Regensburg 2004 – scientific programme

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HL: Halbleiterphysik

HL 12: Poster I

HL 12.52: Poster

Monday, March 8, 2004, 16:30–19:00, Poster A

Controlled fabrication of well-aligned single-crystalline ZnO nanowires — •Hongjin Fan, Florian M. Kolb, Roland Scholz, Margit Zacharias, and Ulrich Gösele — Max-Planck-Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany

Fabrication of ZnO nanowires with controlled morphology, size, and orientation is essential for their applications in room-temperature UV nanolasers. By using a vapor transport and condensation process based on vapor-liquid-solid (VLS) mechanism, ZnO nanowire arrays were successfully synthesized on sapphire substrates. Electron microscopy investigations show that the nanowires are aligned mainly vertical to the sapphire substrate, having heights up to 8 µm and diameters of 30–150 nm. The nanowires were identified to be single-crystalline hexagonal wurtzite ZnO and unidirectioned along ⟨0001⟩. They are structurally uniform without observable dislocations or an amorphous sheath. In order to tune the diameter and length of the nanowires, the thickness of the catalyst Au film and growth time were varied respectively. In addition, when the Au particles on the substrate were predefined, the position and density of the ZnO nanowire arrays can be subsequently controlled. Room-temperature photoluminescence measurements show a sharp UV emission peak near the band gap of ZnO at 3.36 eV, and a very broad green emission associated with ionized oxygen vacancy defects.