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HL: Fachverband Halbleiterphysik

HL 44: Nitrides: Preparation and characterization II

HL 44.8: Vortrag

Donnerstag, 21. März 2024, 16:00–16:15, EW 015

Optical and chemical characterisation of In_xGa_1−xN layers and nanowire arrays — •Aidan Campbell, Mikel Gómez Ruiz, Jingxuan Kang, Lutz Geelhaar, Oliver Brandt, and Jonas Lähnemann — Paul-Drude-Institut für Festkörperelektronik, Germany

In_xGa_1−xN is an alloy with promising applications in solar water splitting, CO₂ conversion, and solar energy harvesting. Particular advantages are the tunable direct bandgap (0.7–3.5 eV), large absorption coefficient (10⁵ cm⁻¹) and high mobility. In this study, we investigate In_xGa_1−xN layers of nominal composition 0.025 < x < 0.12 grown by plasma-assisted molecular beam epitaxy. A multi-spectroscopic approach is employed using cathodoluminscence and energy dispersive X-ray spectroscopy in a scanning electron microscope. Thereby, the chemical, optical, and structural properties can be analysed and correlated for the same local region of a specimen. Factors such as dislocation density, luminous intensity, spatial homogeneity of the composition, and the morphology will be discussed, as they are key properties in optimizing growth techniques enabling high efficiency devices. The dislocation density increases by a factor of 6 over this compositional range, reaching 1.5×10⁹ cm⁻² at x=0.12. Compositional variations are evidenced by the spatial distribution of emission energies, which for different samples suggest local in-plane variations of Δ x = ± 0.005–0.008. Finally, the investigation is extended to In_xGa_1−xN nanowires obtained from these layers by top-down processing.

Keywords: InGaN; cathodoluminscence; plasma assisted molecular beam epitaxy; nanowires