Origin of carrier localization on two-dimensional GaN substitution layers embedded in GaAs

The electronic properties of GaAs containing a two-dimensional GaN substitution layer are studied by means of the empirical pseudopotential method in a periodic modeling approach. These are found to be anomalous compared with A(III)-B(V) semiconductors containing other two-dimensional substitution layers, i.e., not only one but two states in the lower conduction-band region of the GaAs host material are perturbed. It is shown that this anomaly originates from chemical and size effects associated with the embedded GaN substitution layer. The theoretical results can be correlated with first experimental investigations on the GaN/GaAs system.