Study Of Energy And Electronic Properties In Semiconductor Quantum Dots

With the miniaturizing of semiconductor device, mesoscopic physics has been developed and paid great interest. These low dimensional mesoscopic systems that allow energy band to be tailored, quantum size effect and so on give rise to many novel and marvelous phenomena and thus have received much current attention. As the typical representative exhibiting quantum effects, quantum dots systems have become one of the most active areas in mesoscopic physics in very recent year. In this thesis, electronic properties in semiconductor quantum dots (GaAs) are investigated in detail. The aim is to explore the physical mechanisms and the new effects in low-dimensional semiconductor systems, and to supply physical models and make the theoretical validity in designing novel quantum devices with better properties.In this thesis, using a parabolic potential as confinement potential in quantum dots and using a five point difference method to discrete the Schrodinger equations, an numerical self-consistent solution of 2D GaAs quantum dot is carried out based on density-functional theory (DFT). The ground state energy, the chemical potential, the binding energy and electron density have been computed in the limit of zero temperature. We also discuss the influence of impurities on the ground state energy and electron density. And have a comparison with the electron density of different confinement potential. In a word, it provides a reliable basis for experiment, is more conducive to the study of semiconductor materials.The thesis consists of five chapters. Chapter one is an introduction, which reviews the research progress of semiconductor quantum dots at home and abroad, the purpose and main content of the thesis. Chapter two gives a detailed description of quantum dot, including quantum properties, such as surface effect, the size effect, the Coulomb blockade effect and so on ,and application of quantum dots in all fields.In chapter three , we introduce the method of calculation used in the follow chapters, which involves three approximation, Hartree-Fock equation, density functional theory and procedures charts. In chapter four , the ground state energy, the chemical potential, the binding energy and electron density have been computed in the limit of zero temperature. We also discuss the influence of impurities on the ground state energy and electron density. And have a comparison with the electron density of different confinement potential. The ground state energy and the chemical potential increase with electron number, reduces with the size of quantum dots. For smaller quantum dots size, quantum effects are more remarkable. The binding energy of impurities, reduces with the size of quantum dots, increases with electron number .when impurity is further away from the center of dot, the binding energy is smaller.The last chapter presents a conclusion of this thesis and some prospects for this investigation.