am9b07308_si_001.pdf (2.23 MB)
Nanopattern-Embedded Micropillar Structures for Security Identification
journal contribution
posted on 2019-08-08, 16:36 authored by Zhi-Jun Zhao, SoonHyoung Hwang, Moonjeong Bok, Hyeokjung Kang, Sohee Jeon, Sang-Hu Park, Jun-Ho JeongA novel method was
developed for fabricating nanopatterns embedded
on micropillar-structured surfaces using nanowelding technology for
security identification. Commonly used substrates, that is, polyethylene
films, glass wafers, Si wafers, and curved surfaces, were employed
and their characteristics were evaluated. Cr was deposited onto the
selected substrate to strengthen the adhesion force, and an adhesive
layer of ultra-thin metal was deposited on top of the Cr layer. Lastly,
nanopatterns were embedded on the substrates by nanowelding. The morphologies,
cross sections, and three-dimensional (3D) images of the fabricated
nanostructures were evaluated, and their crystalline structures and
compositions were analyzed. Using the same method, nanopatterns embedded
on micropillar-structured surfaces were fabricated for the first time
as security patterns to improve security identification. The fabricated
security patterns were characterized in three stages. First, micropillar
structures and structural color were simply observed via optical microscopy
to achieve a preliminary judgment. The appearance of structural color
was due to the nanostructures fabricated on the micropillar surface.
Next, the designed nanopatterns on the micropillar-structured surfaces
were observed by scanning electron microscopy. Lastly, the changes
in the spectral peaks were precisely observed using a spectrometer
to achieve an enhanced security pattern. The fabricated security patterns
can be suitable for valuable products, such as branded wines, watches,
and bags. In addition, the proposed method offers a simple approach
for transferring metal nanopatterns to common substrates. Moreover,
the fabricated security patterns can have potential applications in
semiconductor electrodes, transparent electrodes, and security identification
codes.