Study On Exciton Binding Energy Of Cd _1-x Mn Te / CdTe Quantum Wells

With the development of the quantum well material, the quantum well devices are widely used in various fields. Exciton is of great significance to describe the optical and electrical properties of the semiconductor, and the exciton effect in semiconductor optical absorption、luminescence and the nonlinear optical effect and other physical processes has important influence, so the research on exciton has a great application prospect to design and development in semiconductor optoelectronic devices. Compared with the semiconductor material, in the quantum well structure, the exciton binding energy is much larger, and more stable at higher temperature or under the effect of electric field. Theoretically study the electronic states of a quantum well material for new quantum well devices design has important theoretical value and guiding significance.Cd Mn Te quantum well material is a kind of new type of semiconductor material, Unlike other semiconductor materials, it has the special properties of the magnetic and conductivity, Which is the electrical and optical properties of quantum well and superlattice and the magnetic effect of semimagnetic semiconductor. So it has a potential value in applications, and further research on Cd Mn Te material has important significance.In this thesis, the exercition binding energies in Cd1-x Mnx Te/Cd Te quantum well materials are calculated using variational method under the effective-mass envelope-function approximation, the main contents of this paper are presented as follows:1. Quantum well material and Cd1-x Mnx Te/Cd Te quantum well materials’ development and application are introduced and the principle of quantum wells is also described.2. The calculation method of the main theory of electronic states in quantum well structures is introduced briefly, namely the effective mass envelope function, shooting method, variational method and the exciton binding energy calculation methods, focuses on the method of calculating the exciton binding energy.3. In the effective mass approximation, using the variational method of exciton in Cd1-x Mnx Te/Cd Te quantum well in the binding energy of a detailed calculation and research. In single quantum well, quantum well and quantum wells as the theoretical model, with no electric field in quantum well exciton binding energy, the Bohr radius and non correlation probability calculation, Mn components and external electric field on the binding energy was calculated and the influence of. The results show that the exciton binding energy increases first and then decreases along with the change of the well width, the maximum value appeared, Bohr radius changes with the variation of the well width and the binding energy of the contrary, showed a trend of first increase and then decrease, at the same time, analysis of material composition effects on the binding energy of the electron and hole separation, simple introduction non probability, finally discusses the effect of electric field on the exciton binding energy4. The exciton binding energy in symmetric quantum well is discussed, and the parabolic quantum well and triangular quantum well as a theoretical model in the effective mass approximation, using the variational method of exciton in a Cd1-x Mnx Te/Cd Te parabolic and triangular quantum wells with the calculation and research. The results show that the binding energy increases with the well width change trend with the same type of quantum well exciton in parabolic type and triangular quantum well, at the same time square, parabolic and triangle is different.5. Asymmetric quantum well is studied in the exciton binding energy, with step quantum well and asymmetric quantum well as theoretical model. Simple to calculate the exciton binding energy, Bohr radius and the associated probability, discussed the Mn component of an electric field and the effect on the binding energy. Calculation data of some semiconductor photoelectric device design and production to provide some theoretical and experimental basis.