Optik dalga kılavuzları uygulamaları için silisyum oksinitrat tabakalar

Silicon oxynitride layers, aimed to serve as the core material for optical waveguides operating at 1.55/mi, were grown by a PECVD technique using SİH4, N20, and NH3 as precursor gases. The films were deposited at 350 °C, 13.56 MHz RF frequency, and 1 Torr pressure by varying the flow rates of N2O and NH3 gases. The resulting refractive indices of the layers varied between 1.47 and 2.0. The compositional properties of the layers were analyzed by FTIR and ATR infrared spectroscopy techniques. A special attention was given to the N-H bond stretching absorption at 3300-3400 cm-1, since its first overtone is known to be the main cause of the optical absorption at 1.55//m. An annealing study was performed in order to reduce or eliminate this bonding type. For the annealed samples the corresponding concentration was strongly reduced as verified by FTIR transmittance and ATR methods. A correlation between the N-H concentration and absorption loss was verified for silicon oxynitride slab waveguides. Moreover, a single mode waveguide with silicon oxynitride core layer was fabricated. Its absorption and insertion loss values were determined by butt-coupling method, resulting in low loss waveguides.Keywords: PECVD, Silicon oxynitride, FTIR, ATR, Waveguide, Optical absorption, Single mode, Prism coupling, Annealing. u