Atmospheric Pressure Chemical Vapour Deposition of Fluorine-doped Tin(IV) Oxide from Fluoroalkyltin Precursors

Perfluoroalkytin compounds R(4-n)Sn(Rf)n (R = Me, Et, Bu, Rf = C4F9, n = 1; R = Bu, Rf = C4F9, n = 2, 3; R = Bu, Rf = C6F13, n = 1) have been synthesised, characterised by 1H, 13C, 19F and 119Sn NMR and evaluated a precursors for the atmospheric pressure CVD (APCVD) of F-doped SnO2 thin films. All precursors were sufficiently volatile at in the range 84 – 136oC and glass substrate temperatures of ca. 550oC to yield high quality films with ca. 0.79 – 2.02% fluorine incorporation, save for Bu3SnC6F13 which incorporated < 0.05% fluorine. Films were characterised by XRD, SEM, thickness, haze, emissivity, sheet resistance. The fastest growth rates and highest quality films were obtained from Et3SnC4F9. An electron diffraction study of Me3SnC4F9 revealed four conformations of which only the two of lowest abundance showed close F…Sn contacts which could plausibly be associated with halogen transfer to tin and in each case it was fluorine attached to either the γ- or δ-carbon atoms of the Rf chain