ELECTRONIC-STRUCTURE AND CHEMICAL CHARACTERIZATION OF ULTRATHIN INSULATING FILMS

We report on the use of photoemission to probe the electronic structur e of ultrathin films. The electronic structure of Zr3N3 grown by low e nergy N-2(+) implantation in polycrystalline zirconium has been invest igated. The insulating characteristics of Zr3N4 as well as the metal-i nsulator phase transition in ZrNx, when x approaches 1.33, can be nice ly observed by photoemission during the implantation process. Other ex amples correspond to the understanding of oxide/oxide interfaces by in situ characterization of the growth of an oxide film on a dissimilar oxide. We have studied the electronic properties of the TiO2/SiO2 inte rface by examining the O 2p valence band and the O 2s and Ti 3p core l evels during growth of ultrathin films of TiO2 on SiO2. We report evid ence for the formation of cross linking oxygen ions to form Si-O-Ti bo nds at the interface. In addition we use the high sensitivity of the N i 2p XPS core level lineshape to the local co-ordination of the nickel atoms to study the interface NiO/MgO(100) by in situ characterization of the growth of ultrathin NiO films an MgO(100). (C) 1998 Elsevier S cience S.A. All rights reserved.