Berlin 2018 – scientific programme

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DS: Fachverband Dünne Schichten

DS 17: Poster Session I

DS 17.14: Poster

Tuesday, March 13, 2018, 18:15–20:15, Poster B

Occurence of the є-phase in (In_xGa_1−x)₂O₃ and (Ga_xAl_1−x)₂O₃ thin films — •A. Werner¹, H. von Wenckstern¹, C. Sturm¹, D. Splith¹, V. Prozheeva², R. Hoelldobler¹, and M. Grundmann¹ — ¹Halbleiterphysik, Universität Leipzig, Leipzig, Germany — ²Department of Applied Physics, Aalto University, Espoo, Finland

The wide bandgap semiconductor Ga₂O₃ appears in five polymorphs of which only the so-called є-phase has a high spontaneous polarization P along its c-axis^[1]. Within heterostructures, a discontinuous change of P at the heterointerface occurs, resulting in charge accumulation. Therefore, stabilization of the є-phase within the ternary alloys (In,Ga)₂O₃ or (Ga,Al)₂O₃ is required in order to utilize the two-dimensional charge carrier gases within electronic devices. We present studies of the occurrence of the є-phase in ternary alloys of Ga₂O₃ with In₂O₃ and Al₂O₃. Samples with continuous composition spread^[2] were grown by pulsed laser deposition on (00.1) Al₂O₃. As target segments we used Ga₂O₃/In₂O₃ or Ga₂O₃/Al₂O₃. Each segment was additionally doped with tin to facilitate the formation of the є-phase^[3]. Resulting thin films were investigated by means of X-ray diffraction, transmission, energy-dispersive X-ray spectroscopy, Raman spectroscopy, and atomic force microscopy. We observed a monotonic shift of the є-reflexion in dependency of In-/Al-content; for example the (002)-reflex shifts to lower angles with increasing In-content.
^[1] M. B. Maccioni et al., Appl. Phys. Express 9, 04102 (2016).
^[2] H. v. Wenckstern et al., CrystEngComm 15, 10020 (2013).
^[3] M. Kracht et al., Phys. Rev. Applied 8, 054002 (2017).