Conductive indium-doped zinc oxide films prepared by atmospheric-pressure chemical vapour deposition

摘要

Transparent and conductive oxide films have been actively studied in recent years because of their potential applications for solid-state display devices, solar cells etc. Generally, transparent and conductive ZnO films have the following superior properties: lower cost than In2O3-SnO2 (ITO) films, lower toxicity than cadmium containing films, and greater stability in hydrogen plasma than ITO-based films [1], The reduction in the basic cost of the cells is the most important objective for solar cell applications [2]. In-doped ZnO films with low electrical resistiv-ity and high transmittance in the visible region have been prepared by various methods [3,4]. We have reported previously the preparation of Al-doped ZnO films by the same method [5]. In this study, ZnO:In films were prepared using an atmospheric pressure thermal-chemical vapour deposition (CVD) appara-tus [5, 6] with a slit nozzle. A schematic diagram of the apparatus is shown in Fig. 1 and the preparation conditions are listed in Table I. Bis(2,4-pentanedio-nato)zinc [Zn(acac)2] and tris(2,4-pentanedionato)in-dium [In(acac)3] were used as the source materials. The source compounds were vaporized and carried with nitrogen towards a slit-type nozzle (0.5 mm X 20 mm). Nitrogen carriers containing the source compounds were mixed and ejected against the substrates from the slit under atmospheric pressure. The substrates were heated on a hot plate that moved rectilinearly at a speed of 0.17 mm s"1 to make large-area samples. The thickness of the films was measured using a surface-roughness detector. The deposition rate was determined from the relationship between the film thickness and deposition time at a stationary state. X-ray diffraction (XRD) measure-ments were performed to determine the structure and crystallite size of the films. The surface morphology of the films was observed using a scanning electron microscope (SEM).