Surface characterization of zirconia-coated tungsten Schottky emitters by using RHEED, AES, and TOF-SIMS

Temperature dependences of surface periodicity on the Zr/O/W(100) and (110) of a Schottky emitter tip have been directly measured by RHEED equipment improved by installing a heating stage and an imaging system. Reversible structural change from c(2× 4) + c(4 × 2) to p(1 × 1) has been observed only in (100). Bonding states of Zr-O, Zr-W, and O-W on Zr/O/W(100), (110), and (112) in planar-samples have been evaluated by AES and TOF-SIMS. We propose a structural model of a Zr/O/W surface in which Zr atoms are adsorbed on O atoms in W-O layers formed on the W single crystal.