Glass surface roughness with defined morphologies is realized by a two step lithography-free process: first sputter deposition
of an around 10 nm thin unstructured metallic layer onto the surface, second reactive ion etching in an Ar/CF4 high
density plasma. During the etch step metal atoms and etch gas constituents build hardly volatile metal halogen compounds
resulting in self-masking of the glass. Several metals like Ag, Al, Au, Cu, In, and Ni can be employed as the
metallic seed layer in this technology. Within the second process step the sacrificial metal layer is completely removed
from the surface. Due to the locally varying etch velocity further etching causes formation of pits and elevations with
typical height and lateral dimensions on the order of 0.5 μm. Surface morphology is influenced by choice of seed layer
material and etch parameters, resulting in a multitude of different morphologies. Hence optical scattering characteristics
of the glass can be tuned almost arbitrarily over a wide range. The dosed extents of light scattering could possibly be
used advantageously for specific classes of applications, e.g. lighting engineering, efficiency enhancement of thin film
solar cells or organic light emitting diodes.
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