Regensburg 2022 – scientific programme

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O: Fachverband Oberflächenphysik

O 30: Semiconductor Surfaces

O 30.3: Talk

Tuesday, September 6, 2022, 11:15–11:30, S053

Reduced contact resistance to gallium nitride by plasma-assisted atomic layer deposition — •Maximilian Christis — Walter Schottky Institut, Technische Universität München

Gallium nitride is an industrially relevant III-V semiconductor that draws significant attention for a range of both established and emerging applications, including for light emitting diodes, power electronics, photocatalysis, and sensing. Established contacting schemes for GaN rely on wet-chemical surface preparations and post-metallization high-temperature (≥ 600^∘C) annealing processes, which complicate fabrication and may adversely affect device performance. Here, we present a low-temperature gas-phase process ( 200 ^∘C) that reduces the Schottky barrier height and the contact resistivity at the GaN/metal interface. In particular, we employ H2 plasma-enhanced atomic layer deposition (ALD) that creates an ultimately thin, homogeneous AlOx monolayer using oxygen from the native gallium oxide as oxidant. This AlOx coating reduces the surface band bending and results in Ohmic current-voltage characteristics for n-doped GaN contacted by Ti metal. In ongoing work, we are also exploring how the monolayer AlOx ALD approach can be applied to improve contacts to p-doped GaN in combination with high work function metals. Among the various applications that could benefit from this low thermal budget contact fabrication strategy, we are investigating how such metal/semiconductor structures impact the electrocatalytic performance of n-GaN/Pt cathodes for water splitting.