Dresden 2009 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
HL: Fachverband Halbleiterphysik
HL 48: Poster 2
HL 48.4: Poster
Donnerstag, 26. März 2009, 15:00–17:30, P2
Simulation of wurtzite-type nanostructures with an Effective Bond-Orbital model — •Stefan Barthel, Daniel Mourad, and Gerd Czycholl — ITP Universität Bremen
Empirical Tight-Binding models use a discrete set of atomic orbitals on each atomic position in order to calculate the electronic structure of a given material, while the hopping matrix elements are fitted in a self consistent way to empirical parameters. An Effective Bond-Orbital model (EBOM) uses the Tight-Binding approach, but considers the Bravais lattice instead of the atomic basis. This results in a less dimensional Hamiltonian, which reduces the computational time drastically e.g. for the simulation of nanostructures. In this work an EBOM for wurtzite type semiconductors is developed from scratch for nearest and second-nearest neighbour couplings in a basis set of sp3 orbitals. The LCAO-method or two-center-integral approximation has been extended to the needs of the wurtzite structure and is applied in order to relate all hopping parameters to a complete and known set of kp-parameters as well as critical point energies in the first BZ. Spin-orbit-coupling and crystal-field splitting is included too. Results for GaN and InN are in good agreement with existing Tight-Binding and ab-initio bandstructure calculations throughout the whole BZ and reproduce the accuracy of the kp-model around the zone-center exactly. This model is applied for the simulation of GaN/InN quantum dots by diagonalizing the Hamiltonian directly in the set of atomic orbitals. Nearest- and Second-Nearest-Neighbour results are compared to existing Tight-Binding calculations with focus on computational speed.