ON THE PATHWAYS OF AEROSOL FORMATION BY THERMAL-DECOMPOSITION OF SILANE

The mechanism bf aerosol formation during thermal decomposition of sil ane is investigated. To this end a Simultaneous analysis of gas-phase products of silane decomposition (disilane, trisilane, hydrogen) and t he parameters of the forming aerosol particles of amorphous hydrogenat ed silicon is carried out. The silane loss and gaseous product concent rations are analyzed by mass-spectrometer; particle size and morpholog y are analyzed by transmission electron microscope. The total amount o f bonded hydrogen and the relative amounts of monohydride and polyhydr ide groups contained in the particles are analyzed by the methods of h ydrogen evolution and IR-spectroscopy. It is concluded that during the initial stages of aerosol formation, particles are mainly formed from gaseous products with a stoichiometry SinH2n. At these stages the hyd rogen in particles is mainly contained as a constituent of polyhydride groups. During later stages the particles are formed from hydrogen-de pleted intermediates, and the hydrogen in particles is mainly bound in monohydride groups. Copyright (C) 1997 Elsevier Science Ltd