Nanocluster evolution in Ge~+ ion implanted Ta_2O_5 layers

摘要

Ion implantation-induced nanoclusters were synthesized in reactive sputtered Ta_2O_5 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 x 10~(15), 1 x 10~(16) and 5 x 10~(16) cm~(-2) were implanted in the Ta_2O_5 layers at room temperature. The samples were thermally treated by rapid thermal annealing in vacuum at 700℃ and 1000℃ 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 Ta_2O_5 matrix changes from amorphous to orthorhombic when the annealing was performed at 1000℃. Although the Ta_2O_5 matrix crystallizes, no evidence is obtained for crystallization of the embedded nanoclusters even after annealing at 1000℃.