Influence of the substrate temperature on the initial stages of growth of barium strontium titanate films on sapphire

Abstract

The initial stages of growth of ferroelectric films of barium strontium titanate BaSrTiO 3 on singlecrystal sapphire substrates have been experimentally investigated as a function of the deposition temperature. It has been shown that, at the initial stage of the condensation of the BaSrTiO 3 film on sapphire, the temperature of the substrate determines the mechanisms of mass transfer of deposited atoms and the processes of nucleation.

SrTiO3 Thin Films on Dielectric Substrates for Microwave Applications

“…The spectra of films deposited at different substrate temperatures did not differ significantly in shape, which indicated a single mechanism for the nucleation of strontium titanate films on an alumina in the deposition temperature range investigated [39]. As an example, Figure 1 shows experimental and simulated spectra of He + ions after interaction with island films grown at temperatures of 800 • C and 900 • C. The parts of the spectra corresponding to the scattering of ions on strontium and titanium are triangular peaks with a prolonged low-energy front.…”

Enhanced Tunable Properties of Strontium Barium Niobate Films on Dielectric Alumina Substrate at Microwaves

“…The spectra obtained from films deposited at different substrate temperatures do not have significant differences, which indicates a similar form of the SBN islands on the substrate surface and, therefore, indicates similar mechanisms of their nucleation. The sections of the spectra corresponding to the scattering of helium ions on Ba, Sr, and Nb have a triangular shape, which corresponds to the pyramidal shape of the islands [41]. Data on the technological conditions and on the structure of the island SBN films are given in Table 1.…”

“…In addition, during film growth on alumina, substrate defects significantly increase the rate of nucleation, reducing the height of the activation barrier, which leads to rapid filling of the substrate with islands of low height [44]. This mechanism of growth of FE films occurs, as a rule, on polycrystalline substrates that are not structure-forming for the growing film, which subsequently leads to the formation of a polycrystalline layer [41,45]. The MEIS analysis data show that the thickness of the SBN island films deposited at temperatures 750-950 °C ranges from 1.3 to 2.16 nm, the degree of substrate area covered by islands ranges from 23% to 42%, and both parameters do not correlate with the change in substrate temperature.…”

“…In addition, during film growth on alumina, substrate defects significantly increase the rate of nucleation, reducing the height of the activation barrier, which leads to rapid filling of the substrate with islands of low height [44]. This mechanism of growth of FE films occurs, as a rule, on polycrystalline substrates that are not structure-forming for the growing film, which subsequently leads to the formation of a polycrystalline layer [41,45].…”