Fabrication, characterization, and optical properties of gold nanobowl submonolayer structures.

We report on a versatile method to fabricate hollow gold nanobowls and complex gold nanobowls (with a core) based on an ion milling and a vapor HF etching technique. Two different sized hollow gold nanobowls are fabricated by milling and etching submonolayers of gold nanoshells deposited on a substrate, and their sizes and morphologies are characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Optical properties of hollow gold nanobowls with different sizes are investigated experimentally and theoretically, showing highly tunable plasmon resonance ranging from the visible to the near-infrared region. Additionally, finite difference time domain (FDTD) calculations show an enhanced localized electromagnetic field around hollow gold nanobowl structures, which indicates a potential application in surface-enhanced Raman scattering (SERS) spectroscopy for biomolecular detection. Finally, we demonstrate the fabrication of complex gold nanobowls with a gold nanoparticle core which offers the capability to create plasmon hybridized nanostructures.