An xray photoemission spectroscopy study of the role of sample preparation on band bending at the interface of Al with poly(pphenylene vinylene)We have investigated the interface formation of Ca with poly(p-phenylene vinylene) (PPV) using x-ray photoemission spectroscopy. The most significant part of our findings was the very late occurrence of band bending at the Ca/PPV interface and the lack of strong reaction between the Ca overlayer with the PPV substrate, indicating that the Schottky barrier formation in Ca/PPV was a slow process. The late barrier formation at the Ca/PPV interface may be due to the shielding by surface oxygen impurities, part of which underwent calcium oxide formation at the interface. 7894

The surface structure of a clean MoS 2 (0002) and an in situ Cs surface-doped MoS 2 (0002) has been studied using high-resolution X-ray photoemission spectroscopy. The X-ray photoelectron diffraction (XPD) patterns of the Mo 3d 5/2 and S 2p core levels from a clean, well-ordered MoS 2 (0002) show forward focusing intensity maxima along the directions of nearest neighbors in MoS 2 in both the polar and azimuthal angle scans. The XPD patterns in the azimuthal angle scan exhibit a pronounced photoelectron intensity maximum at every 60°, reflecting the 6-fold rotational symmetry of the basal plane. In addition, because of the finite electron escape depth and the short-range order of the scattered photoelectrons, the azimuthal scans of both the Mo 3d 5/2 and the S 2p core levels further display the 3-fold rotational symmetry of the trigonal prismatic local structure, which MoS 2 (0002) possesses. The deposition of Cs onto the MoS 2 (0002) surface at room temperature did not introduce any significant changes either in the low-energy electron diffraction or in the XPD patterns, indicating the absence of Cs-induced surface relaxation, but a new photoemission was observed 1.6 eV above the valence band edge of MoS 2 , which corresponds to the Cs 6s photoelectron shared with the MoS 2 lattice. Thus Cs/MoS 2 represents an electron donor-acceptor (EDA) surface complex.

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An xray photoemission spectroscopy study of the role of sample preparation on band bending at the interface of Al with poly(pphenylene vinylene)

No abstract