Barrier Thickness On The Binding Energy Of Excitons In A GaAs/Al_xGa_1-xAs Three-Quantum-Well And Its Pressure Effect

A variational method is adopted to investigate the influence from the barrier thickness on the properties of excitons in GaAs/AlxGa1-xAs finite depth quantum wells using a three-quantum-well model.Firstly, some physical properties of quantum well structure models about multilayer materials were briefly reviewed in this thesis. The recent developments of variational laws about binding energies of impurity states and excitons in quantum wells with infinitely thick barriers and the influence of pressure on the related properties of materials and electrons are summarized and compared. The history and prospect of the development of superlattices and multiple quantum well materials are given. On this basis, the practical significance of the research in this thesis is put forward.Then, a calculation about the variation relations of the binding energy of excitons changing with the well width Lw and barrier thickness Lh is given and the influence from Al component is also discussed. The numerical results show that as the barrier thickness increasing the binding energy increases first and then trends to be stable for a wide width of wells; whereas the binding energy decreases primarily and then increases with the barriers thickness increasing for a less well width. There is a big difference between our results and that of the usual model of a finite well depth. The correction may provide a reference for the related theories and experiments. The results also indicate that the trend of the binding energy increasing linearly with pressure for the finite barrier thickness case is obviously less than that for the infinite barrier thickness case.