Dresden 2026 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 33: Nitrides I – Growth and fabrication

HL 33.2: Talk

Wednesday, March 11, 2026, 16:45–17:00, POT/0006

Phase transition regions of epitaxially sputtered TiAlN layers on TiN and AlN buffer layers — •Emine Kaynar, Florian Hörich, Jürgen Bläsing, Fabian Großmann, Usha Velpuri, Armin Dadgar, André Strittmatter, and Arne Busse — Institut für Physik, Otto-von-Guericke Universität Magdeburg, Magdeburg, Germany

For manufacturing vertical GaN-based power devices on Si substrates, it is advantageous to replace insulating AlN/AlGaN layers at the Si interface. AlN/AlGaN layers are currently required to ensure high-quality GaN on Si. TiAlN alloys offer a tunable bandgap from metallic conduction up to 6 eV and thermal robustness, making them promising alternatives to insulating Al(Ga)N buffers when epitaxial growth on Si is feasible. In this work, TiAlN layers were epitaxially grown on n-type Si (111) using TiN and AlN buffers prepared by a two-step sputtering process at growth temperatures below 900 °C. Highly crystalline cubic TiN (ω-FWHM ~ 0.3°, RMS < 1 nm) served as a conductive template. By tuning the power ratio between Ti and Al targets, Al content was systematically controlled, enabling direct mapping of the cubic-wurtzite transition. On TiN buffers, cubic TiAlN remained stable up to x ~ 0.4. On wurtzite AlN buffers, the opposite transition from wurtzite to cubic occurred as Ti incorporation increased. For all AlN-buffered samples, ω-FWHM stayed below 1° and RMS roughness remained < 5 nm. These results demonstrate precise phase control and high crystalline quality, positioning TiAlN as a strong candidate for conductive buffer layers in vertical GaN-on-Si device architectures.

Keywords: TiAlN; Epitaxial growth; Phase transition; Magnetron sputtering; Buffer layers (TiN / AlN)