Nanocluster evolution in Ge+ ion implanted Ta2O5 layers

Ion implantation-induced nanoclusters were synthesized in reactive sputtered Ta2O5 films by Ge+ implantation and subsequent annealing. The effects of ion fluence and post-implantation thermal treatment on the kinetics of the nanoclustering were investigated. Ge+ ions with energy of 40 keV and fluences of 5 × 1015, 1 × 1016 and 5 × 1016 cm− 2 were implanted in the Ta2O5 layers at room temperature. The samples were thermally treated by rapid thermal annealing in vacuum at 700 °C and 1000 °C for 30, 60 and 180 s. Structural studies of all samples were done by Cross-sectional Transmission Electron Microscopy in diffraction and phase contrast mode. Under optimized conditions (high implantation fluence, subsequent annealing) nanoclusters are formed around the projected ion range of the implanted Ge+ ions. The structure of the implanted Ta2O5 matrix changes from amorphous to orthorhombic when the annealing was performed at 1000 °C. Although the Ta2O5 matrix crystallizes, no evidence is obtained for crystallization of the embedded nanoclusters even after annealing at 1000 °C.