FABRICATION, CHARACTERIZATION AND SIMULATION OF SUB-MICRON GRATING STRUCTURES FOR EXCITATION OF SURFACE PLASMON IN BIOSENSOR APPLICATIONS

• Main Author: SETIYA PRADANA (NIM: 10213098), JALU
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/22667
• Institution: Institut Teknologi Bandung

Surface Plasmon Resonance (SPR) is a resonance phenomenon between electron on the metal surface and the incident electromagnetic wave causing a quantized-plasmon oscillation. Due to this resonance, the electric field on the metal surface is much stonger in comparison to that of in the total internal reflection (TIR) case. Therefore, this SPR phenomenon has been investigated intensively in the last two decades for developing sensitively biosensing devices. There are four methods commonly applied to excite SPR wave, i.e. by using a prism, grating, waveguide coupler and nanoprticles. Among those methods, the method by using a grating offers more simplicity in instrumentation and fabrication cost condiserations. However, this method still need further study for understanding the SPR wave exciation and the measured SPR spectrum pattern particularly in grating with non-sinusoidal shape. This final report presents then experimental results on the fabrication of gratings for SPR wave excitation with periodicity in hundreds of nanometers (sub-micron) by using nano-imprint lithography method, which is aimed to effcetivile excite SPR wave spectrum in the visible light range. The fabricated structure is also analyzed by a simulation work based on the Rigorous Coupled-Wave Analysis (RCWA) method for calculating the SPR spectra. This method was chosen because its basic formulation uses the Fourier expansion, which is very convenient for analyzing any complex structure by representing it into various modes of its fundamental shape or sinusoidal structures. Grating with 500 nm and 700 nm with tens of nanometers of metal layer on the top of the gratings have been succesflly fabricated and characterized. They show SPR spectrum with the appearance of SPR dips both in the zero order and first zero order of diffractions, which shift to longer wavelength with increasing incident angle. The observed SPR spectra characterteristc and the appearance of these multi-dips are in agreement with general pattern of the SPR spectra from simulation results.