The effects of postdeposition annealing conditions on structure and created defects in Zn_(0.90)Co_(0.10)O thin films deposited on Si(100) substrate

摘要

We analyze the effect of postdeposition annealing conditions on both the structure and the created defects in Zn_(0.90)Co_(0.10)O thin films, which deposited on the Si(100) substrates by the radio frequency magnetron sputtering technique using a homemade target. The dependence of the number and distribution of defects in homogeneously substituted Co~(+2) for Zn~(+2) ions in ZnO lattice on the annealing conditions is investigated. Orientations of thin films are in the [0002] direction with a surface roughness changing from 67 ± 2 nm to 25.8 ± 0.6 nm by annealing. The Co~(+2) ion substitution, changing from 7.5% ± 0.3% to 8.8 ± 0.3%, leads to the formation of Zn-O-Co bonds instead of Zn-O-Zn bonds and splitting of the Co 2p energy level to Co 2p_(1/2) and Co 2p_(3/2) with an energy difference of 15.67 ± 0.06 eV. The defects in the lattice are revealed from the correlations between Zn-O-Co bonds and intensity of the Raman peak at around 691 cm~(-1). In addition, the asymmetry changes of O 1s peak positions in the x-ray photoelectron spectra are in agreement with the Raman results.