COMPARISON OF ELECTRON-AFFINITY AND SCHOTTKY-BARRIER HEIGHT OF ZIRCONIUM AND COPPER-DIAMOND INTERFACES

In this study, the evolution from diamond surfaces to metal-diamond in terfaces has been examined. The electron affinity and the Schottky bar rier height of a few Angstrom thick films of Zr and Cu deposited in ul trahigh vacuum (UHV) onto IIb substrates were correlated. Prior to met al deposition, the diamond surfaces have been cleaned by different ann eals and plasma treatments in UHV, and the surfaces were characterized by Auger electron spectroscopy and atomic force microscopy. The initi al surfaces were terminated with oxygen, or free of chemisorbed specie s. Ultraviolet photoemission spectroscopy was employed to determine wh ether the samples exhibited a positive electron affinity or a negative electron affinity (NEA) before and after metal deposition. For Zr, th e Schottky barrier height was found to change very little with the pre sence or absence of chemisorbed species at the interface. A NEA was ob served for Zr on diamond independent of the surface termination. Howev er, for Cu, the surface cleaning prior to metal deposition had a more significant effect. The Schottky barrier height changed strongly depen ding on the chemical species at the interface. A NEA was only detected for Cu on clean diamond surfaces. The differences between Zr on the o ne hand and Cu on the other are correlated with differences in interfa ce chemistry and structure. (C) 1997 American Vacuum Society.