Electrical And Optical Properties Of Non Stoichiometric Tin Oxide Films

This dissertation, "Preparation and Post-annealing Effects on the Optical Properties of Indium Tin Oxide Thin Films" by Rongxin, Wang, 王榮新, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled PREPARATION AND POST-ANNEALING EFFECTS ON THE OPTICAL PROPERTIES OF INDIUM TIN OXIDE THIN FILMS Submitted by WANG Rong Xin for the degree of Doctor of Philosophy at The University of Hong Kong in April 2005 Many opto-electronic devices, such as III-V compound devices, liquid crystal displays, solar cells, organic and inorganic light emitting devices, and ultraviolet photodetectors, demand transparent electrode materials simultaneously having high electrical conductance. To meet the requirements for particular applications, a great deal of basic research and studies have been carried out on the electrical and optical properties of these materials. As a most promising candidate for such materials, indium tin oxide (ITO) has attracted interest in recent years. Furthermore, ITO has many unique properties such as excellent adhesion on the substrate, thermal stability and ease of patterning. The deposition of high-quality ITO thin films is a key step for successful application of ITO thin films as transparent electrode materials. To obtain optimal electrical and optical properties of ITO films, the growth parameters and conditions must be determined. Moreover, the optical and electrical properties of ITO contact layers, which can either be on the top side or the bottom side of a device, are influenced by various post-deposition treatments. For the present work, ITO thin films were deposited on glass and quartz substrates using e-beam evaporation with different deposition rates. The influence of substrate material, deposition rate, deposition gas environment and post-deposition annealing on the optical properties of the films was investigated in detail. Atomic force microscopy, X-ray diffraction and X-ray photoemission spectroscopy was employed to obtain information on the chemical state and crystallization of the films. Analysis of these data suggests that the substrate material, deposition rate, deposition gas environment and post-deposition annealing conditions strongly affect the chemical composition and the microstructure of the ITO films and these in turn influence the optical properties of the film. Oxygen incorporation transfers the In O phase to the In O phase and removes metallic In to form both indium oxide 2 3-x 2 3 phases. Both of these reactions are beneficial for the optical transmittance of ITO thin films. Moreover, it was found that the incorporation and decomposition reactions of oxygen can be controlled so as to change the optical properties of the ITO thin films reversibly. DOI: 10.5353/th_b3154617 Subjects: Thin films - Optical properties Indium compounds Annealing of metals

In this paper, we investigated whether the optical and electrical properties of indium tin oxide (ITO) films are degraded under laser irradiation below their laser ablation threshold. While performing multi-pulse laser damage experiments on a single ITO film (4.7 ns, 1064 nm, 10 Hz), we examined the optical and electrical properties in situ. A decrease in reflectance was observed prior to laser damage initiation. However, under sub-damage threshold irradiation, conductivity and reflectance of the film were maintained without measurable degradation. This indicates that ITO films in optoelectronic devices may be operated below their lifetime laser damage threshold without noticeable performance degradation.