The atomic scale structure and the electronic properties of a graded composition semiconductor layer

Abstract
We report the results of a study on the relationship between the structural and electronic properties of a graded layer of undoped AlxGa1−xAs, where x was specified to increase linearly from 0 to 0.2 over 50 nm. The layer was grown by molecular-beam epitaxy between layers of doped GaAs. A high-resolution dark-field transmission electron microscopy imaging technique of combining information from 002 and 002̄ reflections of AlxGa1−xAs allowed us to image the graded region with near atomic resolution. Differences between the predicted and measured diode performance of the graded layer are discussed in the light of our results.