Transformation of SiOx films into nanocomposite SiO₂(Si) films under thermal and laser annealing

Oxide-assisted growth of Si nanocrystals includes deposition of a siliconenriched SiOx film at the first stage and annealing at the second one. The ion-plasma sputtering method has been used for deposition of the SiOx film. The influence of thermal and laser annealing on SiOx film properties has been investigated. Formation of silicon nanoislands on oxide film surface has been observed by AFM both after thermal and laser annealing. The height and surface density of the nanoislands depends both on the silicon content in the initial SiOx film and temperature of thermal annealing. The higher annealing temperature causes formation of large nanoislands, but their surface density decreases. Comparison of nanoislands created at thermal and laser annealing shows that in case of laser annealing the nanoislands are higher and their surface density is lower. The intensity of laser irradiation influences on nanoisland parameters significantly. The growth of electrical conductivity with thermal annealing temperature has been observed. The influence of gas atmosphere during annealing is also significant in case of higher temperatures. In case of laser annealing at the beginning at low laser irradiation intensities, the SiOx film conductivity increases, but the following growth of intensity causes the decrease in electrical conductivity

Nanostructuring the SiOx layers by using laser-induced self-organization

The processes of laser-induced transformation of SiOx oxide layers into the nanocomposite ones were studied. The possibility of phase separation in the form of Si nanocrystals surrounded by corresponding SiO2 oxide matrix under irradiation by nanosecond pulses of YAG:Nd+3-laser were shown. Laser radiation at the fundamental wavelength, λ1 = 1064 nm, and second harmonic, λ2 = 532 nm, were applied at researches. The size and surface concentration of nanofragments dependences on the intensity and wavelength of the laser irradiation have been determined from experimental data based on atomic force microscopy, infrared transmission spectra and electro-physical measurements. SiOx nanocomposite layers containing Si nanoparticles, the size of which depends on laser beam intensity and wavelength, have been obtained. The processes of nanoparticles formation occur mainly through generation and mass transfer of interstitial atoms in the solid mode (before the melting point threshold) due to the effect of laser thermal shock

Electron transport through nanocomposite SiO₂(Si) films containing Si nanocrystals

The current transport through insulating SiO₂ films with silicon nanocrystals in Si/SiO₂(Si)/Al structures has been investigated in the wide range of temperatures (82…350 K). The nanocomposite SiO₂(Si) films containing the silicon nanoclusters embedded into insulating SiO₂ matrix have been obtained by ion-plasma sputtering of silicon target and subsequent high-temperature annealing. Based on the detailed analysis of current-voltage characteristics, calculation of some electrical parameters has been performed and the mechanism of electron conductivity of nanocomposite SiO₂(Si) films has been ascertained. The electrical conductivity of the films is based on the mechanism of hopping conductivity with variable-range hopping through the traps near the Fermi level