ELECTROCHROMISM OF FLUORINATED AND ELECTRON-BOMBARDED TUNGSTEN-OXIDE FILMS

Reactive de magnetron sputtering of W was performed in a plasma of Ar + O-2 with and without CF4 addition and substrate bias. Structural stu dies by atomic force microscopy, X-ray diffraction, infrared reflectan ce spectroscopy, and Raman spectroscopy indicated that the electron e bombardment associated with a positive substrate bias led to grain gro wth and partial crystallization while maintaining a high density of W= O double bonds presumably on internal surfaces. Electrochemical measur ements showed that the durability under extended Li+ intercalation/dei ntercalation was excellent for e-bombarded oxide films and poor for ox yfluoride films. Spectrophotometric studies of the electrochromism yie lded that the color/bleach dynamics was slow for the e-bombarded oxide but fast for the oxyfluoride. The range of optical modulation was lar ge. Tandem films, with a thin protective layer of e-bombarded oxide co vering a thicker oxyfluoride layer, were able to combine rapid dynamic s with good durability. (C) 1995 American Institute of Physics.