RADIOFREQUENCY REACTIVELY SPUTTERED VOX THIN-FILMS DEPOSITED AT DIFFERENT OXYGEN FLOWS

The effect of different oxygen flow rate on the properties of vanadium oxide thin films formed by radio-frequency, reactive sputtering depos ition are investigated. The stoichiometry of the as-deposited films wa s investigated by Rutherford backscattering spectrometry. For high oxy gen flows films were mainly V2O5, while a lower oxide was obtained at the lowest flow. Forward recoil spectrometry indicated a significant h ydrogen content in the thin films. X-ray diffraction showed that the f ilms were amorphous. The electrochromism shown by such films upon lith ium intercalation was also studied. Samples deposited at high oxygen f low were transparent/yellow, and showed a somewhat complicated electro chromic behavior. Upon lithium insertion up to 25 mC/cm(2), the films acted as cathodically coloring materials at wavelengths higher than 50 0 nm and as anodically coloring material at lower wavelengths. For the higher insertion levels, the opposite behavior was observed. Samples deposited at very low O-2, flows showed no electrochromic behavior.