Surface Polarity and Shape‐Controlled Synthesis of ZnO Nanostructures on GaN Thin Films Based on Catalyst‐Free Metalorganic Vapor Phase Epitaxy

Abstract

Surface polarity and shape‐controlled ZnO nanostructures are synthesized on GaN thin films using metalorganic vapor phase epitaxy (MOVPE). By adjusting the growth parameters from Zn‐rich at low temperature to O‐rich at high temperature, morphology of ZnO nanostructures was tuned from nonpolar, smooth‐surfaced ZnO nanorod nanowall networks to O‐polar, stacked pyramid‐structured ZnO nanorods.

Temperature-dependence cathodoluminescence of ultra-sharp ZnO nanopagoda arrays

“…From the above results, the growth processes of ZnO nanopagodas with amount of reaction precursors (250 mL) and long reaction time (12 h) can be used to repair the surface defect from ZnO nanorod arrays. In contrast to previous reports, ultra-sharp ZnO nanopagodas exhibit a stronger UV emission from band gap, which is attributed to their smooth-surfaced and high crystal quality [31,32]. In addition, the present work used low concentration zinc precursors (5 mM) to avoid the excessive supply of Zn ion, which would lead to the formation of the oxide vacancies.…”

Catalyst-free synthesis and cathodoluminescent properties of ZnO nanobranches on Si nanowire backbones

“…The existence of the ZnO shell layers on the Si nanowire backbones (dark region) was also confirmed by the high-resolution TEM (HRTEM) image taken at the junction of the branched NWHSs Although ZnO nanobranches grow out of the entire Si nanowire surface at temperatures below 500°C, no ZnO nanostructure was formed on the bare Si nanowires at temperatures above 800°C [ Fig. 8,31,32 By exploiting the growth behavior of ZnO nanobranches with regards to the existence of the ZnO shell, ZnO/Si nanowire networked structures were produced [ Fig. Similar growth behavior has been observed previously during the growth of ZnO on bare Si and SiO 2 /Si substrates, and this phenomenon can be understood in that nucleation is limited at high temperature.…”

“…8 For both TEM and CL characterizations, the branched NWHSs were dispersed into an ethanol solution, and the wire-containing ethanol droplets were then deposited on carbon-coated copper grids. To investigate the optical properties of the ZnO/Si branched NWHSs, cathodoluminescence (CL) measurements were performed at room temperature using a Gantan Mono-CL3 system (attached to an S-4300 FE-SEM, Hitachi), with an accelerating voltage of 8 kV.…”

“…1,2 The ability to control the structure, 2-5 morphology, [6][7][8] and composition [9][10][11][12][13][14] of these building blocks may allow engineers to tailor their electrical and optical properties. 1,2 The ability to control the structure, 2-5 morphology, [6][7][8] and composition [9][10][11][12][13][14] of these building blocks may allow engineers to tailor their electrical and optical properties.…”

Effect of growth conditions on zinc oxide nanowire array synthesized on Si (100) without catalyst

“…Among them nanowires and nanorods grown by vapor deposition techniques as well as solution based methods have attracted much attention because they provide a direct path for charge transport [17] and have high surface to volume ratio (high surface area). Pulsed laser deposition (PLD) [18], chemical vapor deposition (CVD) [19], metal organic chemical vapor deposition (MOCVD) [20], and thermal evaporation are vapor phase deposition techniques for growth of ZnO nanowires and nanorods. Among thermal evaporation methods, chemical vapor transport and condensation (CVTC) is an extensively used, simple, and low cost method which can provide large quantity and high crystalline quality products.…”