Modeling parallel conduction in GaAs/AlxGa1−xAs heterostructures

Abstract
We consider several features of the dc properties of illuminated, n‐type GaAs/AlxGa1−x As heterostructures that normally are neglected when modeling the parallel conduction. These are: (1) multivalley conduction in the undepleted AlxGa1−x As layer, (2) internal resistances in the heterostructure, (3) illumination‐dependent properties of the undepleted layer or of the internal resistances, and (4) the photoexcitation from the shallow donor component of the DX center. We show the importance of these refinements by comparing the calculated carrier densities with those from experimental results obtained in the range 4.2–320 K. The comparison shows that (1)–(3) are important effects that should be considered when modeling the dc conduction, but (4) can safely be neglected in the samples we have studied.