Synthesis and characterisation of low- dimensional zinc oxide nanostructures by solution-immersion and mist-atomisation / Zuraida Khusaimi

摘要

Zinc oxide (ZnO) nanostructures on gold-seeded siliconud(Si) substrate were prepared using a low-temperatureudsolution-immersion method. Optimised ZnO structuresudwere then used as a template to grow a second layerudof ZnO nanostructures by mistatomisation method.udLow-dimensional, vertically-aligned ZnO nanorodsudwere successfully synthesised by the solution-immersionudmethod through optimisation of the reaction parameters,udsuch as concentration of precursor, ratio of stabiliser,udalignment of substrate in solution, heating medium,udgold-seeded substrates and its thickness, transitionudmetal-seeded substrates, immersion temperature andudtime, pH of precursor solution, annealing temperatureudand doping with Mg. SEM, FESEM, TGA, FTIR, XRD, EDX,udPL-Raman and I-V were the selected characterisationudtools to analyse the structural, morphological, bonding,udoptical and electrical properties of the nanostructures.udTGA and FTIR analyses gave evidence that the preparedudZnO nanostructures were pure with no traces of startingudmaterial or contamination. The results give evidence thatud6 nm thickness of gold-seeded on Si substrate immersedudfor 4 hours at 70°C in precursor concentration of 0.005ud– 0.05 M zinc nitrate hexahydrate (Zn(NO3)2.6H2O)udand hexamethylenetetramine (HMTA) at 1:1 ratio hasudsuccessfully formed (002) plane, c-axis, aligned ZnOudnanorods with diameter of approximately 60 ± 20 nm. Theudnanorods prepared at low immersion temperatures wereudfound to be readily crystalline with no additional heatudtreatment. Precursor solution of pH 6.8 and 5 producedudZnO nanorods, while at pH 9 produced ZnO flower-likeudstructures. 1 atomic % of Mg-doped ZnO nanorods wereudfound to produce the highest electrical conductivityudrelative to as-prepared ZnO, and higher doping contentudof 3, 5, 7 and 9 atomic %. PL emission spectra of ZnOudnanorods consistently produced UV (362-388 nm) andudvisible emissions (400-800 nm), confirming the formation ofuda semi-conducting ZnO.