Silicon on insulator photonic bandgap structures for future microphotonic devices

Silicon on insulator (SOI) substrates provide a naturally good template for the introduction of optics at the microelectronics device level, due to the high refractive index contrast between Si and SiO₂. If one is able to control the propagation of photons in the material, functional devices like, filters, modulators or resonant detectors can be envisioned. Furthermore recent progress showed efficient room temperature light emission from doped silicon material which opens now a route towards CMOS compatible silicon-based light emitters. In this work we will present the design, fabrication and optical characterisation of SOI based photonic crystals (PC). These structures have been fabricated using standard CMOS technology process and e-beam lithography. Optical characterisation was performed on a very wide wavelength range (1.1 to 1.7 μm). This was allowed by the coupling of a white light source in each waveguide through a cleaved edge of the sample and collecting the light from the other side of the waveguide. We will first present waveguide integrated PC microcavities and PC waveguides Results showing photonic bandgap (PBG) effects ie.: stop bands, cavity resonance and light guiding below and above the light cone will be presented together with band structure calculation by plane wave expansion techniques and transmission properties calculated by FDTD. Then, we will also present results on light emission in one dimensional and two dimensional PBG structures designed in order to change the emission rate and/or extraction of photons from the Si layer. Different structures have been studied: vertical microcavities, in-plane 2D hexagonal cavities and defect-less structures and results demonstrating strong light extraction enhancement will be shown.