High-yield synthesis of ZnO nanowire arrays and their opto-electrical properties

Abstract

In this article, ZnO nanostructures were synthesized via the hydrothermal method which used ZnCl(2) and HMTA mixed solution as the precursor. A multistep growth was adopted to improve the growth restriction of a closed system, not only the length but also the aspect ratio were increased with steps of growth, and the shape of nanorods maintained integrity. Furthermore, photoluminescence spectra which have the near-band-edge-emission (∼3.37 eV) and defect-related emission show the optical properties of ZnO nanostructures. The defect-related emission intensity was greatly enhanced with the increasing surface area of ZnO nanowires. The level of the OH group was attributed to the yellow-light emission (∼580 nm) and the red-shift phenomenon. In addition, we fabricated two types of ultraviolet photodetectors: a single nanowire device and a nanowire-array device, operating at a low bias (less than 5 mV). With the lower energy consumption and the weaker persistent photoconductive effect, our ultraviolet photodetectors have better performance, exhibiting a short response time and higher sensitivity.

Influence of annealing ambient on the structure, photoluminescence and photocatalytic activity of low temperature grown ZnO nanowires

“…Among them, hydrothermal method is an economical and low-temperature fabrication method. However, the large defect concentration is inevitable for the synthesis of ZnO nanowires during a low-temperature hydrothermal route, such as surface defects, near surface traps and surface adsorbed species [5,6], which maybe result in passivation or inefficient electron transport [7]. In general, a post annealing treatment is a effective way to modify the surface defects.…”

Hierarchical Growth of ZnO Particles by a Hydrothermal Route

“…The authors suggested growth occurred from solutions supersaturated with respect to Zn(OH) 4 2-. 25 The occurrence of a hexagonal prismatic morphology [26][27][28][29][30][31] is generally assumed to be a consequence of surface energy effects favouring the development of {10-10} and {0001} crystal faces.…”

Effect of reaction temperature on surface morphology and photoelectric properties of ZnO grown by hydrothermal method in mixed solvent

“…A portion of holes are drifted by the surface electric field in the depletion layer. The migrated holes can neutralize the surface adsorbed oxygen and resulting in the decrease of depletion layer near the surface [27].…”

“…The fast UV response may be attributed to the adsorption and photodesorption of oxygen molecules on the surface of ZnO thin films. Before UV irradiation, oxygen molecules are adsorbed onto the surfaces of ZnO thin film by capturing free electrons from the ZnO and forming a low-conductivity depletion layer near the surface [27]. …”