Berlin 2024 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 27: Quantum Dots and Wires: Optics II

HL 27.2: Talk

Wednesday, March 20, 2024, 09:45–10:00, EW 202

Diameter dependence of light absorption enhancement in GaAs nanowires evidenced by photoluminescence spectroscopy — •Francisca Marín, Ijaas Mohamed, Oliver Brandt, and Lutz Geelhaar — Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e. V., Hausvogteiplatz 5-7, 10117 Berlin, Germany

Semiconductor nanowires have attracted increasing interest for photovoltaic applications, among other reasons because the absorption of light can be enhanced compared to planar layers by the appropriate geometric design of nanowire arrays. This benefit is due to the more complex coupling of light with nanowires whose dimensions are of similar scale as the light wavelength. In fact, light absorption in nanowire arrays depends sensitively on the combination of wavelength and nanowire diameter, spacing, as well as length. This phenomenon has been extensively investigated by simulations, but experimentally it is challenging to probe light absorption in nanowires, in particular in single nanowires. Here, we use photoluminescence spectroscopy to study the effect of the diameter of highly phase-pure GaAs nanowires on light absorption. Our key idea is that the nature of carrier recombination depends on carrier density, which in turn is affected by the absorption of the exciting laser light. We investigated nanowires with diameters in the range 60-160 nm and find a clear absorption enhancement with a maximum for a diameter of 80 nm.

Keywords: GaAs/(Al,Ga)As nanowires; Polytypism; Photoluminescence spectroscopy; Light absorption enhancement; Leaky-mode resonances