A new cathode has been developed which shows similar electron emission characteristics as a previously reported Sc2O3 mixed matrix impregnated cathode (Sc2O3 MM Cathode). Contrary to the Sc2O3 MM cathode, the new cathode is resistive to prolonged heating at high temperatures and to ion bombardment. This has been made possible by applying to a standard impregnated cathode a tungsten thin-film containing about 5 weight percent Sc2O3. The electron-emission property is found to be strongly linked to the surface atom composition as well as to the distribution of surface atoms.

An impregnated cathode of a novel structure is proposed, fabricated, and evaluated. A thin tungsten film 100–400 nm in thickness containing various amounts of Sc2O3 is coated on a standard impregnated cathode composed of a porous tungsten body in which electron emissive materials are impregnated. The electron emission property measured with a diode configuration is found to be dependent on Sc2O3 content and surface atom distribution. Surface atom distribution is depicted by means of Auger electron spectroscopy. For high electron emission enhancement it is necessary for Sc2O3 content to be 2.5–6.5 wt. % and for a layer of the order of a monolayer in thickness composed of Ba, Sc, and O to develop on the cathode surface.

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The surface oxidation process of Si(100), and the distribution of intermediary oxidation states at the SiO2/Si interface have been extensively studied by high resolution (ΔE<0.3 eV) photoemission spectroscopy using synchrotron radiation. The results show that the ratio at the SiO2/Si interface for three intermediary states, Si3+, Si2+, and Si1+ (SiOx), is strongly dependent on SiO2 layer thickness. In particular, the proportion of Si3+ increases with the formation of the 0∼1 nm thick SiO2 layer. However, the three intermediary components at the interface are distributed with ratios of Si3+:Si2+:Si1+=7:2.5:1 in the oxidation stage where a SiO2 layer is formed over 1 nm.

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