Dresden 2014 – scientific programme

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DS: Fachverband Dünne Schichten

DS 30: Focus Session: Emerging oxide semiconductors II (jointly with HL, DF, O)

DS 30.11: Talk

Wednesday, April 2, 2014, 18:15–18:30, POT 081

Stability of low-index bcc-In₂O₃ surfaces under O-Rich-, In-Rich-, and Sn-doping molecular beam epitaxy conditions: An Experimental Study — •Oliver Bierwagen^1,2, Patrick Vogt¹, and James S. Speck² — ¹Paul-Drude-Institut, Berlin,Germany. — ²University of California, Santa Barbara, USA.

Molecular beam epitaxy of bixbiyte In₂O₃ on (001) oriented ZrO₂:Y (YSZ) substrates typically results in {111} faceted surfaces whereas on (111) smooth films are obtained [1]. This behavior has been explained by theory calculations that found the surface free energies of low index bixbiyte surfaces to increase from (111) to (011) to (001) surfaces [2]. On the other hand, it was found that In-rich growth conditions [1] or high Sn-doping [6] lead to the formation of smooth, unfaceted (001) In₂O₃ films on YSZ(001). These results are in-line calculations of stoichiometry-dependent surface free energy [5]. Our experimental study of In₂O₃ on YSZ(001), (011), (111) grown by MBE under O-rich, In-rich and high Sn-doping conditions suggest the following relative surface free energies: (111) lowest under all conditions, (001) significantly lowered by In-rich conditions and Sn-doping. A flat (011) surface was not observed suggesting a higher surface free energy than predicted by theory. Our experimental results compare well to theory of [5]. [1] Bierwagen, Appl. Phys. Lett. 95, 262105 (2009). [2] Walsh and Catlow, J. Mater. Chem. 20, 10438 (2010). [4] Bierwagen and Speck, J. Appl. Phys. 107, 113519 (2010). [5] Agoston and Albe, Phys. Rev. B 84, 045311 (2011). [6] Taga, Jpn. J. Appl. Phys. 37, 6585 (1998).