Optical and Electrical Properties of Nitrogen Ion Implanted Fluorine Doped Tin Oxide Films

Tin oxide films were implanted with N+ at various energies between 5 to 40 keV for different ion doses between 1014 to 1016 cm-2. The microstructure, optical and electrical properties of the films were investigated. From Transmission Electron Microscopy the implanted films were shown to be amorphous. The implanted thickness for the 10 keV and 40 keV were found to be 30 nm and 110 nm, respectively. The ion penetration depths for these films were calculated using SRIM-2000 and found to be 35 nm (at 10 keV) and 120 nm (at 40 keV). The optical properties of the implanted films were measured and transmittance was found to decrease with increasing implantation energy and/or ion dose. The luminous transmittance of the films decreased from 0.70 for the unimplanted film to about 0.57 for the highest implantation energy and largest ion dose. By annealing the films large part of the defects have been removed and thereby increasing the transmittance of the films. The electrical properties of the films were investigated and found an increase of sheet resistance with increasing implantation energy and/or ion dose. The increase of sheet resistance after ion implantation is caused by a loss of crystallinity of the tin oxide films. After annealing the sheet resistance decreases because the crystallinity was partially recovered.