Controlled Growth of Parallel Oriented ZnO Nanostructural Arrays on Ga₂O₃ Nanowires

Abstract

Novel hierarchical ZnO-Ga 2 O 3 nanostructures were fabricated via a two stage growth process. Nanowires of Ga 2 O 3 were obtained in the first stage by the vapor-liquid-solid mechanism and used as the foundation for growth of self-assembled, ordered arrays of ZnO nanostructures during the second stage by the vapor-solid mechanism. The resulting hierarchical nanostructures had a final morphology consisting of nanobrushes (NBs) with Ga 2 O 3 as the core and ZnO as the branches self-assembling symmetrically in six equiangular directions around the core. Characterization of the NBs was performed by scanning and transmission electron microscopies, energy dispersive spectroscopy, and Fourier transform infrared spectroscopy. The mechanism of formation is discussed together with potential applications, among which is the aligned growth of vertically aligned ZnO nanorods that are touted for optoelectronics. Advantages of this alignment method are lower temperature growth, reduced amount of thermally induced defects, and absence of catalytic impurities.

Self-assembled synthesis of hierarchical Zn2GeO4 core–shell microspheres with enhanced photocatalytic activity

“…[11][12][13] Recent examples of such hierarchical materials include spindles, 14 multipods, 15 stars, 16 dendrites 17 and other abundant structures. [18][19][20][21] As a typical example, inorganic hierarchically microspherical structures, consisting of one or two-dimensional arrangement of nanoparticles, possess the unique merits of large specific surface area, high concentration of porosity, rich active sites and large void space. [22][23][24][25][26] To date, these materials, including metals, 27,28 carbides, 29,30 oxides, 31 sulphides, 32,33 and selenides, 34 have been fabricated via a variety of growth techniques.…”

Interaction of functionalized Ga2O3 NW-based room temperature gas sensors with different hydrocarbons

“…Infrared data for AC adsorbed on NRs, obtained under conditions different from those used here, are reported elsewhere [9]. The major difference between NRs and NWs is that the NRs expose predominantly the (1 0 0) surface whereas NWs involve higher-index planes [13]. On the (1 0 0), in the absence of defects, fivefold-coordinated octahedral Ga atoms are the only unsaturated cation sites; however, more reactive threefold-coordinated tetrahedral Ga sites are found on other surfaces.…”

“…Briefly a sensor, consisting of an interdigitated array of Pt electrodes, was fabricated using heavily doped (<0.01 Ohm-cm) Si(1 0 0) substrates with a 250 nm thick thermal oxide. The device was then covered with a gold layer for further Ga 2 O 3 NW growth by the vapor-liquid-solid method at 900 • C in a horizontal furnace [13]. We did not perform surface area measurements to estimate NW surface coverage during the adsorption because there is an insufficient quantity of NWs on each substrate piece and because the NWs are not free-standing but in contact with the substrate.…”

The Growth of Semiconductor and Dielectric Nanowires and Nanowire Arrays and their Plasmonic Applications.

“…The first step involved the growth of Ga 2 O 3 nanowires (NW) by the VLS method on a Si substrate, as described above, and the second step involved the growth of ZnO nano arrays on the resultant Ga 2 O 3 NW obtained in the first step, with no metal catalyst used. This growth was by the VS growth mechanism [11]. For this step, an alumina boat, containing Zn powder and a silicon substrate with the Ga 2 O 3 NWs from the first stage, were loaded into a horizontal quartz tube furnace.…”