Structure, adhesion, and stability of metal/oxide and oxide/oxide interfaces

Abstract

Studies of several model metal/oxide and oxide/oxide interfaces were carried out by depositing ultra-thin metal thins on single crystal oxide substrates. The specific systems that were characterized include K/TiO{sub 2}, K{sub 2}O/TiO{sub 2}, Al/TiO{sub 2}, Al{sub 2}O{sub 3}/TiO{sub 2}, and K/NiO. The interface electronic structure and bonding interactions were determined with x-ray and uv photoelectron spectroscopies (XPS and UPS) and the structure and morphology was analyzed with low energy and high energy electron diffraction (LEED and RHEED) and atomic force microscopy (AFM). The two metal overlayers studies, K and Al, were found to strongly interact with the single crystal oxide substrates. Given adequate thermal energy, the metals became oxidized and substoichiometric TiO{sub 2} and NiO compositions were created near the interface. Defects were found to have a major influence on interface structure. The construction of the thin film deposition/RHEED analysis chamber was completed during the past year, and a versatile sample transfer and heating system was implemented. Three graduate students participated in the project, the results were presented at three national meetings, and one manuscript was submitted for publication.