Growth of Epitaxial Needlelike ZnO Nanowires on GaN Films

Abstract

Epitaxial needlelike ZnO nanowires were grown vertically over an entire epi-GaN/sapphire substrate at 550°C by low-pressure vapor phase deposition without employing any metal catalysts. A two-step oxygen injection process is the key of successful synthesis. The length of ZnO wires was up to 3.0 m. The diameters of the roots and tips of the ZnO nanowires were around 80-100 and 15-30 nm, respectively. X-ray diffraction showed the epitaxial orientation relationship between ZnO and GaN as ͓001͔ ZnO //͓001͔ GaN along the normal to the plane, and ͓100͔ ZnO //͓100͔ GaN along the in-plane direction, consistent with the selective area electron diffraction pattern taken at the ZnO/GaN heterointerface. High-resolution transmission electron microscopy confirmed that nanowire was a single crystal. A room-temperature photoluminescence spectrum of the wires revealed a low concentration of oxygen vacancy in the ZnO nanowires and showed high optical quality.

Effect of sputtered films on morphology of vertical aligned ZnO nanowires

“…The low-magnification image reveals that the average diameter of the grown nanowire was about 80 nm and uniform throughout its length. The same height and the homogeneous size indicate that the nucleation of ZnO nanowire growth centers was very fast [29]. The synthesis of ZnO nanowires results in a preferential growth direction along the c-axis of ZnO normal to the substrate surface.…”

Enhanced Photocurrent from CdS Sensitized ZnO Nanorods

“…The above is determined by the temperature of the reaction medium. Usually, hexagonal tips are formed at higher temperature [7], however, we got a mixture of hexagonal and sharp tipped nanorods. Fig.…”

Zinc Oxide Nanostructures: Synthesis and Properties

“…Synthesis utilizing VS process is usually capable of producing a rich variety of nanostructures, including nanowires, nanorods, nanobelts and other complex structures. [29][30][31]34,[50][51][52][53][54][55][56][57][58][59][60][61][62][63][64] In a typical VS process, complex ZnO nanostructures such as nanohelixes and nanobelts were synthesized by Kong et al 34 (Fig. 1a & b).…”

“…Although the vertical alignment of ZnO nanostructures can be assisted by an electric field, 80 in most cases, the alignment is realized by lattice matching between ZnO and the substrate. Several types of epitaxy substrates have been utilized, including sapphire, 14,48,74 GaN, 37,60,61,72,74 ZnO film coated substrate, 71 SiC 47 and Si substrate. [81][82][83][84] Yang et al have grown vertical aligned ZnO nanowires array on sapphire ) 0 2 11 ( plane, as shown in Fig.…”