Ge nanocrystals in SiO2 films

SiO 2 /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 °C and 1000 °C. Secondary ion mass spectrometry results indicate that the Ge precipitates into the bulk SiO2 at a density of 1×1012 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 (VFB) shifts to 0.91 V after the electron injection. The VFB shift is attributed to the charge storing for a single electron per potential well.