Berlin 2024 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 25: Oxide Semiconductors I

HL 25.2: Talk

Wednesday, March 20, 2024, 09:45–10:00, ER 325

Red shift of the absorption onset in orthorhombic κ-(In_xGa_1−x)₂O₃ alloys — •Elias Kluth¹, Alexander Karg², Martin Eickhoff², Rüdiger Goldhahn¹, and Martin Feneberg¹ — ¹Institut für Physik, Otto-von-Guericke-Universität Magdeburg, Germany — ²Institut für Festkörperphysik, Universität Bremen, Germany

The polymorphic ultra-wide band gap semiconductor Ga₂O₃ is of high research interest as it offers potential in power electronics like MOSFETs, MeSFETs or Schottky diodes as well as in solar-blind UV detectors, and many more.

While previous research has mostly focused on the stable β- or the metastable α-phase, the orthorhombic κ-Ga₂O₃ is only poorly explored. This phase is predicted to be polar with a high spontaneous polarisation, potentially even higher than GaN, making it interesting for applications such as high electron-mobility transistors (HEMTs). Alloying κ-Ga₂O₃ with indium further extends these possibilities. For a successful device implementation, an understanding of the optical properties is essential.

Here, spectroscopic ellipsometry in the visible-ultraviolet range is perfomed on κ-(In_xGa_1−x)₂O₃ with x≤0.16, grown by MBE (molecular beam epitaxy) on c-plane sapphire substrates, to obtain the complex dielectric function. An evaluation of the dielectric function yields a strong red shift in the absorption onset with increasing indium content (x).

Keywords: Ellipsometry; Gallium oxide; Dielectric function; Metal oxides; Optical properties