Characterization of the Surface Layer of Metal-Semicouductor Contacts by Means of X-ray Photoelectron Diffraction

Abstract

The X-ray photoelectron diffraction (XPED) method has been applied to the characterization of metal-semiconductor interfaces. For AufGaAs(110), Ge/GaAs(110) and Au/Ge(110) systems, the crystal regularity at the interface has been determined by the XPED method. The XPED patterns reveal that epitaxial growth of the deposited metal atoms takes place on the semiconductor surfaces in certain temperature ranges, while the structural regularity of these atoms disappears at elevated temperatures. The XPED patterns similar to those for the clean substrates are observed after the diffusion of the deposited metal atoms into the bulk. It is also shown that the XPED method can determine the atomic sites in the substitution reactions which take place at the interfaces: in the case of Au/GaSb(110), it is revealed that the Au atoms are substituted for Ga atoms after annealed at 540°C; in the case of Au/Ge/Ga As(110), it is found that both Ga and As atoms are replaced by Ge atoms, resulting in a Ge layer which has Ga and As atoms in its lattice sites. These investigations have proved that XPED is one of the most powerful and promising techniques for the characterization of the surface layer of metal-semiconductor contacts and will provide knowledge which will be useful for the practical device technology.