Percolation in implanted Si film

The conductivity degradation of implanted Si film has been characterized by nuclear-deposited energy independently of implant conditions. The conductivity decreases as a result of the carrier density change for the nuclear-deposited energy E_n ≤ 1 × 10²³ eV/cm³, and becomes zero with mobility for E_n = 2.5 × 10²⁴ eV/cm³. These results have been investigated by the percolation theory with the assistance of the Kinchin-Pease theory. The decrease in carrier density is a result of carrier trapping by vacancy-related defects. The mobility becomes zero when the nondamaged Si cluster is localized by a heavy implantation. The calculation using the site percolation is in good agreement with the experiments, where 0.428 is assumed as the percolation threshold, and 2 as the conductivity exponent. The Si displacement energy obtained is 25 eV by comparing the theory with the experiments. The experimental results suggest that microscopically conductive domains exist even in films that are macroscopically insulating.