Numerical Simulation Of Quantum Dots’ Structures And Microwave Sintering Zno Powder

The dissertation "Numerical simulation of quantum dots’structures and microwave sintering ZnO powder", mainly achieving the numerical solving the electronic structures of quangtum dots by programming with the help of Matlab software. Based on comparing and analyzing the results obtained with other literatures, both the programs and models are reasonable and effective, then combining with the formulas derived which corresponding to the properties of quantum dots, some application examples are shown. These models above include pyramidal pure quantum dot, vertically aligned or/and horizontal coupling quantum dots, the introduced wetting layer, periodical quantum dots-in-a-well and so on. Some algorithms are improved and developed. In addition, the theme of microwave sintering is also studied in this paper, using the Comsol software, realizing the3D simulation of the process of microwave sintering the powder ZnO in furnace, taking the heating exchanging effect from the insulation layer and sintering atmosphere into account, we analyze and discuss the changes of electromagnetic and temperature field during the sintering period. The full text mainly consists of five parts, the corresponding research contents and conclusions are as follows:1, As the result of the conduction band non-parabolicity of the semiconductor, the conduction band electronic effective mass is related to the potential energy, discretizing the Schrodinger equation in the finite difference scheme, numerical computation using the common denominator, a fifth-order polynomial matrix is obtained. In order to solve the polynomial matrix, we propose a simple eigen energy scanning technology, based on the mathematics analysis and numerical computing, the effectiveness and practicality of the method is proven, and it can be extended to get the eigenvalues of the arbitrary polynomial matrix. Using this method, under the framework of band non-parabolicity, the isolated dot and the vertical aligned quantum dots system are studied, by changing the size of the quantum dot or/and the coupling distance in the quantum dots system and other conditions, access to a wealth of information on electronic states. 2, Using the finite difference method, the Schrodinger equation of the electronic conduction band is solved, and it is demonstrated effective for studying the true3D quantum dots-in-a-well structure, based on the finite difference methods having a wide range industrial application of simulation and its finite element format which can be automatically integrated the jump interface condition without the need to explicitly adding to, by changing the boundary conditions, we can calculate isolated and periodic arrayed quantum dots structure, respectively, due to the optical transition, the corresponding eigen-energy spectrum is discussed.3, Thanks to the mature technology of the growth of quantum dots, the current industrial and laboratory has been able to design and grow out of such as quantum dots embedded quantum wells, the coupled double quantum dots’structure and so on. Based on the pyramidal quantum dots and taking the wetting layer into account, we simulate and analyze the electronic information of the corresponding quantum dots’ system. A constant single-band electronic envelope function method is applied, its advantage lies not only can simulate arbitrary shape and structure of quantum dots, but also can obtain analysis results by a simple triangular integration, then at a moderate cost to guarantee the accuracy of the calculating results.4, The electronic envelope function plane wave expansion method is applied to solve the Schrodinger equation in the reciprocal space, simulating and comparing the electronic eigen spectrum from the quantum dots with different shapes (which embedded in quantum well under the periodic potential field, then the distribution of strain in the quantum structure is calculated diffusion. If assuming evenly distributing stress and uniform diffusion, by introducing Fick’s law in the Fourier space, in order to weaken the form factor integrated into the computations of simulating annealing post-processing which resulting in the interdiffusion, the electric field effect on electronic energy levels is studied in different electric field and the piezoelectric potential of the quantum dots is discussed, the local field effect formula is preliminarily derived, then analyzing the impact of different doping density and In concentration on the optical obsorption.5, We simulates the changes of temperature field (TF) in ZnO powder during the process of microwave sintering. According to the distribution of the electric field (EF) at the initial microwave heating, some parameters of the locations of ZnO powder and the ports of waveguides are fixed. By comparing with the single-source (SS) heating, the application of dual-source (DS) heating with the same power is demonstrated more effective. For the first time to simulate the process of DS microwave heating ZnO powder with the porous alumina insulation layer, and by the way of the comparative analysis of the heating characteristics of the powder’s center and boundary points with and without the insulation layer, the effect of the insulation is shown.