In this paper, we fabricated gold particle array substrate by thermal dewetting technique. The fabrication process is
simple, reliable, cost efficient with comparing to other techniques. From optical characteristic it shows light trapping
ability to reduce reflectance around 75%. Combining light trapping and its localized plasmonic properties, this substrate
has significant advantages on plasmonic based sensing methods such as surface enhanced Raman scattering (SERS).
SERS measurement has been performed and the enhancement factor is 2.58×105. Further more, after silver thin film
deposition the enhancement can be increased up to 2 orders and the enhancement factor is 3.66×107.
KEYWORDS: Etching, Silicon, Nanolithography, Nanostructures, Reflection, Aluminum, Photomasks, Deep reactive ion etching, Reactive ion etching, Scanning electron microscopy
We have fabricated nanotextured Si substrates that exhibit controllable optical reflection intensities and colors. Si
Nanopore, which has photon-trapping nanostructure but has abrupt changes in the index of refraction displaying a
darkened specular reflection. Aluminum is evaporated on the surface of N-type Si by e-beam evaporation. Nanopore
structure is formed by a two-step AAO formation in oxalyic acid. Diameter size from 30 to 80 nm is achieved,
depending on the condition of anodization and etch. Deep reactive ionic etch (DRIE) is done, with AAO as the mask
layer. The nanopore AAO template allows etching depth of up to 1600 nm. By tuning the nanoscale silicon structure, the
optical reflection peak wavelength and intensity are changed, making the surface to have different reflectivity and
apparent colors. Parameters that affect the fabrication are evaluated. Optical properties of various pore depths are
discussed. The relation between the surface optical properties with the spatial features of the photon trapping
nanostructures is examined. The tunable photon trapping silicon structures have potential applications in enhancing the
performance of semiconductor photoelectric devices.ope>
Improvement of energy conversion efficiency of solar cells has led to innovative approaches, in particular the
introduction of nanopillar photovoltaics [1]. Previous work on nanopillar Si photovoltaic has shown broadband reduction
in optical reflection and enhancement of absorption [2]. Radial or axial PN junctions [3, 4] have been of high interest for
improved photovoltaic devices. However, with the PN junction incorporated as part of the pillar, the discreteness of
individual pillar requires additional conductive layer that would electrically short the top of each pillar for efficient
carrier extraction. The fragile structure of the surface pillars would also require a protection layer for possible
mechanical scratch to prevent pillars from breaking. Any additional layer that is applied, either for electrical contact or
for mechanical properties may introduce additional recombination sites and also reduce the actual light absorption by the
photovoltaic material. In this paper, nanopore Si photovoltaics that not only provides the advantages but also addresses
the challenges of nanopillers is demonstrated. PN junction substrate of 250 nm thick N-type polycrystalline Si on P-type
Si wafer is prepared. The nanopore structure is formed by using anodized aluminum oxide (AAO) as an etching mask
against deep reactive ionic etching (DRIE). The device consists of semi-ordered pores of ~70 nm diameter.
In this paper, a unique nanoscrew Si structure is presented. The nanoscrew surface is made by anodized aluminum oxide
(AAO) mask formation followed by extended deep reactive ionic etching (DRIE). Dense random zig-zag pillar
structures that represent screw shapes are formed, with 1 um in height and the bottom base width ranging from 100 nm
to 250 nm. The tip of the nanoscrews have radius of curvature even lower than 10 nm. The apparent naked-eye view of
the nanoscrew surface, which only consists of nanopatterned N-type single crystalline Si is diffusively green. The optical
properties of nanoscrew Si with and without metal deposition is presented as discussion in applications for SERS.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.