PREPARATION AND CHARACTERIZATION OF F-DOPED SnO₂ NANO-THIN FILMS DEPOSITED ON PET SUBSTRATES

Abstract

Tin oxide doped with fluorine ( SnO 2 : F ) thin films were deposited on polyethylene terephthalate (PET) foils by RF reaction cosputtering at low temperature in different oxygen partial pressures. X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) were used to study the effects of the processing parameters on the crystallization and surface topography of the as-prepared SnO 2 films. The results showed that high quality SnO 2 : F thin films could be obtained by optimizing deposition conditions without intentional annealing, i.e. oxygen partial pressure to total pressure of higher than 50%, RF power higher than 50 W. The optical transmittance measurements revealed that the SnO 2 : F films were highly transparent in the visible region (90%) and showed an absorption edge redshift with increasing oxygen partial pressure from 1/4 to 3/4. The optical bandgap energy was calculated to be about 3.6 eV. Hall effect measurements confirmed that the as-prepared SnO 2 thin films possessed good electrical properties with a low resistivity of 10 -3 Ω · cm, a high carrier concentration of 9.6 × 10 18 cm -3 , and a Hall mobility of about 200 cm 2 /V · s.