Comparison between the GIXR experimental (black dots) and fitting curves for the Al(1%wtSi)/Zr (No. 3) and Al(Pure)/Zr (No. 10 in Table I ).
Surface roughness as a function of the thicknesses of Al layers for two Al/Zr (Al(1%wtSi)/Zr and Al(Pure)/Zr) systems.
XRD measurements relative intensity vs 2θ angle for Al(1%wtSi)/Zr (a) and Al(Pure)/Zr (b) multilayers. The samples with variable thickness of Al layers are in different colors.
Changing trends of 2θ (a) and crystal size (b) with increasing Al layer thicknesses for the two Al/Zr systems.
Cross-sectional TEM images of Al(1%wtSi)/Zr multilayer samples in bright field (a), (d), Fourier-filtering corresponding to (a) and (d) images (b) and (e), and SAED patterns (e), (f) for the samples of Al(1%wtSi)/Zr (Al = 1.6 nm, (a)–(c)) and Al(1%wtSi)/Zr (Al = 1.7 nm, (d)–(f)).
A few simplified pictures of the amorphous-to-crystalline transition in Al layers. (a) Below the critical thickness, the Al layer is entirely amorphous, and the Zr-on-Al interlayer is wider than the Al-on-Zr one. (b) As the Al layer grows within the transition but does not exceed the critical thickness, just a few isolated nucleation points appear, especially for the Al(1%wtSi)/Zr systems. The Zr-on-Al interlayer is still the thickest one. (c) When the thickness of Al layer just at the critical thickness, Al crystallites nucleate in most points of the layer, which increases the interfacial and surface roughness. (d) Above the critical thickness the Al layer is mostly polycrystalline, there is less roughness and the interlayers are symmetrical.
Thicknesses of Al and Zr layers in Al(1%wtSi)/Zr and Al(Pure)/Zr multilayers with different periods as derived from the GIXR simulation. The structures in the table are presented in one period.
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