Delta-doping And Manipulation Of Electron-spin Filtering Effect In Magnetically And Electrically Confined Semiconductor Heterostructures

Semiconductor spintronics is a emerging interdisciplinary subject.Its main objective is to manipulate the spin to represent digital information,and by using the spin-related properties of electrons to design and fabricate a new type of semiconductor device — spin-electronic device.How to cause spin polarization of electrons in semiconductor materials and regulate the polarization are the important direction in the field of semiconductor spintronics.Up to now,some effective methods have been proposed,one of which is to use magnetic semiconductor heterostructures to realize electron spin polarization and it's manipulation in semiconductor materials.In this thesis,we study a class of magnetic semiconductor heterostructures — magnetically and electrically confined semiconductor heterostructures(including parallel and embedded structures),and investigate the manipulation of electron spin filtering effect by Delta-doping with the help of the combining theoretical analysis with numerical calculation.The full text is divided into five chapters.In the first chapter,we introduce the research field of semiconductor spintronics,the research direction of electron spin polarization and manipulation in semiconductor materials,the research trends of magnetic semiconductor heterostructures and spin filtering effect,and the research content of this thesis.The research methods adopted in this thesis is in Chapter 2,including improved transfer matrix method and Landaur-Burttiker conductivity theory.In chapter 3,we study the effect of Delta-doping on electron spin filtering in the magnetically and electrically confined semiconductor heterostructure with parallel configuration.In chapter 4,we study the magnetically and electrically confined semiconductor heterostructure with embedded configuration,and discuss the manipulation of Delta-doping on electron spin filtering effect.Finally,the fifth chapter is the summary and prospect,points out the innovation of this thesis,concludes the important conclusions,and looks forward to the future research direction.The results obtained in this thesis mainly include three aspects:(1)After the introduction of Delta-doping,significant electron spin filtering effect still appear in the magnetically and electrically confined semiconductor heterostructures under consideration.In the magnetically and electrically confined semiconductor heterostructures,the electrical confinement breaks the inherent magnetic field symmetry in magnetic confinement,resulting in the generation of electron spin polarization.The Delta-doping does not change the breaking symmetry in the structure,and does not affect the Zeeman coupling between electron spin and magnetic field.(2)However,the Delta-doping has a significant impact on the electron spin filtering effect in the magnetically and electrically confined semiconductor heterostructures.That is,the size and polarity of the electron spin filtering effect can be controlled by changing the weight or position of the Delta-doping,because the effective potential perceived by electrons in the structures is closely related to this Delta-doping.(3)Therefore,the magnetically and electrically confined semiconductor heterostructures can be used as Delta-doped adjustable or structurally controllable electronic spin filters,and whose spin polarization can be controlled by the Delta-doping.The results of this study can not only provide an effective way to realize the manipulation of electron spin polarization in semiconductor materials,but also provide a controllable electronic spin filter device,which can be used as an adjustable spin polarization source for semiconductor spintronics devices.