Quantum-confined Stark shift for differently shaped quantum wells

Abstract

The quantum-confined Stark shift was calculated, using a numerical method, for eight differently shaped simple Al0.4Ga0.6As/AlxGa1-xAs quantum wells. The dependence of the electron and heavy-hole ground-state interband transition energy on external electric field, quantum well profile and its thickness was investigated. Calculations also include the excitation binding energy, the overlap of the electron and hole wavefunctions and their average spatial separation. A wider well has a larger Stark shift, independent of its shape. An extensive comparison was made of the field response to differently shaped wells having the same zero-field electron ground-state energy (78 meV). The thinnest was a 51 AA wide square well and the thickest a 261 AA asymmetric triangular well. The symmetric and asymmetric triangular wells were found to exhibit the largest Stark shifts but also had a larger reduction of the overlap and exciton binding energy. The square well, on the contrary, had the smallest Stark shift but also smaller variation of the overlap and exciton binding energy. Other wells exhibited characteristics between these two extreme cases.