FABRICATION OF 2-DIMENSIONAL INP PHOTONIC BAND-GAP CRYSTALS BY REACTIVE ION ETCHING WITH INDUCTIVELY-COUPLED PLASMA

We fabricated two-dimensional (2D) InP photonic band-gap crystals by r eactive ion etching (PIE) with a SiCl4/Ar inductively coupled plasma ( ICP) chemistry, and characterized their reflective characteristics in the optical wavelength region by Fourier-transformed infrared reflecti on absorption spectrometry (FTIR-RAS). The photonic band-gap crystals consisted of a periodic array of parallel air rods of circular cross s ection whose intersections with a perpendicular plane form a triangula r lattice in InP substrates. Prior to the fabrication of the periodic array of air rods, the photonic band structure for electromagnetic wav es was calculated theoretically in the sample structure and was predic ted to appear in the optical wavelength region. In RIE with the SiCl4/ Ar ICP chemistry, we systematically investigated the InP etch rate and the etch selectivity of InP over SiO2 as functions of various etching parameters, to fabricate deep air rods with a vertical profile. The e ffect of the N2O addition to the SiCl4/Ar ICP chemistry was investigat ed and it was revealed that the addition of a small amount of N2O resu lts in an improvement in the vertical profile with a slight increase i n the InP etch rate. The InP etch rate and the etch selectivity of InP over SiO2 depended strongly on the SiCl4 flow rate. In FTIR-RAS measu rements, characteristic features were observed in tile optical wavelen gth region, depending on the diameter of the air rods. Behaviors of th e features were discussed in relation to theoretically calculated dens ities of states.