Abstract
Interfacial reactions between cobalt thin films and (001) GaAs have been studied by transmission electron microscopy, energy-dispersive analysis of x-rays in a scanning TEM, Auger electron spectroscopy and x-ray photoelectron spectroscopy. The completely reacted layer was found to be "β-Ga 2 0 3 /(CoGa, CoAs)/GaAs." The formation of a surface layer of β-Ga 2 O 3 and the use of encapsulated samples minimized As loss from the reacted layer. Both CoGa and CoAs were found to grow epitaxially on (001) GaAs. The orientation relationships between CoGa and GaAs were determined to be [001] CoGa//[001] GaAs and (220) CoGa//(220) GaAs. The Burgers vectors of interfacial dislocations were identified as 1/2 〈101〉 and 1/2 〈011〉 which are inclined to the (001) GaAs surface. Almost all of the CoGa films were found to be epitaxially related to the surface. No interfacial dislocations were observed in most of the epitaxial CoAs films which are considered to be pseudomorphic with respect to GaAs. The orientation relationships between CoAs and GaAs were determined to be [101] CoAs//[011] GaAs and (020) CoAs//(220) GaAs. Two-step annealing was found to be effective in promoting epitaxial growth. © 1988 The Metallurgical of Society of AIME.