Surface properties of Sc–O/W( [formula omitted]) system as emitter at room and high temperatures

Abstract

Surface characterization of an Sc–O/W(1 0 0) system as a Schottky emitter was carried out by low-energy electron diffraction (LEED) analysis, Auger electron spectroscopy (AES) and work function measurement. LEED and AES measurements were successfully performed at 1400 K, the operating temperature of the Sc–O/W(1 0 0) Schottky emitter. The results revealed that the atomic arrangement, composition and chemical bonding state of the Sc–O/W(1 0 0) surface show no change between room temperature (RT) and 1400 K when the Sc–O/W(1 0 0) surface is cooled to RT from 1400 K after oxygen processing. Investigation of the surfaces at RT as well as at 1400 K indicated that the reduced work function of 3.2 eV attained at 1400 K was maintained even when the sample temperature was lowered to RT. These properties of the Sc–O/W(1 0 0) system suggest the practical applicability of the Sc–O/W(1 0 0) emitter to a cold field emitter as well as to a Schottky emitter as reported.