Abstract
Transmission electron microscopy (TEM) techniques are applied to characterize the interfaces of epitaxial III-V semiconductor heterostructures with high spatial resolution and to analyze compositional variations at interfaces. As expected, realistic interfaces of compound semiconductors are not chemically sharp but there is a transition region at the interface. The functional dependence of the smooth change in composition is sigmoidal and can be described using an analytical expression, thus enabling a quantitative characterization of the interface width. The model gives a very good description of the distribution profiles and applies to several material systems, including the interfaces of As-based alloys and those of the non-common-atom InAs/GaSb short-period superlattices. The analysis of (Ga,In)(N,As)/GaAs quantum wells reveals that there is a connection between the interface properties in this material system and the miscibility gap of the alloy. (C) 2008 Elsevier B.V. All rights reserved.