Maidanchuk I. Kinetics of nanocomposite Si-SiOx films formation and their light-emitting properties

The dissertation is devoted to elucidation of thermostimulated phase separation process in thin SiOx films and developments of methods that allow controlling PL properties of the nc-Si-SiOx films. IR-spectroscopy and photoluminescent techniques were used to study processes of changes in composition of oxide phase in SiOx film and separation of Si phase during thermal annealing in time intervals 1 sec -20 min and temperatures 300-100 С. At first time it was observed kinetics of phase separation (growth of silicon phase amount with growth of annealing time). The value of diffusion coefficient was evaluated in the terms of diffusion-control model of Si nanoparticles formation. It is assumed that mobility of oxygen is in the base of structural-phase transformations mechanism in SiOx layers and formation of Si nanoparticles during annealing. Effect of hydrogen radiofrequency plasma and chemical treatment on photoluminescence spectra of SiOx layers containing Si nanoparticle s are investigated. ConsiderablePL intensity growth in the samples containing Si nanocrystals (nc-Si-SiOx) after plasma treatment is observed. Chemical treatment in ammonia and acetone vapour before thermal annealing of SiOx layers leads to the considerable changes in PL spectra effecting as on the band shape as on intensity. A new intensive PL band (with peak position near 600 nm) appears in samples treated in ammonia and acetone. It is assumed that chemical treatment leads to modification of nc-Si-SiOx interface with nitrogen or carbon atoms. It is shown that chemical and RF plasma treatment allow to increase PL intensity in nc-Si-SiOx structures and to control spectral structure in range from 560 to 950 nm.