| dc.description.abstract | This thesis focus on the mid-infrared optical thin films including germanium (Ge), silicon monoxide (SiO) and silicon nitride (SiN) thin films. The difference from the conventional thermal evaporation process, these films were prepared by ion beam assisted deposition (IAD) process and expected to obtain the desirable properties at lower temperature. These films were analyzed using the infrared variable angle spectroscopic ellipsometry, Fourier transform infrared spectrometry, UV–NIR spectrophotometer, X-ray photoelectron spectrometry, scanning electron microscopy, atomic force microscopy, X-ray diffraction transmission electron microscopy and nano indenter. The influences of ion bombardment on the structural properties, such as composition, crystalline, and microstructure, and on the mid-infrared optical properties of these films were investigated.
The results showed that compared the conventional thermal evaporation process, the mid-infrared optical and structural properties of Ge and SiO thin films could be effectively improved by using the selective conditions of the ion beam voltage and current density in the IAD process. In addition, the SiN thin film with good optical property could be obtained using the IAD technique. Furthermore, the mid-infrared edge filter and anti-reflection coating, which were prepared by using the IAD process, also exhibited the desirable optical performance. These results presented in this work indicated that the IAD technique would have a positive effect on the optical and structural properties of the infrared thin films.
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