Dresden 2017 – scientific programme
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DS: Fachverband Dünne Schichten
DS 36: Postersession I
DS 36.57: Poster
Wednesday, March 22, 2017, 17:00–19:00, P2-EG
angle-resolved photoemissions spectroscopy on MgGa2O4 — •Bonito Thielert1, Mattia Mulazzi1, Florian Titze1, Christoph Janowitz1, and Zbigniew Galazka2 — 1Humboldt-Universität zu Berlin, Inst. für Physik, Newtonstr. 15, 12489 Berlin — 2Leibnitz-Institut für Kristallzüchtung, Max-Born-Str. 2 12489 Berlin
Magnesium gallate is a new metal oxide semiconductor, with all advantageous properties of this material class like transparency, a large band gap of 4.9eV, as grown n-typ conductivity and a great influence of oxygen vacancies on conductivity and colour. For ARPES measurement a bulk crystal grown in the same conditions as those in [1] was used. The sample was prepared in ultra-high vacuum by sputtering and annealing until no sign of contamination was found.
A core-level of binding energy 21.6 eV was measured and attributed to Gallium. An effect of the complex inverse spinel structure is that the several bands corresponding to the inequivalent electrons cannot be distinguished. Nevertheless, a dispersion of the bands could be observed along two high-symmetry directions of the bulk Brillouin zone.
Particularly interesting is the behaviour of the electronic structure at low temperatures, where a shift and a change in shape of the valence band occurred below 30K. We attribute these findings to a order-disorder phase transition, as predicted in [2]
[1] Z. Galazka et al, Phys. Status Solidi A 212, No. 7, 1455-1460 (2015)
[2] A. Seko, K. Yuge, F. Oba, A. Kuwabara, I. Tanaka, Phys. Rev. B 73, 184117 (2006)