Stark shift effects in rectangular and graded gap quantum wells

We study the Stark effect in rectangular quantum wells and in quantum wells with linear variation of the composition. The energies of the bound electr onic states, the transition energies and their Stark shifts are calculated when a longitudinal electric field is applied. The spatial overlap of the e lectron and hole states and the intensity of the main optical transitions a re considered, and their dependence on the electric field strength is discu ssed. We compare the Stark effect characteristics of the rectangular and gr aded composition quantum wells. Numerical calculations are performed within the framework of a semi-empirical sp(3)s* tight-binding model, the virtual crystal approximation and the surface Green function matching method, A co mparison between the theoretical results and the experimental data availabl e for these systems is made, and a critical discussion is presented. (C) 19 99 Elsevier Science B.V. All rights reserved.