title: Assessment of Polarity in GaN Self-Assembled Nanowires by Electrical Force Microscopy.
abstract: In this work, we demonstrate the capabilities of atomic force microscopies (AFMs) for the nondestructive determination of the polarity of GaN nanowires (NWs). Three complementary AFMs are analyzed here: Kelvin probe force microscopy (KPFM), light-assisted KPFM, and piezo-force microscopy (PFM). These techniques allow us to assess the polarity of individual NWs over an area of tens of μm(2) and provide statistics on the polarity of the ensemble with an accuracy hardly reachable by other methods. The precise quantitative analysis of the tip-sample interaction by multidimensional spectroscopic measurements, combined with advanced data analysis, has allowed the separate characterization of electrostatic and van der Waals forces as a function of tip-sample distance. Besides their polarity, the net surface charge density of individual NWs was estimated.
authors.affiliation: Materials Science Institute, University of Valencia , P.O. Box 22085, E46071 Valencia, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Minj
authors.affiliation: Materials Science Institute, University of Valencia , P.O. Box 22085, E46071 Valencia, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Cros
authors.affiliation: Materials Science Institute, University of Valencia , P.O. Box 22085, E46071 Valencia, Spain.
authors.forename: N
authors.initials: N
authors.lastname: Garro
authors.affiliation: Facultad de Química, Departamento de Física, Universidad de Murcia , 30100 Murcia, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Colchero
authors.affiliation: Université Grenoble Alpes, INAC-SP2M , F-38000 Grenoble, France.|CEA, INAC-SP2M , F-38054 Grenoble, France.
authors.forename: T
authors.initials: T
authors.lastname: Auzelle
authors.affiliation: Université Grenoble Alpes, INAC-SP2M , F-38000 Grenoble, France.|CEA, INAC-SP2M , F-38054 Grenoble, France.
authors.forename: B
authors.initials: B
authors.lastname: Daudin
keywords: GaN; Kelvin probe force microscopy; Nanowire; piezo force microscopy; polarity; surface photovoltage