Effects of geometry on electronstates in semiconductor quantumpoint contacts

Abstract: Recent preliminary experiments appear to show that using the electron-electron interaction as a way to filter electrons through a quantum point contact (QPC) according to spin might be possible. The same experiments also show that the geometry of the constriction has an effect on the filtering. If true this might be an important element for realizing spintronic devices. This project models and simulates a QPC made by using electrostatics on a layered AlGaAs/GaAs heterostructure, where different geometries of the split gates are tested. The modeling is done by using the Hartree-Fock equations with Dirac interaction as an idealized screened Coulomb potential. It is found that in the case where the conduction region is two semi-infinite wires, it is possible to completely spin-polarize the electrons in the constriction that forms the QPC. This project shows little difference in spin-polarization for tested split gate geometries.