Controlling the hydrothermal growth and the properties of ZnO nanorod arrays by pre-treating the seed layer

Abstract

Dense arrays of ultra-thin zinc oxide (ZnO) nanorods have been fabricated on c-oriented ZnO seed layers by hydrothermal growth, with particular emphasis on exploring the effects of annealing or plasma pre-treating the seed layer. Such pre-treatments influence the density, size and surface defects of particles within the nucleating seed layer, which impacts on the subsequent nanorod growth via sequential reaction with OH À and Zn 2+ species. Oxygen-rich defects at the seed layer surface are deduced to have particular impact -affecting both the c-axis growth rate and the photoluminescence properties of the as-grown nanorods.

Facile synthesis of oriented zinc oxide seed layer for the hydrothermal growth of zinc oxide nanorods

“…It is worth mentioning here that all XRD patterns are normalized with respect to the highest intensity peak of the relevant samples and they are vertically offset for clarity. As can be seen, diffractogram of all deposited films regardless of substrate and seeding layer are dominated by the (0002) basal plane reflections of wurtzite ZnO phase suggesting that ZnO NRs produced by hydrothermal method were grown along the c-axis (Bao et al, 1998; J. S. Kim et al, 1992;Yin et al, 2014), presumably parallel to the substrate normal. However, a slight shift of the (0002) Bragg peak to the higher 2θ angle can be distinguished for ZnO NR grown on seeded substrates compared to those of non-seeded substrates.The normalized intensity of (0002) peak was found to be always higher for ZnO NR grown on seeded substrate compared to the ZnO NR grown on non-seeded substrate, indicating that a seeded layer is indeed beneficial for controlling the c-axis texturing of the hydrothermally grown ZnO NRs.…”

“…The relative intensity of (0002) Bragg peak in the S4sample suggesting that ZnO seed layers were grown with a predominant c-axis texturing (Bao et al, 1998;Kim et al, 1992). The c-axis oriented ZnO seed layers are desirable for growing ZnO NRs vertically on the substrate surface (Yin et al, 2014).…”

“…To supplement optical bandgap measurements of nanostructured ZnO film as well as to identify defect-related emission, PL measurements were also carried out and depicted in figure 7 below. Form the literature, most PL spectra of ZnO thin film (Çopuroğlu et al, 2009;Kim et al, 2005;Yefan Chen et al, 1997) and ZnO NRs (Djuriię et al, 2007;Sun and Ashfold, 2007;Sun et al, 2006;Yin et al, 2014) show both the 380 nm UV emission feature and a much broader emission feature in the visible region (500 -600 nm) (Djuriię et al, 2007). The luminescent peak centering at~380 nm has been attributed to the near-band-edge (NBE) transition of ZnO due to the recombination of free excitons, while the luminescent features in the visible region have been attributed to the various defects, such as oxygen vacancies (V o ), oxygen interstitials (O i ) and zinc interstitials (Zn i ) etc., present in the ZnO crystal lattice (Djuriię et al, 2007;Sun and Ashfold, 2007).…”

“…In recent years, c-axis textured ZnO seed layers have been grown by various deposition methods such as, Pulsed laser deposition (PLD) (Ashfold et al, 2007), Magnetron sputtering (Yin et al, 2014), spray pyrolysis (Peir et al, 2006), Atomic laser deposition (Solís-Pomar et al, 2011), sol-gel methods (Bao et al, 1998), metal-organic chemical vapor deposition (MOCVD) (Kim et al, 1992;Tan et al, 2005) and thermal decomposition of drop-casted Zinc acetate solution (Greene et al, 2005). Among them, the drop-casting technique is a simple, cheap and environment friendly synthesis technique which requires inexpensive equipment.…”

Enhanced Antibacterial Activity of Ag Nanoparticle-Decorated ZnO Nanorod Arrays

“…In this study, ZnO nanorod arrays were fabricated on Ti wafer by a modified seed-assisted hydrothermal method [22] and Ag nanoparticles were deposited by magnetron sputtering to develop Ag nanoparticle-decorated ZnO nanorod arrays [23]. The morphology and composition of the samples were characterized by SEM, XRD, and other techniques.…”