Regensburg 2022 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 82: Electronic Structure of Surfaces 2
O 82.7: Vortrag
Freitag, 9. September 2022, 12:00–12:15, S053
Interplay of intrinsic and extrinsic states in pinning and passivation of m-plane facets of GaN n-p-n junctions — •Lars Freter1,2, Yuhan Wang1,2, Michael Schnedler1, Jean-François Carlin3, Raphaël Butté3, Nicolas Grandjean3, Holger Eisele4, Rafal Edward Dunin-Borkowski1,5, and Philipp Ebert1 — 1Peter Grünberg Institut, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany — 2Lehrstuhl für Experimentalphysik IV E, RWTH Aachen University, 52056 Aachen, Germany — 3Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland — 4Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstr. 36, 10623 Berlin, Germany — 5Ernst Ruska-Centrum, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
Intrinsic and extrinsic pinning and passivation of m-plane cleavage facets of GaN n-p-n junctions were investigated by cross-sectional scanning tunneling microscopy and spectroscopy. On freshly cleaved and clean p-type GaN(1010) surfaces, the Fermi level is found to be extrinsically pinned by defect states, whereas n-type surfaces are intrinsically pinned by the empty surface state. For both types of doping, air exposure reduces the density of pinning states and shifts the pinning levels toward the band edges. These effects are assigned to water adsorption and dissociation, passivating intrinsic and extrinsic gap states. The revealed delicate interplay of intrinsic and extrinsic surface states at GaN(1010) surfaces is a critical factor for realizing flatband conditions at sidewall facets of nanowires exhibiting complex doping structures.