the random potential, impeding ballistic propagation. The wire becomes discontinuous before it is narrow enough to support monomode propagation.