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Proceedings Paper

Investigation of the electrical activity of V-defects in GaN using scanning force microscopy
Author(s): André Lochthofen; Wolfgang Mertin; Gerd Bacher; Lutz Hoeppel; Stefan Bader; Jürgen Off; Berthold Hahn
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Paper Abstract

We report on the characterization of V-defects in GaN-based heterostructures via scanning force microscopy techniques. The diameter and density of the V-defects are found to strongly depend on growth thickness and temperature of the top layer, respectively, while no correlation between the V-defect formation and the type of doping could be identified. Kelvin probe force microscopy measurements revealed for both, n- and p-doped GaN top layers, a decrease of the Kelvin voltage within the V-defects, which indicates an enhanced work function of the facets of the V-defects with respect to the planar surface. Surprisingly, an increase of the current flow within the V-defects is found by conductive atomic force microscopy in case of the n-doped top layer, while current flow into the V-defect is suppressed for the p-doped top layer. For a consistent explanation of these results we suggest a model, which is based on an enhanced electron affinity of the {10-11}-surfaces within the V-defects as compared to the planar (0001)-surface.

Paper Details

Date Published: 16 February 2009
PDF: 10 pages
Proc. SPIE 7216, Gallium Nitride Materials and Devices IV, 721610 (16 February 2009); doi: 10.1117/12.808992
Show Author Affiliations
André Lochthofen, Univ. Duisburg-Essen (Germany)
Wolfgang Mertin, Univ. Duisburg-Essen (Germany)
Gerd Bacher, Univ. Duisburg-Essen (Germany)
Lutz Hoeppel, OSRAM Opto Semiconductors GmbH (Germany)
Stefan Bader, OSRAM Opto Semiconductors GmbH (Germany)
Jürgen Off, OSRAM Opto Semiconductors GmbH (Germany)
Berthold Hahn, OSRAM Opto Semiconductors GmbH (Germany)

Published in SPIE Proceedings Vol. 7216:
Gallium Nitride Materials and Devices IV
Hadis Morkoç; Cole W. Litton; Jen-Inn Chyi; Yasushi Nanishi; Joachim Piprek; Euijoon Yoon, Editor(s)

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