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HL: Fachverband Halbleiterphysik

HL 66: GaN: Preparation and characterization of rods and wires

HL 66.3: Vortrag

Mittwoch, 13. März 2013, 17:30–17:45, H15

Nanometer scale correlation of optical and structural properties of individual InGaN/GaN nanorods by Scanning Transmission Electron Microscope Cathodoluminescence — •Marcus Müller¹, Gordon Schmidt¹, Peter Veit¹, Silke Petzold¹, Frank Bertram¹, Jürgen Christen¹, Steven Albert², Ana María Bengoechea-Encabo², Miguel Ángel Sánchez-Garcia², and Enrique Calleja² — ¹Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany — ²ISOM and Departamento de Ingeniería Electrónica, Universidad Politécnica de Madrid, Spain

A potential benefit of nanorods as light emitters, aside from their very high crystal quality, relies on better light extraction efficiency as compared to thin films, because of the high surface to volume ratio.
In this study we present a direct nano-scale correlation of the optical properties with the actual crystalline structure of ordered InGaN/GaN nanorods using low temperature cathodoluminescence spectroscopy in a scanning transmission electron microscope (STEM-CL). Direct comparison of the high-angle annular dark field image with the simultaneously recorded panchromatic CL mapping at 15 K reveals a weak luminescence from the bottom GaN layer. We observe the highest CL intensity in the middle of the InGaN region. The spectral position of the InGaN emission shifts continuously red from the GaN/InGaN interface (λ = 409 nm) to the NR top (λ = 446 nm) due to lattice pulling effects and InGaN partial decomposition. Additionally, optical active basal stacking faults in the GaN layer emitting at 366 nm can be found.