Depozice a charakterizace gradientních tenkých vrstev pro optické pokrytí
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Diplomová práce se zabývá tenkými gradientními vrstvami SiOxNy s gradientnímprofilem indexu lomu vytvořenými metodou iontového naprašování (Ion Beam Sputtering) s iontovou asistencí.Teoretická část uvádí do tématiky interference na tenké vrstvě, depozice tenkých vrstev a jejího monitoringu. Dále se zabývá shrnutím dosavadních poznatků v tématu gradientních tenkých vrstev, jejich využití a jejich charakterizace.V experimentální části byla na homogenních vrstvách určena závislost indexulomu deponované vrstvy na průtoku kyslíku asistenčním iontovým dělem. Pro účelyvyhodnocení byl vytvořen skript v MATLAB na fitování modelových elipsometrických a spektrofotometrických spekter do experimentálně změřených spekter. V návaznosti byly deponovány gradientní vrstvy s dvěma různými profily indexu lomu, kde gradient indexu lomu ve vrstvách byl tvořen změnou průtoku kyslíku asistenčním dělem. Porovnání teoretických a experimentálních spekter prokázalo, že vzniklý profil odpovídá průtoku kyslíku v průběhu depozice. Diskutována byla i citlivost výsledků na posunu hodnot profilu indexu lomu při zachování jeho tvaru. Na základě získaných poznatků byly úspěšně deponovány dva úzkopásmové rugate filtry. Jejich výsledná reflektance byla porovnána s očekávanou a byly diskutovány možnosti optimalizace celého procesu.
The thesis is devoted to gradient refractive index thin films of SiOxNy deposited by ion-beam sputtering combined with ion assistance.The theoretical part of the thesis consists of an introduction to thin-film interference, deposition and monitoring of thin films. It summarizes the state-of-the-art knowledge of the field of gradient thin-film deposition and characterization. The experimental part of the thesis consists of three sections. In the first one, we studied the effect of the flow of oxygen through the assistance ion source on optical properties of a homogeneous thin layer. The acquired experimental data were fitted with a theoretical model in terms of their ellipsometric and spectrophotometric properties by using MATLAB. Subsequently in the second section, two gradient films, each with a different profile of refractive index, were sputtered. The gradient of the refractive index was created by varying the oxygen flow. Comparison of the simulated and experimental spectra has proven that the deposited thin-film profiles agrees with the expected refractive index change corresponding to the oxygen flowduring the deposition. The sensitivity of the fitting to the offset of the refractive-index profile was discussed. On the basis of the findings, two narrow-band rugate filters were succesfully fabricated. Their reflectivity was compared with the expected one. Finally, we discuss possible options of the process optimization.
The thesis is devoted to gradient refractive index thin films of SiOxNy deposited by ion-beam sputtering combined with ion assistance.The theoretical part of the thesis consists of an introduction to thin-film interference, deposition and monitoring of thin films. It summarizes the state-of-the-art knowledge of the field of gradient thin-film deposition and characterization. The experimental part of the thesis consists of three sections. In the first one, we studied the effect of the flow of oxygen through the assistance ion source on optical properties of a homogeneous thin layer. The acquired experimental data were fitted with a theoretical model in terms of their ellipsometric and spectrophotometric properties by using MATLAB. Subsequently in the second section, two gradient films, each with a different profile of refractive index, were sputtered. The gradient of the refractive index was created by varying the oxygen flow. Comparison of the simulated and experimental spectra has proven that the deposited thin-film profiles agrees with the expected refractive index change corresponding to the oxygen flowduring the deposition. The sensitivity of the fitting to the offset of the refractive-index profile was discussed. On the basis of the findings, two narrow-band rugate filters were succesfully fabricated. Their reflectivity was compared with the expected one. Finally, we discuss possible options of the process optimization.
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Ion Beam Sputtering, Ion Beam Assisted Deposition, SiOxNy, optická tenká vrstva, gradientní profil indexu lomu, rugate filter, Ion Beam Sputtering, Ion Beam Assisted Deposition, SiOxNy, optical thin film, refractive-index gradient profile, rugate filter