title: Optical Emission of Individual GaN Nanocolumns Analyzed with High Spatial Resolution.
abstract: Selective area growth has been applied to fabricate a homogeneous array of GaN nanocolumns (NC) with high crystal quality. The structural and optical properties of single NCs have been investigated at the nanometer-scale by transmission electron microscopy (TEM) and highly spatially resolved cathodoluminescence (CL) spectroscopy performed in a scanning transmission electron microscope (STEM) at liquid helium temperatures. TEM cross-section analysis reveals excellent structural properties of the GaN NCs. Sporadically, isolated basal plane stacking faults (BSF) can be found resulting in a remarkably low BSF density in the almost entire NC ensemble. Both, defect-free NCs and NCs with few BSFs have been investigated. The low defect density within the NCs allows the characterization of individual BSFs, which is of high interest for studying their optical properties. Direct nanometer-scale correlation of the CL and STEM data clearly exhibits a spatial correlation of the emission at 360.6 nm (3.438 eV) with the location of basal plane stacking faults of type I1.
authors.affiliation: †IV. Physikalisches Institut, Georg-August-Universität Göttingen, 37077 Göttingen, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Urban
authors.affiliation: ‡Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, 39106 Magdeburg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Müller
authors.affiliation: ‡Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, 39106 Magdeburg, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Karbaum
authors.affiliation: ‡Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, 39106 Magdeburg, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Schmidt
authors.affiliation: ‡Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, 39106 Magdeburg, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Veit
authors.affiliation: †IV. Physikalisches Institut, Georg-August-Universität Göttingen, 37077 Göttingen, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Malindretos
authors.affiliation: ‡Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, 39106 Magdeburg, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Bertram
authors.affiliation: ‡Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, 39106 Magdeburg, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Christen
authors.affiliation: †IV. Physikalisches Institut, Georg-August-Universität Göttingen, 37077 Göttingen, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Rizzi
keywords: Gallium-nitride; basal plane stacking fault; cathodoluminescence spectroscopy; nanocolumn; scanning transmission electron microscopy; selective area growth