Effects of annealing on optical properties of Zn-implanted ZnO thin films

Zn-ion-implantation to a dose of 1 × 10 17 ions/cm 2 was performed on ZnO thin films deposited on fused silica glass substrates by the sol–gel technique. After ion implantation, Zn-implanted ZnO films were annealed in air at different temperatures from 500 to 900 °C. The effects of ion implantation and post-thermal annealing on the structural and optical properties of the ZnO films were investigated by X-ray diffraction (XRD), photoluminescence (PL) and optical absorption measurements. XRD reveals that diffraction peaks recover at ∼700 °C. Optical absorption measurements show that the absorption edge blueshifts when the annealing temperature is below 600 °C while redshifts when the annealing temperature exceeds 600 °C. Urbach energy decreases with increasing the annealing temperature from 500 to 600 °C while increases from 600 to 900 °C. PL results showed that both near band edge (NBE) excitonic UV emission and defect related deep level emission (DLE) increased with increasing annealing temperatures from 500 to 900 °C.