Room Temperature Growth of Indium Oxide Films by Reactive Ion Beam Assisted Deposition
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1012-Y03-02
ROOM TEMPERATURE GROWTH OF INDIUM OXIDE FILMS BY REACTIVE ION BEAM ASSISTED DEPOSITION Kai Wang1, Yuriy Vygranenko1, and Arokia Nathan2 1 Electrical and Computer Engineering, University of Waterloo, Waterloo, N2L 3G1, Canada 2 London Centre for Nanotechnology, University College London, London, WC1H 1AH, United Kingdom
ABSTRACT We report the growth of indium oxide thin films at room temperature by oxygen ion beam assisted e-beam evaporation for device applications. We examined the influence of deposition conditions on film properties including the crystal structure, resistivity, optical transmittance, stoichiometry, morphology, and intrinsic stress. X-ray diffraction analysis shows that the film structure changes from amorphous to polycrystalline with preferred (222) orientation when the discharge current increases from 0.5 A to 2.0 A. It is also observed that film resistivities can be tailored over a wide range, from 3◊10-4 Ω-cm to 2◊109 Ω-cm by modifying both the evaporation rate and the discharge current. X-ray photoelectron spectroscopy data reveal that the highly-resistive films are more oxygen-enriched than the highly-conductive counterparts due to the electrical activity of oxygen vacancies. All films studied in this work show an optical transmittance up to 80%. Thus, high-performance indium oxide films can be engineered by reactive ion beam assisted deposition to meet different application requirements of devices such as solar cells, photodetectors, OLEDs, transparent TFTs, and optical coatings. INTRODUCTION Transparent conducting oxides (TCOs) have been widely used as transparent electrodes for many optoelectronic devices such as flat panel displays, solar cells, image sensors, and electrochromic devices [1]. These applications generally require films with low resistivity, high transmittance, low stress, and smooth microstructure. The most common TCOs are tin doped indium oxide (ITO), aluminum doped zinc oxide, and fluorine doped tin oxide [1] and the associated deposition techniques include sputtering, evaporation, chemical vapor deposition, and laser ablation [1]. Recently, electronics based on transparent oxide semiconductors (TOSs) has been gaining significant interests. Devices such as thin-film transistors [2-9] and diodes [10-12] have been demonstrated. However, preparation of high-quality semiconducting oxide films with controllable properties by conventional techniques such as sputtering and evaporation still remains a challenge. In this work, indium oxide films with controllable properties have been grown at room temperature by oxygen ion beam assisted e-beam evaporation. We studied the influence of deposition conditions on film properties including the crystal structure, resistivity, optical transmittance, stoichiometry, morphology and intrinsic stress.
EXPERIMENT Indium oxide films were prepared by using reactive ion beam assisted e-beam evaporation (IBAE). Figure 1 shows a schematic diagram of the IBAE system illustrating the electron beam evaporation source and the ion source m
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