Effect of aging time on the electrical properties of Ta + F doped ZnO films

In the present work, the effect of aging of the starting solution on the transparent conducting properties of Ta + F doped ZnO films was investigated. The films were deposited using a homemade automated jet-nebulizer spray pyrolysis technique. The doping level of tantalum is kept at 1 at% and fluorine is maintained at 10 at%. The prepared precursor solution was aged from 24 h to 120 h in steps of 24 h prior to deposition. The electrical resistivity of the films decreased with increasing aging time up to 72 h and increased upon further aging. The observed reduction in resistivity is attributed to the enhanced effective incorporation of dopant ions into the ZnO lattice, possibly facilitated by the formation of favorable chemical complexes in the aged precursor solution. Structural, morphological and optical studies carried out using XRD, FESEM with EDS, AFM and PL analyses were correlated with the results of the electrical study to support the obtained results. The film deposited using the precursor solution aged for 72 h exhibited the lowest resistivity of 1.08 × 10 −3 Ω cm along with the highest quality factor of 2.16 × 10 −4 (Ω/sq) −1 . The present study demonstrates that controlled precursor aging plays a crucial role in tailoring the optoelectronic performance of Ta + F doped ZnO films for transparent conducting oxide applications.