Berlin 2024 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 1: Nitrides: Preparation and characterization I

HL 1.11: Talk

Monday, March 18, 2024, 12:30–12:45, EW 015

Phases of sputtered HfxNy: XRD, Ellipsometry and Raman spectroscopy studies — •Jona Grümbel, Christopher Lüttich, Jürgen Bläsing, Armin Dadgar, Martin Feneberg, and Rüdiger Goldhahn — Otto-von-Guericke-Universität, Universitätsplatz 2, 39106, Magdeburg,

Several phases of the binary material system HfxNy are predicted to be stable or metastable, where the thermodynamically preferred rocksalt (Fm3m) structured HfN exhibits the lowest formation energy and a metallic character. The metastable modified zincblende like (I43d) structured Hf3N4 is predicted to be semiconducting. Aiming for metallic rs-HfN, various samples were prepared via DC magnetron sputtering under varying conditions, e.g. using N2 or N2+NH3 as sputter gases. Surprisingly, samples with high ammonia flow (>10 sccm) lose their golden metallic color but exhibit typical thin film interference colors, indicating transparency in the visible spectral range. We apply UV ellipsometry and Raman spectroscopy measurements to proof, that HfxNy grown with increasing ammonia flux becomes semiconducting with an absoprtion edge of ≈ 3 eV. Annealing metallic HfN samples under ammonia atmosphere yields the same semiconductiong HfxNy phase with several narow Raman bands and an absorption edge of ≈ 3 eV as well. Surprisingly, XRD powder diffraction indicates a new phase only for the annealed sample. Detailed analysis of the optical characteristics will be presented as well as a comparison to various theroretical calculations of different HfxNy phases.

Keywords: sputter epitaxy; Hafnium nitride; Raman spectroscopy; Spectroscopic ellipsometry; New materials