AVS 47th International Symposium
    Surface Science Wednesday Sessions
       Session SS-WeP

Paper SS-WeP5
Alloy Formation at the Co-Al Interface for Thin Co Films Deposited on Al(100) and Al(110) at Room Temperature

Wednesday, October 4, 2000, 11:00 am, Room Exhibit Hall C & D

Session: Poster Session
Presenter: R.J. Smith, Montana State University
Authors: R.J. Smith, Montana State University
N.R. Shivaparan, Montana State University
M.A. Teter, Montana State University
Correspondent: Click to Email
High-energy ion backscattering spectroscopy and channeling (HEIS), combined with x-ray photoelectron spectroscopy (XPS) and low energy electron diffraction (LEED) were used to characterize the evolution of the Co-Al interface for thin Co films deposited on Al(001) and Al(110) surfaces at room temperature. This interface is of particular interest because of the possible applications for tunneling magnetoresistive junctions and the associated fabrication processes such as oxidation of Al films deposited on magnetic thin films. For the Al(001) surface, measurements of the backscattered ion yields from Al and Co show that substrate Al atoms are continuously displaced for Co coverages up to about 3 ML as the interface alloy forms. Cobalt metal eventually covers the mixed interface. Based on XPS intensity analysis, we conclude that a CoAl-like phase forms at the interface. A very diffuse LEED pattern with large spots and high background was observed after a deposition of 7.6 ML of Co coverage. For the Al(110) surface, intermixing of Co and Al atoms was observed up to 5 ML of Co deposition, where Co metal begins to cover the surface. No LEED spots were observed for any Co coverage exceeding 0.2 ML on the Al(110) surface. A Volmer-Weber type growth model for these interfaces was used with the XPS intensity data to characterize the morphology of the interfaces in both cases. In neither case was Co diffusion into the bulk Al substrate observed at room temperature. These results are briefly compared with similar measurements for Ni and Fe films on Al surfaces. Work supported by NSF Grants DMR9409025 and DMR9710092.