Mesoscopic Effect Of Quantum Dots Systems

With the miniaturizing of semiconductor device, mesoscopic physics has been developed and paid great interest. In these low dimensional mesoscopic systems that allow the energy band to be tailored, quantum size effect and quantum interference properties of electron liquids give rise to many novel and marvelous phenomena and thus 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, we present in some detail theoretical investigation, using Green's function approach, on the spectral and quantum-transport properties of several quantum dots systems.The thesis consists of six chapters. Chapter one is an introduction, which reviews some important experimental and theoretical developments of mesoscopic physics. Chapter two gives a detailed description of Green's function theory used in the follow chapters.In chapter three, we study the spectral properties and electronic transport properties of asymmetrical double-dot molecule using causal Green's function approach. The system is modeled by an Anderson-type Harmiltonian. The Green's functions are derived by a equation-of-motion technique. The numerical results show that there exist remainder of conductance at antiresonance state. In addtion, the indirect tunneling plays an important role in conductance of asymmetrical double-dot molecule.In chapter four, based on the Keldysh nonequilibrium Green's function technique, we study electronic transport through one-dimensional multiple quantum dots arrays. The on-site Coulombinteraction is ignored. A general formula for the current through a one-dimensional multiple quantum dots array is derived. The dependense of resonant transmission on the structure parameters of the quantum dot arrays is also given.In chapter five we propose quantum-dots ring model. Based on the Keldysh nonequilibrium Green function(NGF) technique, we study electronic transport through a quantum dots ring. A transport spectral of quantum dots ring is given. We find that the differential conductance oscillates with the magnetic flux through the quantum dots ring.The last chapter presents a conclusion of this thesis and some prospects for this investigation.