Homebuilt reactor design and atomic layer deposition of metal oxide thin films

Abstract: This research thesis covers work done on building an atomic layer deposition (ALD) reactor followed by the development and optimization of an ALD process for indium oxide thin films on crystalline silicon substrates from new precursors using this new homebuilt cost-effective tool. This work describes the design, building and testing of the ALD system using an indium triazenide precursor and water in a novel precursor combination. The reactor was built to be capable of depositing films with comparable results to commercially built systems.Indium oxide thin films were deposited as the deposition temperature was varied from 154 to 517 0C to study the effects of deposition temperature on the obtained film thicknesses and ascertain the ALD temperature window between 269-384 0C. The presence of indium oxide films was confirmed with X-ray diffraction analysis, which was also used to study their crystallinity. The films were found to have a polycrystalline structure with a cubic phase. Measurement of film thickness was performed using X-ray reflectivity which determined a growth rate of approximately 1 Å/cycle. Elemental composition was determined by X-ray photoelectron spectroscopy which confirmed contamination-free indium rich films. Scanning electron microscope imaging was used to examine the surface morphology of the films as well as thick cross-sectional thicknesses.Since indium oxide films are potentially useful in various electronic, optical, and catalytic applications, emphasis is also placed on the accurate characterization of the chemical and physical properties of the obtained thin films. Optical and electrical properties of the produced transparent conducting oxide films were measured for transparency (and optical band gap) and electrical characterization by resistivity measurements, from UV-Vis spectrophotometry and 4-point probe data respectively. A high optical transmission >70 %, a wide band gap 3.99-4.24 eV, and low resistivity values ∼0.2 mΩcm, showed that In2O3 films have interesting properties for various applications confirming indium oxide a key material in transparent electronics.