N2-Based ICP-RIE Etching for InP-Based Photonic Crystal Membranes

Adding N₂ into Cl₂-based plasma discharges during the etching of InP-based photonic crystal in ICP-RIE system is shown to produce smooth sidewalls through the passivation of the etched surfaces. Here we present that the addition of BCI₃ into this discharge allows to produce smooth and also vertical profiles in InP-based PhC structures. Positive ion current densities have been measured to characterize the plasma, and provide a perspective to understand the etching mechanism. An one missing row (Wl) photonic crystal membrane-waveguide fabricated by CI₂/N₂/BCI₃ gas mixture exhibits a low propagation losses value of 35 dB/cm while operating below the light line.