Uniform fabrication of Ge nanocrystals embedded into SiO₂ film via neutron transmutation doping

Nanocrystalline ⁷⁴Ge embedded SiO₂ films were prepared by employing ion implantation and neutron transmutation doping methods. Transmission electron microscopy, energy dispersive x-ray spectroscopy, and photoluminescence of the obtained samples were measured. The existence of As dopants transmuted from ⁷⁴Ge is significant to guarantee the uniformity and higher volume density of Ge nanocrystals by tuning the system's crystallinity and activating mass transfer process. It was observed that the photoluminescence intensity of Ge nanocrystals increased first then decreased with the increase of arsenic concentration. The optimized fluence of neutron transmutation doping was found to be 5.5×10¹⁷cm^-2 to achieve maximum photoluminescence emission in Ge embedded SiO₂ film. This work opens a route in the three-dimensional nanofabrication of uniform Ge nanocrystals.