Doped Tin Oxide Transparent Conductive Films Prepared By RF Magnetron Sputtering

Transparent conductive oxide thin （TCO）films have excellent optical and electricproperties, and plays an important and indispensable role in the electron and informationindustries, and these wide band gaps semi-conductive oxides attracted more and moreresearchers’ attention. As the wide band gap semi-conductive material, tin oxide (SnO2)shows the great application potential due to its high exciton binding energy, low electricalconductivity, high transmittance within the visible wavelength and so on. F doped SnO2(FTO) thin film, prepared by RF magnetron sputtering from powder targets, was studies inthis thesis. Magnetron sputtering technique is environmental friendly, and avoids gaseousfluorine discharged into air, as Chemical Vapor Deposition does. Also, this techniquesolves the problems caused by precursors by using Spray Pyrolysis technique. Powdersdirectly used as targets, without sintering processes, were cheap in cost, and avoid thecracking by using sintering targets.This paper includes three experiments. The firstly, target power, oxygen partial andthe separation between target and substrate were selected as the deposition parameters,and the experiments were designed according to the orthogonal experiment method tostudy the effect of the parameters on the structure and properties of the films. Secondly,the effect of oxygen partial pressure on the structure and properties of the films wasinvestigated. Thirdly, the effect of the different doping source (SnF2, SnF4) on thestructure and properties of the film was studied. The structures of the film were examinedby X-ray diffraction (XRD), Field emission transmission electron microscopy （FETEM）and Atomic force microscope (AFM). The optical properties of the film were measured byUV-vis spectrophotometer, and the electrical properties by Hall Effect MeasurementSystem.The results indicate that the crystal structure of FTO films was rutile type with (101)(without oxygen flow) or (110)(with oxygen flows) preferred orientations. The FTO filmshowed uniformly columnar grain particles. In the FTO orthogonal experiments, thetransmittance of the FTO films within visible wavelength was up to91.6%. The opticalband gaps of the film varied between3.76~3.87eV. Considering the optical and electricproperties, the suitable process parameters were selected as10cm、300W、0sccm. Oxygenflows did changed the morphological structure and the orientations of the films, andtherefore affect the optical electrical properties of the films. The main preferredorientation of the films deposited with0~1sccm was (101). With the increase of oxygenflows by2and more, the intensity of (110) was increased and became the main preferredorientation. With the increase of oxygen partial pressure, the transmittance of the filmincreased and the conductivities decreased. There was slightly difference of the properties of the tin oxide films by doping SnF4and SnF2film: the resistivity of the FTO films bydoped SnF2were slightly lower than those doped SnF4.