Substrate effect on morphology and photoluminescence from ZnO monopods and bipods

Abstract

A simple wet chemical bath deposition has been successfully deployed to fabricate zinc oxide (ZnO) nanostructures. For substrate free growth, the nanostructure is spindle like monopods. But when the nanostructures grow on the glass and quartz substrates, they are bipods (two monopods joined together base to base). Variation in the size of the spindles of the monopods and bipods and the particle size was observed due to the strain exists in the thin film due to lattice mismatch at the interface of the thin film and the substrates. The X-ray diffraction (XRD) and selected area diffraction results confirmed the hexagonal unit cell structures of the monopods and bipods. Also the growth rates of various planes are different and the growth is anisotropic. The substrate free grown monopods show visible photoluminescence (PL) at 421 nm. But the emission gets shifted by 3 and 6 nm for ZnO thin film deposited on quartz and glass substrates respectively due to interfacial strain. In case of ZnO on quartz substrate a strong ultra-violet (UV) peak was observed at 386 nm due to band edge transition. These emissions are also accompanied by few weaker emission peaks due to various defect related transition.

Influence of annealing temperature on morphological, optical and UV detection properties of ZnO nanowires grown by chemical bath deposition

“…The second major peak appeared at around 390 nm in Figure 8 The green emission ~530 nm (peak 3 and peak 4 respectively for the cases annealed at 400℃ and at 450℃) was also observed, possibly due to the recombination of electrons at the conduction band with holes trapped in oxygen-related defects [48,49], especially in the singleionized oxygen vacancy (V O + ) [50]. The broad emission peak at ~450 nm (2.7 eV) in Figure 8b can be attributed to the electronic transition from the donor level Zn i to the acceptor level V Zn , which is about 2.6 eV [47].…”

“…It is worth mentioning all chemical materials were purchased from Merk Co., Germany, and used as received without further purification. In the synthesizing process, 50 …”

Review on Wet Chemical Growth and Anti-bacterial Activity of Zinc Oxide Nanostructures

“…By selective capping of the various facets of ZnO crystals it is possible to grow unidirectional growth of ZnO [34,35]. By varying the growth temperature and the growth duration the structure changes from nanorods, to monopods, bipods and nanoprism-like structures ( Figure 3) [36]. The pH of the solution is a key control factor of the growth rate of ZnO.…”

Single-pot ZnO nanostructure synthesis by chemical bath deposition and their applications

“…In the presence of the ammonium hydroxide the reaction mechanism will change, leading to the formation of the zinc ammonium complex and ZnO. The reactions involved in the formation of ZnO in the presence of ammonium hydroxide are: face, [89].…”