Structural characterization and phase transformations in metal oxide films synthesized by successive ionic layer deposition (SILD) method

In this paper the peculiarities of phase composition and morphology of metal oxides synthesized by successive ionic layer deposition (SILD) method are discussed. The main attention is focused on SnO2-based metal oxides, which are promising materials for gas sensor applications. FTIR spectroscopy has shown that the precipitates of metal oxides, deposited by SILD method, are hydroxide, peroxide or hydrated metal oxide-based compounds. After annealing at relatively low temperatures (200-400?C) these compounds release both water and peroxide oxygen and transform into corresponding oxides. According to XRD, SEM and AFM measurements it was confirmed that deposited films had fine-dispersed structures. Only after annealing at Tan>500?C, XRD diffraction peaks, typical for nanocrystalline material with grain size < 6-8 nm, were observed. High roughness and high degree of agglomeration are important peculiarities of metal oxides deposited by SILD. Metal oxide films consist of spherical agglomerates. Degree of agglomeration of the films and agglomerate size could be controlled. It was found that introduction of various additives in the solution for SILD could sufficiently change the microstructure of synthesized metal oxides. .