X-ray-scattering studies of the interfacial structure of Au/GaAs

Abstract

We present results of an x-ray-reflectivity measurement on a Au film, 1000-\AA{} thick, in situ epitaxially grown on GaAs by molecular-beam epitaxy. Roughness of both air/Au and Au/GaAs interfaces was obtained from the specular-reflectivity curve. Interfacial height fluctuations of the air/Au interface were found to be correlated to those of the Au/GaAs interface. The correlation of the height fluctuations was obtained quantitatively from the diffuse scattering profile. Satellite peaks in the rocking curves at small incident angles were also observed and attributed to the correlated roughness and to the dynamic scattering effects. Upon heating the sample to 400 \ifmmode^\circ\else\textdegree\fi{}C, the interface became rougher and the interfacial correlation was lost. We speculate that the interfacial changes were caused by interdiffusion at elevated temperatures.