AN INVESTIGATION OF THE ELECTRICAL AND CHEMICAL-PROPERTIES OF INTIMATE METAL-INYAL1-YAS(100) INTERFACES

The electrical and chemical properties of the interfaces formed at roo m temperature, between the surface of epitaxial n-type InyAl1-yAs(100) and a selection of metals have been studied. Highly ideal Au, Ag, Cu, and In diodes exhibiting the highest reported barriers (0.78-0.91 eV) , measured by the current-voltage (I-V) technique, have been obtained by forming intimate contacts on atomically clean, lattice matched, mol ecular beam epitaxy grown InyAl1-yAs/InP(100). The formation of Au- an d In-InyAl1-yAs interfaces has been investigated using x-ray photoemis sion spectroscopy, showing that in both cases the Fermi level is pinne d at the surface prior to metal deposition. The deposition of both In and Au overlayers initiated the selective removal of As from the inter face to segregate on the metal surface; however the presence of these metals on the semiconductor surface produced no further Fermi shift. T hese observations, in conjunction with the barrier heights measured by the I-V technique, are discussed in the context of currently supporte d models of Schottky barrier formation.