Regensburg 2013 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 68: Poster Session: GaN: devices & preparation & characterization; III-V semiconductors; Photonic crystals; Semiconductor lasers

HL 68.27: Poster

Wednesday, March 13, 2013, 16:00–20:00, Poster A

Investigation of the polarity of GaN nanowires grown by MBE on AlN/Si(111) with respect to substrate polarity — •Henning Hollermann, Joerg Malindretos, and Angela Rizzi — IV. Physikalisches Institut, Georg-August Universität Göttingen, Germany

III-V materials are most promising candidates for solid-state lighting devices. However, the problem of the green-gap, the drop of the external quantum efficiency at wavelengths around 550 nm, still remains unsolved. This could be overcome by InGaN/GaN quantum well structures grown in non-polar directions. But non-polar substrates are not available with sufficiently high quality at low prices, yet.

Here GaN-based nanowires could be an alternative. While self-organized GaN nanowires, grown on non-polar Si(111) substrates show N-polarity and flat c-plane top facets, we observed pyramidal semi-polar top facets in wires selectively grown on GaN/sapphire substrates with pre-structured molybdenum masks. Those facets could serve as a base for InGaN quantum well structures with strongly reduced quantum confined Stark effect.

Since simplification of the growth process is desirable for future applications we have investigated the influence of AlN buffer-layers on the morphology and polarity of GaN nanowires grown in a self-organized manner by plasma-assisted MBE on Si(111) substrates. The aim of this study is to produce wires with semi-polar top facets in a straight-forward growth procedure. A detailed analysis of the structural properties is presented.