Ti–Sn alloy nanodot composites embedded in single-crystal SiO2 by low energy dynamic coimplantation.

Organized extremely small Ti–Sn alloy nanodots have been formed in the subsurface of SiO₂ by dynamic coimplantation of isotopic ⁴⁸Ti⁺ and ¹²⁰Sn⁺ at a low kinetic energy of 9 keV into (0001) Z-cut quartz at different substrate temperatures. Transmission electron microscopy images show that the Ti–Sn alloy nanodots are single crystal and have been formed uniformly at room temperature. They are distributed in a two-dimensional array with similar size of ∼4 nm and constant interdot spacing between each dot. The regions beyond and below the two-dimensional array are depleted of detectable nanodots. At high temperature, the distribution and crystallinity were destroyed with much smaller amorphous nanodots in a slightly deeper region. The implantation was carried out by dynamic coimplantation, rather than the commonly used sequential implantation. These results indicate that dynamic low energy coimplantation is capable of forming well-ordered two-dimensional array of alloy nanodots. [ABSTRACT FROM AUTHOR]