Author : Lee Huat Kelly Koh
Publisher :
ISBN 13 :
Total Pages : 214 pages
Book Rating : 4.:/5 (795 download)
Book Synopsis Novel Synthesis and Fabrication of ZnO Thin Films Via an Anhydrous Sol-gel Route by : Lee Huat Kelly Koh
Download or read book Novel Synthesis and Fabrication of ZnO Thin Films Via an Anhydrous Sol-gel Route written by Lee Huat Kelly Koh and published by . This book was released on 2008 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, the aim to synthesise nano-sized zinc oxide particles in the form of thin films by using a novel anhydrous sol-gel technique was proposed, developed and demonstrated. The sol-gel was prepared using anhydrous zinc acetate [Zn(C2H3O2)2], monoethanolamine [H2NC2H4OH ] and isopropanol. The zinc oxide thin films were fabricated on soda-lime and fused silica substrates from both single- and multi- step spin-coating depositions. A range of widely reported zinc acetate concentrations, annealing temperatures and spin-coating speeds was chosen to characterise and study the various effects that these parameters have on the crystallographical, morphological, optical, electronic and electrical properties. The mean crystallite sizes and other structural properties (such as micro-strain and degree of crystallinity) were estimated using x-ray diffraction analysis. In combination with scanning electron microscopy, the increase in particle size was observed to be non-linear, changing from that of individual growth to that of particle conglomeration at higher precursor concentration and annealing temperature. Strong crystalline orientation along the (002) c-axis crystalline plane (with intensity ratio _ (002) value up to 0.95) was exhibited for films fabricated from low precursor concentrations, multi-layered and furnace pre-heated films. Optical transmittance and electronic bandgap was measured and calculated using UV-visible spectroscopy. Thin films with high transparency (> 98 % (T) after substrate subtraction) were achieved for films prepared from low precursor concentrations, while absorption wavelength and optical bandgap energy were consistent and in good agreement with recognised values of zinc oxide. Reproducibility and reliability tests carried out on the films show high morphological consistency and stability against temperature fluctuation, moisture and electrochemical effects. Surface morphologically, the films were dense. The electrical resistivity of the (single- and multi- layer) films, before and after forming gas treatment was also measured. The minimum resistivity value of all the single-layer films was calculated to be 9.58 x 102 _cm, and the electrical resistivity showed an overall mprovement (up to one order of magnitude). On contrary, the multi-layered films, which are more resistive, worsened in resistivity after forming gas treatment.