Date of Graduation
Statler College of Engineering and Mineral Resources
Lane Department of Computer Science and Electrical Engineering
Advances in nanofabrication have made possible the development of novel nanophotonics based on Photonic Crystal (PhC) structures. Different types of biosensors have been proposed to take advantage of the unique optical properties of PhCs, which, when combined with microfluidics, provide an enabling approach for biomolecule analysis. In this thesis, nanofabrication of a new biosensor structure integrating a 2D PhC nanocavity resonator with an optofluidic channel is described. The recipes for e-beam lithography of PhC and PhC nanocavity patterns were optimized by carefully tuning the e-beam dose as well as control of the resist baking and development conditions. Two PhC fabrication processes based on pattern transfers by lift-off and etch-back were compared. The plasma etching of Si, GaN, and ITO were optimized to obtain fast etching rates, vertical profiles as well as high etch selectivities over different hard masks including Si3N4, SiO2, and Ni. Si, GaN and ITO PhC structures with airhole diameters in the range of 100-200 nm were fabricated using the developed processes. To facilitate the integration of the PhC structures with microfluidic channels, the PhC airholes were sealed with a SiO2 thin film formed by glancing angle deposition. By gradually reducing the flux angle toward normal during deposition, we successfully deposited uniform SiO2 capping layers with minimal material extended down into the PhC airholes. Finally, suspended Si PhC slabs were fabricated on a Si-on-Oxide substrate using an integrated procedure which consists of e-beam lithography, pattern transfer into Si by CF4 plasma etching, and a selective etch of the underlying SiO2 sacrificial layer in HF. The suspended PhC structure provides an important test bed for measuring resonant fluorescence of biomolecules in PhC nanocavities in the IR range.
Andagana Junta, Henry Bolivar, "Nanofabrication of Optofluidic Photonic Crystal Resonators for Biosensing" (2010). Graduate Theses, Dissertations, and Problem Reports. 3052.