Post annealing temperature effect on properties of Ga and F codoped ZnO thin films prepared by RF magnetron sputtering

Transparent and conducting gallium (Ga) and fluorine (F) codoped ZnO (GFZO) thin films were deposited on glass substrates by RF magnetron sputtering in CF
₄
/Ar atmosphere with a ZnO:Ga
₂
O
₃
(3 wt%) target. The influence of post-deposition annealing temperature on the structural, electrical, and optical properties of GFZO thin films was investigated. XRD results indicated that all the films were polycrystalline with a hexagonal wurtzite structure and exhibited a c-axis preferred orientation. The grain sizes of GFZO films calculated from the full-width at half-maximum of the (002) difïraction peaks increased from 17.4 to 25.0 nm when the annealing temperature rose from RT to 400 °C. The electrical conductivity and optical transmittance of the GFZO films were also enhanced by 127% and 2.4%, respectively, after a 400 °C-annealing treatment. The lowest resistivity of 3.442×10
^-3
Ω-cm, the highest average transmittance of 93.4%, and the highest energy band gap of 3.52 eV were achieved as the sample annealed at 400 °C. The variation of the resistivity after 28 days was within 3% for the 400 °C-annealed sample. The average transmittance in the visible range was over than 91% for all the samples, regardless of annealing temperature. The findings show post-deposition thermal annealing effectively improved the opto-electronic properties of the developed GFZO thin films.