The Optical and Thermo-Optical Properties of Non-Stoichiometric Silicon Nitride Layers Obtained by the PECVD Method with Varying Levels of Nitrogen Content

In this paper, we investigated the optical and thermo-optical properties of a-SiN_x:H layers obtained using the PECVD technique. SiN_x:H layers with different refractive indices were obtained from silane and ammonia as precursor gases. Surface morphology and chemical composition studies were investigated using atomic force microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy and energy dispersive spectrometry methods. Spectroscopic ellipsometry was used to determine the optical indexes, thicknesses and optical bandgap of the films. The main purpose was to identify the thermo-optical characteristics of layers with different refractive indexes. Thermo-optical studies were performed to determine the temperature hysteresis of optical parameters. These measurements showed that after annealing up to 300 °C and subsequent cooling, the value of optical parameters returned to the initial values.