Electrical and emission properties of nano-composite SiOx and SiO2(Si) films

The electrical and emission properties of as deposited and annealed SiO_x films have been investigated in details. The films with thickness 20-100 nm are obtained by thermal evaporation of silicon powder in vacuum (2-3)×10^-5 Torr and plasma enhanced chemical vapor deposition (PECVD) methods at room temperature on Si substrate. Using atomic force microscopy, it is shown that as deposited SiO_x (x=3) film is a nano-composite one in which the Si cluster is coated with SiO phase. At low electric fields, the I-V characteristics of dark current of the initial SiO_x films correspond to Fenkel-Poole transport mechanism. The Fowler-Nordheim tunneling dominates at higher electric fields. As to annealed SiO₂(Si) films, the modified Fowler-Nordheim electron tunneling through trapezoidal SiO₂ barrier between silicon nanoclusters restricts the current flow. The analysis of current-voltage characteristics and composition of the SiO₂(Si) film allowed to estimate the Si clusters size. The obtained results are in good agreement with AFM data. The effective electron field emission from flat silicon wafer coated with nanocomposite SiO_x film is also observed. Results of the electron field emission measurement show that initial sample emission current (10^-7-10^-6 A) is observed at high voltages (570-770 V). Field emission from thermally treated samples is not observed in the whole range of the applied voltages.