Electron Transport through Thin SiO2 Films Containing Si Nanoclusters

The electron transport mechanisms through nanocomposite SiO2(Si) films containing Si nanoclusters in the dielectric SiO2 matrix have been investigated. SiO2(Si) films were obtained by oxide assisted growth. At the first stage the SiOx films with different content of excess Si were deposited by LP CVD method. The second stage includes high temperature (T=1100 degrees C) annealing of SiOx films that promotes the formation of Si nanocrystals. Current transport through SiO2(Si) films was studied in the temperature range 100-350 K. As it was observed the dominant mechanism of electron transport depends both on the voltage and temperature. The Mott's conductivity caused by traps near Fermi level was revealed in low-voltage range for all temperatures. At increasing the voltage the space-charge limited current (SCLC) conductivity is observed for films with higher content of excess silicon while in case of low content of Si the Pool-Frenkel mechanism dominates. The further increase in the voltage results in a double carrier injection.