Abstract
We explore the size and spatial microheterogeneity of contact
pin-printed spots formed on porous silicon (pSi). Glycerol was contact
printed at room temperature onto as-prepared, hydrogen-passivated pSi
(ap-pSi) using 50 or 200 µm diameter solid pins. The pSi was then
subjected to a strong oxidizing environment (gaseous O3) and
washed to remove the glycerol masks. The glycerol-free regions were
converted to oxidized pSi (ox-pSi); the glycerol-coated regions were
protected from O3, but not entirely. The final array is
described as circularly shaped “ap-pSi” regions on a field of ox-pSi. When
comparing the areas outside and inside the glycerol-masked pSi spots, one
finds dramatic differences in the Si–O–Si, SiHx (x = 1–3) and OySiHx (y, x
= 1–3) levels with a spatially dependent continuum of compositions across
the spot diameter. Experimental conditions could be adjusted to tune the
final ap-pSi spot diameter and edge widths from 90 µm to 520 µm and 20 µm
to 130 µm, respectively. The resulting ap-pSi spot diameter is explained
by using molecular kinetic theory and time-dependent glycerol imbibement
into the pSi within a one-dimensional Darcy’s law model.
© 2016 The Author(s)
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