Regensburg 2013 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 91: Poster Session: Quantum dots and wires: preparation & characterization & optical properties & transport properties

HL 91.20: Poster

Thursday, March 14, 2013, 16:00–20:00, Poster A

Photoluminescence intensity and lifetime of ordered arrays of GaN nanowires with different diameter and pitch — •Christian Hauswald, Oliver Brandt, Timur Flissikowski, Tobias Gotschke, Raffaella Calarco, Lutz Geelhaar, Holger T. Grahn, and Henning Riechert — Paul-Drude-Institut für Festkörperelektronik, Berlin

Selective-area growth (SAG) of nanowires (NWs) by molecular beam epitaxy constitutes an important step towards uniform III-V NW arrays on Si. Using this approach, the diameter and length distribution of self-induced GaN NWs can be significantly reduced as compared to the growth on non-patterned substrates.

In this work, we study the influence of different diameters and pitches of selectively grown GaN NWs on their optical properties. The NWs have diameters and periods in the range of 110−260 nm and 0.3−1.0 µm, respectively. Time-integrated µ-photoluminescence (µ-PL) spectra at 10 K show a narrow linewidth, while the rather short decay times obtained by time-resolved PL measurements indicate a quite low internal quantum efficiency. We observe a monotonic decrease of the PL intensity with increasing NW diameter, although the PL decay times remain virtually constant. To investigate the origin of this effect, we use finite-element simulations to solve the Maxwell equations for the three-dimensional NW geometry. These simulations allow us to clarify whether the decrease in PL intensity is caused by a systematic change of the electromagnetic coupling to the ordered NW array.