X-RAY PHOTOELECTRON DIFFRACTION STUDY OF YBAS GAAS(001) AND SCAS/GAAS(001) HETEROSTRUCTURES/

Polar angle distributions of core level photoemission intensities reco rded on YbAs/GaAs(001) and ScAs/GaAs(001) heterostructures are present ed. They allow first the surface roughness of thin YbAs overlayers to be seen, second to estimate the tetragonal distortion of a strained Sc As film and, third, the most interesting point, to demonstrate in a di rect fashion that the mixed (Yb-As) (010) planes of YbAs grow in the p rolongation of the As planes of GaAs. The results are compared to thos e obtained by other authors with various techniques. The main advantag e of the photoelectron diffraction method over the other techniques is that it can be performed on very thin epitaxial films (some monolayer s) directly in situ under ultrahigh vacuum.