Regensburg 2013 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 14: Focus Session: Functionalized Semiconductor Nanowires I (jointly with HL)

DS 14.5: Topical Talk

Dienstag, 12. März 2013, 11:45–12:15, H8

III-nitride nanowires: From growth phenomena to light-emitting diodes — •Raffaella Calarco — Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany

Epitaxy in the form of freestanding vertical nanowires offers compared to planar layers the advantage that the interface between adsorbate and substrate is very small and that strain caused by lattice mismatch can elastically relax at the free sidewalls. Hence, dissimilar materials can be combined in high structural quality, and arguably the most relevant case is the growth of III-V compound semiconductors on Si substrates. We grow GaN nanowires on Si substrates by molecular beam epitaxy (MBE) and investigate nanowire properties that are essential for optoelectronic applications. Light emitting diodes (LEDs) have been fabricated using ensembles of free-standing (In, Ga)N/GaN NWs grown on Si substrates in the self-induced growth. Several characterization techniques indicate that the electroluminescence of such LEDs is governed by the differences in the individual current densities of the single-NW LEDs operated in parallel, i.e. by the inhomogeneity of the current path in the ensemble LED. In addition, the optoelectronic characterization leads to the conclusion that these NWs exhibit N-polarity and that the (In, Ga)N quantum well states in the NWs are subject to a non-vanishing quantum confined Stark effect. LEDs require NW ensembles with very homogeneous properties. Here, we present our selective area growth strategy for the synthesis of high-quality GaN NWs on prepatterned Si(111) substrates.