Papers by Keyword: Electronic States

Abstract: In this work, we study theoretically and analytically the electronic transport through a nanowire structure composed of a finite cylindrical quantum wire (CQWR) based on barrier AlGaAs semiconductor, sandwiched between two semi-infinite cylindrical GaAs quantum well wires (CQWWRs). Using the Green function approach to determine the electronic structure of this artificial nanostructure, which is analyzed as a function of the geometrical and physical parameters of nanowires structure. The results show the eigen states (confined states), when they interact with the incoming electronic waves from the first semi-infinite cylindrical GaAs quantum well wire. The decrease of the radius of the system leads to the energy quantization of the electrons and the electronic states move towards high energies until a critical radius R_c=20Å below which no electronic state can exist. In addition, we found that the electronic energy levels of the finite cylindrical quantum wire depend on the mole fraction of aluminum and the ratio between the radius of the cylindrical nanowires and the thickness of the barrier, which are the most important parameters in the optimization of the cylindrical quantum wires nanostructure.Keywords: Cylindrical Quantum Wire, Nanowire, Electronic States, Green Function

Abstract: Since introducing Rapid Thermal Annealing, there has been disagreement among experimental data of ion-implanted and annealed layers. One explanation of these differences is the impact of optical irradiation and its interaction with semiconductor material. Although no plausible explanation has been offered, experimental evidence of “photonic effects” was reported in many works. In this work we estimate energy per atom available during recombination of the excited carriers. It is argued that the localization of energy states inside the band gap in ion-implant damaged material is responsible for “photonic effects.”

Abstract: The effect of molybdenum substitution in electronic structures of manganese dioxide has been calculated by the DV-Xα molecular orbital method. The molybdenum atom substituted for manganese atom located in center-sited of (Mn15O56)-52 cluster model. By the molybdenum substitution the energy band gap between the highest occupied molecular orbital (HOMO) of valence band and the lowest unoccupied molecular orbital (LUMO) was decreased, also the interaction of Mn-3d and O-2p was weakened but that of Mo-4d and O-2p was intensified. Both bonds of (Mn15O56)-52 and (Mn14MoO56)-52 was composed of not only ionic but also partially covalent.

Abstract: The elastic deformation and piezoelectric field in GaN /AlN/ quantum dots have been investigated. The electronic levels of quantum dots have been given in this paper. The 3D strain field and piezoelectric potential are calculated based on and the effective mass theory and finite element method. The effect of spontaneous and piezoelectric polarization is taken into account in the calculation. The ground bound state and the several lowest excited states of quantum dots have been studied. It is found that the size of quantum dots controls the conduction band edge, electronic levels and more other optical properties. The calculation results are very helpful in designing high quality infrared photodetector and laser.