AVS 51st International Symposium
    Nanometer-scale Science and Technology Thursday Sessions
       Session NS2-ThM

Paper NS2-ThM1
MOCVD Synthesis of Group III Nitride Nanowires and Heterostructure Nanowires

Thursday, November 18, 2004, 8:20 am, Room 213D

Session: Nanowires I
Presenter: G.T. Wang, Sandia National Laboratories
Authors: G.T. Wang, Sandia National Laboratories
J.R. Creighton, Sandia National Laboratories
P.P. Provencio, Sandia National Laboratories
W. Pan, Sandia National Laboratories
Correspondent: Click to Email
Nanowires based on the direct bandgap semiconductor Group III nitride (AlGaInN) materials system are attractive due to their potential in novel optoelectronic applications, including LEDs, lasers, high power transistors, and sensors. To date, the primary growth methods used to synthesize GaN nanowires have been thermal evaporation or chemical vapor deposition techniques using Ga metal or GaN powder source materials in hot-wall tube reactors. These evaporation-based techniques suffer from a general lack of control, reproducibility, scalability, and the ability to produce complex heterostructures. Metal-organic chemical vapor deposition (MOCVD) has achieved widespread commercial adoption for the growth of III-nitride films and devices, with the demonstrated ability to produce complex heterostructures and doping. We have employed a MOCVD process to synthesize GaN nanowires in a standard cold-wall rotating disk reactor on 2-inch diameter wafer substrates coated with Ni catalysts. TEM, EDS, and photoluminescence studies indicate that the nanowires are single-crystalline GaN with Ni clusters at the tips, indicating growth via the vapor-liquid-solid (VLS) mechanism. The nanowires have tip diameters typically from 20-100 nm and lengths of up to tens of microns. We have also been able to synthesize core-shell heterostructure nanowires consisting of a GaN cores and various III-nitride shell materials, including AlN, InN, and AlGaN, and InGaN. The growth processes and reactor environment employed in this study are typical of those used to synthesize device-quality III-nitride films and should be scalable to larger commercial reactors and substrates. The optical and electrical properties of single nanowires and heterostructure nanowires along with the challenges of the MOCVD nanowire growth process will also be discussed.