Research on High Resolution Electron Microscope Observations without Specimen Damage

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1. Field emission electron gun for high voltage scanning transmission electron microscope A field emission electron gun was mounted on the 10OOkV scanning transmission electron microscope (STEIM), after improving a vacuum system and establishing a monitor-control system for monitoring and controlling the operating condition of the gun. A stable field emission of more than 50muA was obtained with a <310> orientation tungsten tip.2. Detection of various signal electrons A new YAG single crystal scintillator was developed for high-sensitivity electron detector which gives the sensitivity of 10 times as much as a conventional powdered-phosphor scintillator. A method was established as well for detecting inelastically scattered and unscattered electrons with high accuracy, by improving an electron energy analyzing system.3. Signal manipulation A theoretical investigation for better image quality of specimen structure revealed an appropriate manipulation among elastically scattered, inelasti … More cally scattered and unscattered electrons. A signal manipulation system was established by developing an interface for effective data acquisition and a system for manipulating among various electron signals. Signal manipulation was then applied to practical electron microscope observations, which verified the effectiveness of signal manipulation for noise elimination, contrast enhancement of specific specimen structure, identification of constituting elements and so on.4. Influence of current density of illumination electrons on the specimen damage and high resolution observations without damage Studies on intensity change of electron diffraction pattern of hexatriacontane indicated that STEM illumination with a fine electron probe of high current density gives less specimen damage than long-time illumination of conventional electron microscopy with low current density. It was found as well that high resolution STEM observations without specimen damage are possible for fine platinum particles in a carbon film which are easily subject to damage of migration, adhesion and crystallization in conventional electron microscopy mode observations. Less