Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 21: Poster IB (Oxide semiconductors; II-VI and group IV semiconductors; Nanotubes and Buckyballs)

HL 21.8: Poster

Monday, March 16, 2015, 15:00–20:00, Poster B

NIR-VUV dielectric function of (Al,In,Ga)₂O₃ thin films — •Rüdiger Schmidt-Grund, Chris Sturm, Christian Kranert, Hannes Krauß, Holger von Wenckstern, Michael Bonholzer, Jörg Lenzner, and Marius Grundmann — Universität Leipzig, Institut für Experimentelle Physik II, Leipzig, Germany

We present the dielectric function spectra of (Al,In,Ga)₂O₃ thin films in a wide composition range obtained by means of spectroscopic ellipsometry in the spectral range from near NIR to vacuum UV and temperatures between 10K and room temperature [1]. By model analysis of the experimental data using a parametric model dielectric function approach we derive the refractive index dispersion in the visible spectral range and the energies of electronic transitions as a function of the composition and temperature. For In incorporation in β-Ga₂O₃ we found that the electronic structure for x<0.3 is dominantly that of monoclinic β-Ga₂O₃ and for x>0.7 that of the cubic bcc-In₂O₃ [2]. In the intermediate composition range, the DF reveals strong signatures of rh-In₂O₃ or rh-In₂O₃II. For increasing In and Al concentration we found a redshift respective a strong blueshift of the transition energies. The thin films with compositional spread were deposited on 2" a-plane sapphire and MgO substrates by means of pulsed laser deposition using segmented targets (consisting of half-segments of binary aluminum oxide respective indium oxide and binary gallium oxide) [3].

[1] R. Schmidt-Grund et al., APL 105, 111906 (2014); JAP 116, 053510 (2014). [2] C. Kranert et al., JAP 116, 013505 (2014). [3] H. von Wenckstern et al., Cryst. Eng. Comm. 15, 10020 (2013).