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T. Fujimoto and I. Kojima
[Jpn. J. Appl. Phys., Vol.34, p.2461, 1995]
The vapor deposition of Pd on graphite was carried out in an oxygen radical atmosphere. The resulting surfaces were analyzed by an AES (JAMP30; JEOL), a XPS (ESCALAB-XL220i; VG) and a STM (Nanoscope II; DI). Pd deposited on HOPG in the oxygen gas atmosphere were showed a similar behavior to the deposition under UHV. On the other hand, the surface images of the sample prepared with oxygen radicals is dramatically different from others (Fig. 1). Most surface are covered with the thin film (thickness 0.6nm). At the dark area in Fig. 1 a lattice image with 0.25nm periodicity were observed, which indicates that initial graphite surfaces are partly remaining. The result of XPS measurement for the Pd ultra thin film showed that a portion of the Pd was in an oxidized state while other Pd atoms were in a metallic state. It can be surmised that the Pd thin film could be grown due to the affinity of the Pd deposits to the graphite surface being increased by the inclusion of oxygen atoms.
Fig. 1. Top view STM image of the Pd deposited graphite surface prepared under oxygen radical atmosphere.