GRADIENT INTERFERENCE OPTICAL FILTERS MANUFACTURED FROM ORGANOSILICONE COMPOUNDS WITH THE RF PECVD TECHNIQUE
- 1 Lodz University of Technology, Institute of Materials Science and Engineering, Lodz, Poland
Chemical structure and optical properties of thin coatings synthesized from organosilicone precursors by means of radio frequency plasma enhanced chemical vapor deposition were studied by means of Fourier transform infrared spectroscopy, scanning electron microscopy and variable angle spectroscopic ellipsometry. Both precursors, namely hexamethyldisilazane (HMDSA) and tetramethyldisilazane (TMDSA) were used to deposit films under conditions of different proportions of oxygen to nitrogen in the reaction mixture. In both cases, changing that proportion from 0% to 100% resulted in a substantial change of refractive index of the resulting coating, from 2.22 to 1.65 and from 2.31 to 2.03 for HMDSA and TMDSA, respectively. The results obtained allowed us to design and to manufacture a “rugate” interference optical filter with a gradient value of refractive index. For that purpose, HMDSA precursor was selected as one enabling a change of refractive index in a much broader range.