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Preparation of SiC Films and Thermodynamic Simulation of Optical Elements in EUV Detector

Author: SongZuo
Tutor: XieErQing；XieChangQing
School: Lanzhou University
Course: Optics
Keywords: silicon carbide plasma enhanced self-standing films transmission grating terrestrial X/EUV finite element thermal deformation
CLC: O436.1
Type: Master's thesis
Year: 2010
Downloads: 98
Quote: 1
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Abstract

As well known, Silicon carbide (SiC) has been considered as one of the next generation of semiconductor materials, due to its excellent physical and chemical properties, which make it wide applications in high-frequency, high-power, and high temperature optoelectronic devices. Based on their excellent mechanical and optical properties, this dissertation was mainly focused on applying SiC films as one of the important dispersion elements in the extreme ultraviolet detectors, i.e. transmission grating. Moreover, SiC should be one of the preferred materials that can be used as the key component of extreme ultraviolet (EUV) detectors, which can work under the extremely hard environment of Near-Earth space, owing to their high thermal conductivity, strong radiation resistance, high thermal capacitance, and excellent chemical inertness.In this dissertation, SiC films were prepared by using plasma enhanced chemical vapor deposition (PECVD). According as the requirements of the practical applications, SiC films were prepared under high temperatures on the single crystal Si (100) substrates. The films prepared under different process parameters were characterized by various techniques. Based on the results of the characterization of the samples, the CVD and annealing parameters have been further optimized. Finally, the high-quality self-supporting films with area of 5×5 cm2 were successfully prepared. Additionally, the technical processes of the preparation of this type self-supporting films and further applications in extreme ultraviolet transmission grating were discussed in details.Because the technical processes of the preparation of the extreme ultraviolet transmission grating using self-supporting SiC films are still under research, commercial PI films were used instead of SiC ones to prepare 2000 1/mm X/EUV transmission grating in the latter work. In order to meet the requirements of the EUV transmission grating spectrometer in Near-Earth space, a mechanical model based on the finite element method was used to simulate the thermal and coupling properties of the transmission grating. Based on the simulation under the influence of the temperature field from the Sun in Near-Earth space, the thermal distortion distribution was obtained for the transmission grating with different coefficient of thermal expansion. The results indicate that the average surface distortion of the transmission grating can reach up to 0.56μm under high-vacuum thermal environments, while the average longitudinal distortion, which often shows a significant impact on the period of the gratings, is 71.5nm. Generally, the thermal distortion will show a huge influence on the diffraction efficiency of the transmission grating, further lead to the reduced behaviors and accuracies of the spectroscopic instruments. Thus, based on the results by the finite element simulation, the techniques of the package and designs were further optimized to prepare the transmission gratings with longitudinal distortion of zero at the grating lines. Our research may provide some effective scientific basis and effective support for the application of 2000 1/mm X/EUV transmission gratings in the solar EUV radiation spectroscopy.

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CLC: > Mathematical sciences and chemical > Physics > Optics > Physical optics ( wave optics ) > Interference and diffraction
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