Physical and electrical properties of Ge-implanted SiO2 films

Metal-oxide-semiconductor structures with a Ge nanocrystal embedded in SiO2 films were fabricated by Ge+ ion implantation and subsequent high-temperat ure annealing. The Raman spectra indicate the evidence of self-assembled Ge nanocrystals in the SiO2 films. The Ge size and its density were estimated to 3-5 nm and 1x10(12)/cm(2), respectively. Photoluminescence spectra show ed a strong blue-violet band around 400 nm and a weak near-infrared band ar ound 750 nm, respectively. The several implantation-induced deficient cente rs are believed to be responsible for the blue-light luminescence. Capacita nce-voltage characteristics exhibit the flatband voltage shifts of 1.02 V a fter the electron injection into the SiO2/Ge/SiO2 potential well. An anomal ous leakage current was clearly observed in the current-voltage characteris tics. The precise simulation of quantum electron transport in the SiO2 film indicates that the anomalous conduction is originated from resonant tunnel ing in the SiO2/Ge/SiO2 double-well band structure. (C) 2001 American Insti tute of Physics.