# Dresden 2020 – wissenschaftliches Programm

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# CPP: Fachverband Chemische Physik und Polymerphysik

## CPP 99: Frontiers in Electronic-Structure Theory - Focus on Electron-Phonon Interactions V (joint session O/CPP/DS/HL)

### CPP 99.9: Vortrag

### Donnerstag, 19. März 2020, 17:15–17:30, GER 38

**Electronic structure of β-SiAlON: effect of Al/O doping and of finite temperature** — •Saleem Ayaz Khan^{1}, Ondrej Šipr^{2}, Jiří Vackář^{2}, Robin Niklaus^{3}, Wolfgang Schnick^{3}, and Jan Minár^{1} — ^{1}University of West Bohemia, Plzen, Czech Republic — ^{2}Institute of Physics of the Czech Academy of Sciences, Prague, Czech Republic — ^{3}LMU Munich, Germany

Electronic structure of a series of ordered and disordered β-Si_{6-z}Al_{z}O_{z}N_{8-z} systems is investigated by means of ab initio calculations, using the FLAPW method as implemented in the wien2k code and Green function KKR method as implemented in the SPR-KKR code. 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 z by about 1 eV when going from z=0 to z=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 β-Si_{3}N_{4} with Al and O are comparable to the DOS at Al and O atoms themselves. The bottom of the conduction band in β-Si_{6-z}Al_{z}O_{z}N_{8-z} 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 z.