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Supplementary Material
Conducted growth of SrRuO3 nanodot arrays on self-ordered
La0.18Sr0.82Al0.59Ta0.41O3(001) surfaces
R. Bachelet,a) C. Ocal, L. Garzón, J. Fontcuberta, and F. Sánchezb)
Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB,
08193 Bellaterra, Spain
a) E-mail: [email protected]
b) E-mail: [email protected]
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Supplementary Material
When the diffusion length matches the terrace width, AO-BO2 nanostripes are formed at
the surfaces of perovskite ABO3(001) single-crystals by surface diffusion with a good
lateral ordering directed by the periodic surface steps (Figs. 1c, 2b, 3a, S1). In the
explored perovskite La0.18Sr0.82Al0.59Ta0.41O3 (LSAT) single-crystals, lateral sizes of
single-terminated terraces range from 400 nm down to 80 nm, corresponding to miscut
angles from 0.03º to 0.14º, respectively. The lower-miscut substrates will then need
more time at high temperature (or annealing with enhanced temperature) to surface
patterns similar to those of higher-miscut substrates.
In Figure S2, we show that for a low miscut substrate (0.03º) complete assembly takes
more time than 2h. The surface of Figure S2a has not suffered enough annealing for a
well-defined assembly completion. After 12h, chemical terminations are assembled
(quite clear phase image) but there are still some (vacancy) islands and numerous kinks
at edges in the minority phase (Fig. S2b), that means that the surface can reach an even
more favorable morphological state. After longer treatment we expect that stripes
straighten along the steps as it has been observed previously, and after much longer
treatment (Fig. S2c), stripes tend to minimize costly step-edges and then minority-phase
areas organize from stripes to closed rounded areas as it can be observed in Fig. S2c.
We measured the AO/BO2 termination ratio on the atomic force microscopy (AFM)
phase-lag images of Fig. S2b and Fig. S2c by using the flooding tool of the WSxM
software [a]. On both images the termination ratio is roughly the same (30%)
evidencing that the surface is not degraded during annealing and that the diffusion
occurs mainly at the surface and not in volume avoiding enrichment of the surface by
bulk elements (see extreme right panels of Fig. S2b and Fig. S2c, where red pixels
represent 30% of the total area).
[a] The WSxM free software can be found at http://www.nanotec.es/; I. Horcas, R.
Fernández, J. M. Gómez-Rodriguez, J. Colchero, J. Gómez-Herrero, and A. M. Baro,
Rev. Sci. Instr. 78, 013705 (2007)
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Supplementary Material
Figure S1
(a)
(b)
Z (Å)
4
2
0
0
(c)
50 100 150
X (nm)
(d)
Figure S1. Friction force microscopy (FFM) images of a LSAT(001) (0.1º-miscut)
single-crystal after thermal treatment at 1300ºC for 6h. (a) topography, (b)
corresponding height profile, (c) friction forward and (d) friction backward. The ½ uc
steps separating the alternated AO and BO2 terraces of LSAT, imaged here by a friction
contrast, attests of the ordered separation at the nanoscale of the chemical terminations,
with correct topography, as measured in dynamic mode AFM in figure 1.
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Supplementary Material
Figure S2
(a)
(b)
(c)
Figure S2. (5×5 μm2) AFM topographic images (left panel) along with the
corresponding phase-shift images (central panel) after treatment in air of a LSAT(001)
(0.03º-miscut) single-crystal at 1300ºC for (a) 2h, (b) 12h, and (c) 72h. The same wafer
was cut in three pieces and each piece suffered one of the single-treatments. Even at these
annealing conditions, neither degradation of the atomically-flat surface, nor apparent
change in the (AO/BO2) chemical-termination ratio occurs. The right images in (b,c)
represent the corresponding phase images after flooding analysis using the WSxM
software [a] giving a termination ratio of 30% for both.
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Supplementary Material