Regensburg 2025 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 20: Poster I

HL 20.10: Poster

Tuesday, March 18, 2025, 10:00–12:30, P3

Passivation Protection Layers for Highly efficient Multi-Absorber Devices for Photoelectrochemical Solar Fuel Production — •Negin Mogharehabed¹, Mohammad Amin Zare Pour^1,2, Jennifer Velázquez Rojas³, Christian Höhn³, Roel van de Krol³, Thomas Hannappel², and Agnieszka Paszuk¹ — ¹Paszuk Group, Technische Universität Ilmenau, Germany — ²Fundamentals of Energy Materials, Technische Universität Ilmenau, Germany — ³Institute for Solar Fuels, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Germany

In photoelectrochemical cells with the highest solar-to-hydrogen conversion efficiencies, the heterointerface between a III-V top layer and a metal oxide protection layer should be optimized to minimize charge carrier losses. Using photoemission spectroscopy, we study the TiO2/InP(100) heterointerface as a function of InP surface preparation and Ti precursor.

InP(100) substrates were prepared with either a well-ordered, phosphorus-terminated surface in a metal-organic chemical vapor deposition (MOCVD) reactor or with a thin oxide layer. TiO2 was deposited via atomic layer deposition (ALD) using either titanium tetrachloride (TiCl4) or titanium isopropoxide (TTIP) as the Ti precursor, along with water as the co-reactant.

Depending on the Ti precursor and the InP surface preparation, we observed either a nucleation delay or acceleration and differences in the band alignment. Layers grown with the TTIP precursor showed the presence of Ti³⁺ states, which may act as trap centers.

Keywords: metal oxide passivation layer; titanium dioxide; III-V semiconductors; photoelectrochemistry; X-ray photoelectron spectroscopy