Controlled growth of vertically aligned ZnO nanowires with different crystal orientation of the ZnO seed layer

Abstract

A novel synthesis and growth method achieving vertically aligned zinc oxide (ZnO) nanowires on a silicon dioxide (SiO(2)) coated silicon (Si) substrate is demonstrated. The growth direction of the ZnO nanowires is determined by the crystal structure of the ZnO seed layer, which is formed by the oxidation of a DC-sputtered Zn film. The [002] crystal direction of the seed layer is dominant under optimized thickness of the Zn film and thermal treatment. Vertically aligned ZnO nanowires on SiO(2) coated Si substrate are realized from the appropriately thick oxidized Zn seed layer by a vapor-solid growth mechanism by catalyst-free thermal chemical vapor deposition (CVD). These experimental results raise the possibility of using the nanowires as functional blocks for high-density integration systems and/or photonic applications.

Effect of pressure and Al doping on structural and optical properties of ZnO nanowires synthesized by chemical vapor deposition

“…Since metal catalysts are not used, the growth process follows a vapor-solid growth mechanism instead of the conventional vapor-liquid-solid mechanism [7]. In the high growth temperature (900 1C), oxygen poor, low pressure environment, more of the Zn vapors remain unoxidized.…”

“…In addition, growth and characterization of ZnO-based nanostructures have been actively investigated, and several one dimensional (1D) nanoscale devices have been demonstrated [4][5][6][7][8]. In both cases, the most popular means to synthesize these ZnO nanostructures is chemical vapor deposition (CVD) [7,8].…”

“…In addition to UV emission from excitonic recombination near the band edge, a broad visible wavelength ("green") emission band near 2.4 eV is often observed [3][4][5][6][7][8][9][10][11][12][13]. This green emission band, which is generally associated with oxygen vacancy defect levels and can be stronger than band edge emission in ZnO nanostructures [4][5][6]14], is mediated by energy transfer from bound excitons [15].…”

Nanostructured ZnO Materials: Synthesis, Properties and Applications

“…Other works report the thermal CVD growth of vertically aligned ZnO nanowires on silicon/silicon dioxide substrates, with the use of a seed layer prepared by thermal treatment of a 30-nm-thick sputtered Zn layer [66]. The as-grown Zn film is thermally crystallized and oxidized to ZnO in a furnace at 400 C in ambient air, forming a layer along the (002) plane.…”

Synthesis of Vertically Aligned ZnO Nanorods on Ni-Based Buffer Layers Using a Thermal Evaporation Process

“…Buffer layers of Au, Sn, [11][12][13] Ni, 14 Cu, 15 etc. and a self-catalyzing ZnO layer 9,16,17 have been applied. Au, GaN, and ZnO have been recognized as the most effective materials for buffer layers.…”