Regensburg 2016 – scientific programme
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DS: Fachverband Dünne Schichten
DS 40: Focussed Session: Oxide Semiconductors for Device and Energy Applications I
(Joint session of DS and HL, organized by DS)
DS 40.4: Topical Talk
Thursday, March 10, 2016, 11:30–12:00, H11
Miscibility and phase separation in (InxGa1−x)2O3 — •Martin Albrecht1, Robert Schewski1, Toni Markurt1, Tobias Schulz1, Michele Baldini1, Günter Wagner1, Holger von Wenckstern2, Marius Grundmann2, Hartwin Peelaers3, Joel Varley3, and Chris Van de Walle3 — 1Institute for Crystal Growth, Berlin, Germany — 2Universität Leipzig — 3Materials Department, University of California, Santa Barbara, California, USA
Group III sesquioxides are distinguished from other wide band gap semiconductors by the fact, that they can be efficiently n-doped despite a wide band gap that ranges from 2.7 eV for In2O3 over 4.8 eV for Ga2O3 to 8.9 eV for Al2O3. Full exploitation of their properties for electronic applications requires band gap engineering formation of solid solutions. The formation of solid solutions in group III sesquioxides is challenging, since, at thermodynamic equilibrium, the binaries exhibit different thermodynamically stable structures (cubic, rhombohedral, and monoclinic) besides a significant lattice mismatch. The oxygen coordination of the metal atoms in the binary alloys is either octahedral, or mixed tetrahedral and octahedral. In this presentation we report on transmission electron microscopy studies on miscibility and phase separation in the system (InxGa1−x)2O3 grown by PLD. We identify essentially three different phases as dependent on composition, i.e. the monoclinic β-phase in the compositional range up to x=0.5, an ordered hexagonal phase in the range between x=0.5 and 0.75 and the cubic bixbyite phase at higher In contents. In atoms occupy octahedrally coordinated cation sites in the monoclinic phase.