13 research outputs found
Electronic structure of -SiAlON: effect of varying Al/O concentration at finite temperatures relevant for thermal quenchin
-SiAlON is a prominent example of systems
suitable as hosts for creating materials for light-emitting diodes. In this
work, the electronic structure of a series of ordered and disordered
-SiAlON systems is investigated by means of
ab initio calculations, using the FLAPW and the Green function KKR methods.
Finite temperature effects are included within the alloy analogy model. We
found that the trends with the Al/O doping are similar for ordered and
disordered structures. The electronic band gap decreases with increasing by
about 1 eV when going from =0 to =2. The optical gap decreases
analogously as the electronic band gap. The changes in the density of states
(DOS) at Si and N atoms introduced by doping -SiN with Al
and O are comparable to the DOS at Al and O atoms themselves. The bottom of the
conduction band in -SiAlON is formed by
extended states residing on all atomic types. Increasing the temperature leads
to a shift of the bottom of the conduction band to lower energies. The amount
of this shift increases with increasing doping .Comment: 11 pages, 11 figures, 1 tabl
Multiple scattering theory for non-local and multichannel potentials
International audienceMethodological advances in multiple scattering theory (MST) in both wave and Green's function versions are reported for the calculation of electronic ground and excited state properties of condensed matter systems with an emphasis on core-level photoemission and absorption spectra. Full-potential MST is reviewed and extended to non-local potentials. Multichannel MST is reformulated in terms of the multichannel density matrix whereby strong electron correlation of atomic multiplet type can be accounted for in both ground and excited states