Schematic representation of the three types of film structures of this study. (a) ultrastable film of 400 nm thickness, (b) ultrastable film of 600 nm thickness, and (c) sequence of conventional and ultrastable glass films totaling 800 nm thickness. The stacked structure of (c) consists of layers of 100, 325, 50, 275, and 50 nm and has a combined thickness of 200 nm (25%) of “conventional” material deposited at T sub = 0.99 T g and a total of 600 nm (75%) of ultrastable material deposited at T sub = 0.85 T g.
(a) Dielectric loss spectra of 600 nm ultrastable IMC films at different times when annealed at T ann = 319.0, 322.5, and 325.0 K. Loss amplitudes rise with increasing annealing time. The lines are best HN fits using the same relaxation time (τ HN) and shape parameters (α HN,γ HN) that describe the conventional IMC supercooled liquid. (b) The relaxation intensity obtained by HN fitting as a function of time for 600 nm ultrastable IMC films annealed at the same sequence of annealing temperatures. The dashed line shows the value of Δɛ for the completely transformed film, the solid lines are linear fits for Δɛ(t ann) during the transformation, and the area shaded grey indicates the estimated total time scale for the transformation.
Stars represent the transformation times, t trans, of the 600 nm ultrastable IMC films as a function of the annealing temperature as derived from the results of Fig. 2(a) . Closed and open circles reflect t trans values calculated from the SIMS studies, Ref. 26 , with the assumption of one and two growth fronts, respectively. The lines are linear fits to the SIMS results. The structural relaxation times of the conventional liquid from Ref. 42 are shown in terms of dielectric peak relaxation times, τ α, as diamonds. The arrow indicates that t trans is approximately equal to 104 τ α.
(a) Dielectric spectra of 400 nm ultrastable IMC, 600 nm ultrastable IMC, and 800 nm stacked IMC films (see Fig. 1 ) at different times during annealing at 322.5 K. (b) Time dependence of the relaxation intensity, Δɛ(t ann), for the same three films. The dashed line shows the value of Δɛ for the completely transformed film, the solid lines are linear fits for Δɛ(t ann) during the transformation, and the area shaded grey indicates the estimated total time scale for the transformation. In the lower panel, the yellow area represents the initial relaxation intensity generated from the conventional IMC layers.
Comparison of the dielectric permittivity (ɛ′) and loss (ɛ″) of a 600 nm IMC film prepared in the conventional liquid state (symbols) and a 400 nm ultrastable IMC film after complete transformation to the supercooled liquid (lines). In each panel, separate curves are for different temperatures between 315 K and 350 K as indicated. The same results are obtained for the other sample configurations shown in Figs. 1(b) and 1(c) .
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