Phase contrast in transmission electron microscopy based on thin-film phase plates fabricated from metallic glasses

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Weak-phase objects generate only negligible contrast in in-focus bright-field transmission electron microscopy (TEM) images. It is therefore the overarching goal of this project to achieve phase contrast in TEM by implementation of thin-film phase plates fabricated from metallic glasses. Most thin-film phase plates consist up to now of amorphous carbon which suffer from quick degradation in the electron microscope and cannot be routinely applied, despite encouraging contrast enhancements for weak-phase objects. Metallic glasses with an amorphous structure are promising materials to replace amorphous carbon due to their high electrical conductivity and stability under high-energy electron irradiation. The tasks of the project comprise a) the selection of metallic glasses with a high tendency for glass formation and with high crystallization temperature, b) die fabrication of thin films with amorphous structure and homogeneous thickness by sputter deposition and c) the characterization of the thin-film microstructural properties by analytical TEM. The characteristics of the metallic-glass-based Zernike and Hilbert phase plates will be studied with regard to phase shift, transmission, cut-on frequency and long-term stability by using test samples and samples which show only weak TEM contrast. By introducing phase plates fabricated from metallic glasses we expect to achieve phase contrast with negligible artifacts over extended application times in the transmission electron microscope.