Zinc oxide (ZnO), a traditional oxide semiconductor has attracted great interest because of its unique properties and multifunctional applications in recent years. ZnO appears as a major candidate for RT optoelectronic applications such as efficient short-wavelength ultraviolet light-emitting diodes, laser diodes, industrially important as a phosphor in field emissive displays, as cathodoluminescent devices, as a photocatalyst (e.g., for the oxidation of hydrocarbons), as the gain medium in UV semiconductor lasers, spin functional devices, gas sensors, transparent electronics, surface acoustic wave devices and in applications for chemical sensors and solar cells. Zinc oxide is the richest family of nanostructures among all materials both in structure and properties. It can be synthesized as nanorods, nanowires, nano belts or as anoparticles which portray improved physico chemical properties. Zinc oxide nanorods can be synthesized by various methods such as vapour liquid solid method, metal organic chemical vapour deposition, aqueous chemical growth etc. Vapour liquid solid method is highly suitable for scaled up process but required high temperature and catalyst. ZnO nanostructures are grown by the aqueous chemical growth (ACG) technique using equimolar (0.01 M) aqueous solutions of zinc nitrate and hexamethylenetetramine as precursors. The following is a typical method of manufacture.

Silicon wafer pieces and slide glass substrates are first cleaned with spectroscopic grade propanol and acetone, washed with MilliQ water and dried under N2 gas flow, placed in Pyrex glass bottles with polypropylene autoclavable screw caps containing the precursors and heated at 95C for several hours depending on substrates. Subsequently, the substrates are thoroughly washed with MilliQ water to eliminate residual salts or amino complex, and dried in air at the same temperature to get the product.