With the goal of improving photo-absorption of photovoltaic device and for plasmonic application we have fabricated
nanopillar black silicon devices through etching-passivation technique which does not require any photomask and whole
wafer scale uniformity is achieved at room temperature in a short time. We have carried out thorough optical
characterization for nanopillar black silicon devices to be used for solar cell and plasmonic applications.
Cathodoluminescence (CL), current dependent CL spectroscopy, photoluminescence (at room temperature and 77 K),
Raman spectroscopy, reflectance and absorption measurement have been performed on the device. A thin layer of Ag is
deposited to render with plasmonic property and the plasmonic effect is probed using surface plasmon enhanced
fluorescence, angle dependent reflectance measurements, high resolution cathodoluminescence (CL), surface enhanced
Raman spectroscopy (SERS) measurement and Fluorescence Lifetime Imaging Microscopy (FLIM) experiment. We
obtained reduction in optical reflection of ~ 12 times on b-Si substrate from UV to NIR range, the nanostructured
fluorescence enhancement of ~40 times and the Raman scattering enhancement factor of 6.4×10<sup>7</sup>.
We demonstrate surface plasmon-induced enhancements in optical imaging and spectroscopy on silver coated silicon
nanocones which we call black silver substrate. The black silver substrate with dense and homogeneous nanocone forest
structure is fabricated on wafer level with a mass producible nanomanufacturing method. The black silver substrate is
able to efficiently trap and convert incident photons into localized plasmons in a broad wavelength range, which permits
the enhancement in optical absorption from UV to NIR range by 12 times, the visible fluorescence enhancement of ~30
times and the NIR Raman scattering enhancement factor up to ~10<sup>8</sup>. We show a considerable potential of the black silver
substrate in high sensitivity and broadband optical sensing and imaging of chemical and biological molecules.one)
We demonstrated gold-coated polymer surface enhanced Raman scattering (SERS) substrates with a pair of complementary structures-positive and inverted pyramid array structures fabricated by a multiple-step molding and replication process. The uniform SERS enhancement factors over the entire device surface were measured as 7.2×104 for positive pyramid substrates while 1.6×106 for inverted pyramid substrates with Rhodamine 6G as the target analyte. Based on the optical reflection measurement and finite difference time domain simulation result, the enhancement factor difference is attributable to plasmon resonance matching and to SERS "hot spots" distribution. With this simple, fast, and versatile complementary molding process, we can produce polymer SERS substrates with extremely low cost, high throughput, and high repeatability.