Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 83: Focus Session: Oxide semiconductors II (DS with HL)

HL 83.4: Talk

Thursday, March 19, 2015, 16:00–16:15, H 2032

Structural properties and phonon modes of (Al_xGa_1−x)₂O₃ — •Christian Kranert, Marcus Jenderka, Jörg Lenzner, Michael Lorenz, Holger von Wenckstern, Rüdiger Schmidt-Grund, and Marius Grundmann — Universität Leipzig, Institut für Experimentelle Physik II, Semiconductor Physics Group, Leipzig, Germany

We present a combined X-ray diffraction and Raman scattering study on a 2-inch diameter thin film with a continuous composition spread (CCS) [1] in comparison to bulk-like ceramic samples. For the composition range for which the ceramic materials exclusively exhibit the β-modification, we obtained their individual lattice parameters as a function of the composition. These comply with Vegard’s rule. We further investigated these samples by Raman spectroscopy. The obtained phonon energy dependencies on the composition in the β-phase are found to be linear as well.

The CCS approach for the thin films allows us to determine its properties for virtually any composition within the composition range of the sample. The comparison to the ceramic samples shows a reduced out-of-plane lattice parameter for the thin films. Despite that, the phonon energies show a good agreement to the bulk values.

The material β-Ga₂O₃ is of interest for deep UV optoelectronics. Alloying with Al₂O₃ increases its band gap, which makes the alloy (Al,Ga)₂O₃ suitable for an application in Ga₂O₃-based heterostructures or as barrier material for Ga₂O₃ quantum wells.

[1] H. von Wenckstern et al., CrystEngComm 15, 10020 (2013)