Organized two-dimensional Ti–SiO2 metal quantum dot composites induced by subplantation.

Two-dimensional (2D) titanium nanodots were formed in the subsurface layer of single crystal SiO 2, i.e., a 2D Ti metal quantum dot composite, by subplantation of 9 kev Ti+ ions. Transmission electron microscopy images show that the Ti nanodots have a uniform size distribution of∼ 2 nm with very little deviation, almost constant edge-to-edge spacing (∼ 1 nm) between neighboring nanodots in the lateral direction, and a very narrow depth distribution. These nanodots exhibit no crystallinity and are smaller than our previously reported single crystalline Ti nanodots with body-centered-cubicβ phase, indicating that the size and crystallinity of metal nanodots can be controlled through subplantation. A preliminary mechanism for the formation of 2D nanodots during subplantation is discussed. [ABSTRACT FROM AUTHOR]