Browsing by Department "Leipzig University"

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Effects of alloy composition and Si-doping on vacancy defect formation in (InxGa1- x)2O3 thin films
(2018-03-28) Prozheeva, V.; Hölldobler, R.; Von Wenckstern, H.; Grundmann, M.; Tuomisto, F.
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Various nominally undoped and Si-doped (InxGa1- x)2O3 thin films were grown by pulsed laser deposition in a continuous composition spread mode on c-plane α-sapphire and (100)-oriented MgO substrates. Positron annihilation spectroscopy in the Doppler broadening mode was used as the primary characterisation technique in order to investigate the effect of alloy composition and dopant atoms on the formation of vacancy-type defects. In the undoped samples, we observe a Ga2O3-like trend for low indium concentrations changing to In2O3-like behaviour along with the increase in the indium fraction. Increasing indium concentration is found to suppress defect formation in the undoped samples at [In] > 70 at. %. Si doping leads to positron saturation trapping in VIn-like defects, suggesting a vacancy concentration of at least mid-1018 cm-3 independent of the indium content.
Expanding the hydride chemistry: antiperovskites A3MO4H (A = Rb, Cs; M = Mo, W) introducing the transition oxometalate hydrides
(2022-05-25) Mutschke, Alexander; Schulz, Annika; Bertmer, Marko; Ritter, Clemens; Karttunen, Antti J.; Kieslich, Gregor; Kunkel, Nathalie
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
The four compounds A3MO4H (A = Rb, Cs; M = Mo, W) are introduced as the first members of the new material class of the transition oxometalate hydrides. The compounds are accessible via a thermal synthesis route with carefully controlled conditions. Their crystal structures were solved by neutron diffraction of the deuterated analogues. Rb3MoO4D, Cs3MoO4D and Cs3WO4D crystallize in the antiperovskite-like K3SO4F-structure type, while Rb3WO4D adopts a different orthorhombic structure. 2H MAS NMR, Raman spectroscopy and elemental analysis prove the abundance of hydride ions next to oxometalate ions and experimental findings are supported by quantum chemical calculations. The tetragonal phases are direct and wide band gap semiconductors arising from hydride states, whereas Rb3WO4H shows a unique, peculiar valence band structure dominated by hydride states.