Preparation of High Quality Indium Tin Oxide Film on a Microbial Cellulose Membrane Using Radio Frequency Magnetron Sputtering

Microbial cellulose (MC) membranes produced by Acetobacter xylinum NUST4.1, were used as flexible substrates for the fabrication of transparent indium tin oxide (ITO) electrodes. Transparent and conductive ITO thin films were deposited on MC membrane at room temperature using radio frequency (RF) magnetron sputtering. The optimum ITO deposition conditions were achieved by examining crystalline structure, surface morphology and optoelectrical characteristics with X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and UV spectroscopy. The sheet resistance of the samples was measured with a four-point probe and the resistivity of the film was calculated. The results reveal that the preferred orientation of the deposited ITO crystals is strongly dependent upon with oxygen content (O2/Ar, volume ratio) in the sputtering chamber. And the ITO crystalline structure directly determines the conductivity of ITO-deposited films. High conductive [sheet resistance ∼120 Ω·square−1 (Ω·sq−1)] and transparent (above 76%) ITO thin films (240 nm thick) were obtained with a moderate sputtering power (about 60 W) and with an oxygen flow rate of 0.25 ml·min−1 (sccm) during the deposition. These results show that the ITO-MC electrodes can find their potential application in optoelectrical devices.