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HL: Fachverband Halbleiterphysik

HL 30: Poster I

HL 30.10: Poster

Dienstag, 17. März 2020, 13:30–15:45, P3

Stabilization of single phase α-(Al_xGa_1−x)₂O₃ by pulsed laser deposition — •Max Kneiss, Anna Hassa, Daniel Splith, Chris Sturm, Holger von Wenckstern, Michael Lorenz, and Marius Grundmann — Universität Leipzig, Felix-Bloch-Institut für Festkörperphysik

The α-phase of Ga₂O₃ exhibits a bandgap of  5.3 eV, which is slightly larger than that of the thermodynamically stable β-phase, and crystallizes in the same rhombohedral crystal structure as α-Al₂O₃ (sapphire). The availability of cost-effective low-mismatch sapphire single crystal substrates and the possibility of heteroepitaxy without rotation domains as well as n-type doping [1] renders this phase highly promising for device applications. Bandgap engineering as well as heterostructure devices are possible by alloying with Al. However, reports on α-(Al_xGa_1−x)₂O₃ are rather scarce. We present the expitaxial stabilization of α-(Al_xGa_1−x)₂O₃ on sapphire substrates by PLD. Utilizing radially-segmented (Al_xGa_1−x)₂O₃/Ga₂O₃ targets (VCCS-PLD [2]) we were able to grow thin films in the α-phase on a- and m-plane sapphire covering the complete composition range between α-Ga₂O₃ and α-Al₂O₃. In-plane as well as out-of-plane lattice constants were determined by reciprocal space map measurements and a linear dependence on x was found. Above a critical Al-content, pseudomorphic growth was confirmed on the a-sapphire substrates. Further, the composition-dependent bandgaps as well as surface morphologies will be presented. [1] Ahmadi et al., J. Appl. Phys. 126, 160901 (2019) [2] Kneiß et al., ACS Comb. Sc. 20, 643 (2018)