Design and Fabrication of Modified L3 Two-Dimensional Silicon Photonic Crystal Lita Rahmasari*, Mohd Faizol Abdullah, Ahmad Rifqi Md Zain and Abdul Manaf Hashim
Physics Education Department, Universitas Sebelas Maret, Surakarta, Indonesia
MIMOS Semiconductor (M) Sdn Bhd, Technology Park Malaysia, 57000, Kuala Lumpur,
Malaysia
Institute of Microengineering and Nanoelectronics, Universiti Kebangsaan Malaysia, 46300, Bangi, Malaysia
Malaysia-Japan International Institute of Technology, Universiti Teknologi Malaysia,
Kuala Lumpur, Malaysia
Abstract
Because the gaps in photonic crystals (PhC) can trap fluid and change the refractive index, they are intriguing for use in optofluidic sensors. In this study, we redesigned the cavity region and waveguide of PhC to decrease photon leakage. A finite-difference time-domain method is used to model and simulate Si PhC with L3 cavity structure on the silicon-on-insulator substrate. The optimized Si PhC L3 cavity is created with a lattice pitch ratio of 0.30 with a hexagonal array arrangement of 17x15. The fabrication of L3 Photonic Crystal using a combination of electron beam lithography (EBL) and reactive ion etching (RIE) processes is reported. The optimum exposure dose of EBL process was found to be in 240 mikroCoulomb/cm^2 due to small enlargement of hole diameter after pattern development process. The anisotropic etching and isotropic etching were achieved at low and high reaction pressures, respectively. As expected, the etching rate increases with time and RF power. A relatively smooth and well-defined nanoholes of photonic crystal has been obtained at RF power of 100 W and reaction pressure of 0.08 Torr. For preliminary measurement, we test the fabricated the modified L3 Photonic Crystal in ambient air, the Si PhC L3 cavity structure exhibits a high Q-factor of about 15,000 and a resonance wavelength,Lamda-res, of about 1560 nm. Due to the close proximity, silicon photonic crystal exhibits a slight variation in hole radius of about 3.33% from the intended dimension. This research highlights the importance of design optimization and fabrication technique to achieve a high-quality factor of optical device.
Keywords: modified L3 Si PhC, electron beam lithography, reactive ion etching
