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In this study, the authors deposited silicon oxynitride films by Radio Frequency Plasma Enhanced Chemical Vapour Deposition (RF PECVD) method. The research explores the relationship between the deposition process parameters and the optical properties of the deposited SiO x N y films. The optical constants of SiO x N y films were measured and calculated by spectroscopic ellipsometry method. Additionally, the authors investigated the possibility of controlling the deposited film composition by the flow ratio of different gaseous precursors: ammonia (NH 3 ), diluted silane (2%SiH 4 /98%N 2 ), nitrous oxide (N 2 O) and nitrogen (N 2 ). The gas mixture introduced to the working chamber during the growth of the film has the influence on the Si-O and Si-N bonds formation and the ratio between these bonds determines the refractive index of the deposited film.

Optimized fabrication of submicron-sized features in gallium nitride (GaN) with the use of inductively coupled plasma (ICP) dry etching, based on SiCl 4 / Cl 2 /Ar gas mixture, is presented. Dense periodic patterns, i.e., 400-nm-period gratings, were transferred into a gallium nitride waveguide under different etching conditions. ICP power, radiofrequency (RF) power, chamber pressure, and Ar/Cl 2 gas mixing ratio were altered during the experiment. Depths of fabricated grating couplers up to 670 nm were achieved. The most suitable etching conditions are discussed with the assessment based on etching selectivity, scanning electron microscopy (SEM) observation of grating tooth slope, hard-mask erosion process, and etched surface morphology.

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