Etching and Template Stripping of Nanoscale Trigonal Pyramids

Nanoscale tetragonal plasmonic pyramids can exhibit enhanced electromagnetic fields at their tip, however the four-fold symmetry of the tetragonal pyramid can reduce these effects. Trigonal pyramids are expected to result in higher electromagnetic field enhancements at their tip due to the three-fold symmetry of the pyramid. Tetragonal plasmonic pyramids are currently fabricated via template stripping metals from KOH etched silicon etch pits. Hydrofluoric acid has been shown to etch micron scale trigonal etch pits in z-cut quartz, but they have not been fabricated on the nanoscale, due to under etching of the mask. We will discuss the fabrication of nanoscale trigonal pyramids and calculate their electric field enhancements compared to tetragonal pyramids.