Regensburg 2016 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 15: Quantum Dots and Wires: Fabrication and Devices

HL 15.10: Vortrag

Montag, 7. März 2016, 17:45–18:00, H16

Selective area growth of GaAs nanowires combining high vertical yield and desirable morphology — •Hanno Küpers, Abbes Tahraoui, Ryan B. Lewis, Henning Riechert, and Lutz Geelhaar — Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin

The Ga-assisted growth of GaAs nanowires (NWs) is a promising way to integrate III-V materials with Si. Toward this goal, selective area NW growth on an oxide mask by molecular beam epitaxy has been widely investigated, focusing mainly on obtaining high vertical NW yields rather than optimal NW morphologies. Key requirements for high NW yields are a high mask quality and a low V/III ratio, however, NWs grown under these conditions exhibit large diameters and a high degree of tapering, both undesired properties for applications relying on a core-shell geometry. In this study we present a two-step growth approach which results in high vertical yields with small diameters and negligible tapering: First, NWs start to grow under growth conditions optimized for a high vertical yield. Second, after some time the growth conditions are changed in order to shape the morphology of the growing NWs. Even though the V/III ratio is increased the NW growth remains stable and does not cease. This growth approach enables the growth of NW ensembles with a vertical yield of exceeding 70%, diameters of 50 nm and tapering of below 0.4%.