CHARACTERIZATION OF METAL-DIAMOND INTERFACES - ELECTRON-AFFINITY AND SCHOTTKY-BARRIER HEIGHT

In this study, the electron affinity and Schottky barrier height of th in Cu and Zr films on diamond (100) substrates were correlated by mean s of UV photoemission spectroscopy (UPS) measurements. Prior to metal deposition the diamond crystals were cleaned by a 1150 degrees C or 50 0 degrees C anneal in UHV, and the surfaces were characterized by AES and AFM. This resulted in surfaces terminated with oxygen or Free of c hemisorbed species. By means of UPS it was found that whether a metal did induce a negative electron affinity (NEA) on a diamond surface was dependent on the surface preparation before metal deposition and on t he metal work function. In particular, the Schottky barrier height for clean surfaces was lower than for surfaces terminated by oxygen. Meta l-diamond interfaces exhibiting a NEA had a lower Schottky barrier hei ght than those exhibiting a positive electron affinity. These effects were attributed to different interfacial layers, Field emission measur ements were performed before and after metal deposition. For all cases a reduction in the threshold electric field was observed upon metal o vergrowth. (C) 1997 Elsevier Science S.A.