Ge nanocrystals in SiO2 films

SiO2/Ge nanocrystal/SiO2 structures have been fabricated by deposition of Ge film on a SiO2 layer and subsequent oxidation of the structure at a temperature between 800 degrees C and 1000 degrees C. Secondary ion mass spectrometry results indicate that the Ge precipitates into the bulk SiO2 at a density of 1x10(12) cm(-2). Raman spectra show a sharp peak at 300 cm(-1) for the nanocrystallized Ge. The nanocrystal diameter is determined to be 5 nm on average. In the metal-insulator-silicon structure, electron storage occurs in the SiO2/Ge/SiO2 potential well via electron tunneling into the oxide film. Capacitance-voltage measurements indicate that flatband voltage (V-FB) shifts to 0.91 V after the electron injection. The V-FB Shift is attributed to the charge storing for a single electron per potential well. (C) 1997 American Institute of Physics.