Novel low temperature solution deposition of perpendicularly orientated rods of ZnO: substrate effects and evidence of the importance of counter-ions in the control of crystallite growth

Abstract

Perpendicularly orientated ZnO rods have been grown on thin ZnO templates, from aqueous solutions of zinc acetate and hexamethylenetetraamine (HMT); growth along the c-axis of the ZnO crystallites is promoted by the presence of acetate in the bath.

One-dimensional ZnO nanostructures: Solution growth and functional properties

“…Also, the interfacial energy between crystals and substrates is usually lower than that between crystals and solution [30]. Hence, heterogeneous growth on a seeded substrate occurs at lower levels of supersaturation than nucleation and growth in homogeneous solution [49,76,83,110,111]. In other words, growth on existing seeds is more favorable than nucleation in homogeneous solution for the reason that the existing seeds bypassed the nucleation step.…”

“…Probably the most commonly used chemical agents in the existing literature for the hydrothermal synthesis of ZnO nanowires are Zn(NO 3 ) 2 and HMTA [83,84]. In this case, Zn(NO 3 ) 2 provides Zn 2+ ions required for building up ZnO nanowires.…”

“…Twinned structures are very commonly formed by wet chemical methods [83,111,[191][192][193]. Typical twinned ZnO structures [174] are shown in Fig.…”

“…Reproduced with permission pendicular to the substrate [64], even though there have been occasions when there was non-perfect c orientation [105]. The vertical alignment of the nanowire arrays is usually poor due to the polycrystalline nature of the seed [83,84]. Green et al demonstrated that ZnO nanocrystal seeds prepared by thermal Nano Res 7 decomposition of a zinc acetate precursor could give vertically well-aligned ZnO nanowire arrays [106], and the degree of alignment depended strongly on the ambient humidity level during the seeding step [89].…”

“…The seed thin film can be coated on the substrate prior to wet chemical growth [83,84]. The seed layer can be prepared in a number of ways.…”