title: Photoluminescence Probing of Complex H2O Adsorption on InGaN/GaN Nanowires.
abstract: We demonstrate that the complex adsorption behavior of H2O on InGaN/GaN nanowire arrays is directly revealed by their ambient-dependent photoluminescence properties. Under low-humidity, ambient-temperature, and low-excitation-light conditions, H2O adsorbates cause a quenching of the photoluminescence. In contrast, for high humidity levels, elevated temperature, and high excitation intensity, H2O adsorbates act as efficient photoluminescence enhancers. We show that this behavior, which can only be detected due to the low operation temperature of the InGaN/GaN nanowires, can be explained on the basis of single H2O adsorbates forming surface recombination centers and multiple H2O adsorbates forming surface passivation layers. Reversible creation of such passivation layers is induced by the photoelectrochemical splitting of adsorbed water molecules and by the interaction of reactive H3O+and OH-ions with photoactivated InGaN surfaces. Due to electronic coupling of adsorbing molecules with photoactivated surfaces, InGaN/GaN nanowires act as sensitive nanooptical probes for the analysis of photoelectrochemical surface processes.
authors.affiliation: Airbus Group Innovations , D-81663 Munich, Germany.
authors.forename: Konrad
authors.initials: K
authors.lastname: Maier
authors.affiliation: Airbus Group Innovations , D-81663 Munich, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Helwig
authors.affiliation: Airbus Group Innovations , D-81663 Munich, Germany.|Department of Applied Sciences and Mechatronics, Munich University of Applied Sciences , D-80335 Munich, Germany.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Müller
authors.affiliation: Institute of Experimental Physics I, Justus-Liebig-University Giessen , D-35392 Giessen, Germany.
authors.forename: Pascal
authors.initials: P
authors.lastname: Hille
authors.affiliation: Institute of Experimental Physics I, Justus-Liebig-University Giessen , D-35392 Giessen, Germany.
authors.forename: Jörg
authors.identifier: 0000-0002-9781-4574
authors.initials: J
authors.lastname: Teubert
authors.affiliation: Institute of Experimental Physics I, Justus-Liebig-University Giessen , D-35392 Giessen, Germany.|Institute of Solid State Physics, University of Bremen , D-28359 Bremen, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Eickhoff
mesh_terms: D000327:Adsorption; D005708:Gallium / Q000737:chemistry*; D006878:Hydroxides / Q000737:chemistry; D007204:Indium / Q000737:chemistry*; D008027:Light; D049449:Luminescence; D053770:Nanowires / Q000737:chemistry*; D009584:Nitrogen / Q000737:chemistry*; D011522:Protons; D012666:Semiconductors; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
chemical_list: D006878:Hydroxides; D011522:Protons; D007204:Indium; D014867:Water; C031356:hydroxide ion; D005708:Gallium; D009584:Nitrogen
keywords: H2O adsorption; III-Nitride semiconductors; nanowires; photoelectrochemical water splitting; photoluminescence; surface passivation; surface recombination