SILICON(111) SURFACE-PROPERTIES UPON UHV THERMAL-DISSOCIATION OF A GASE EPITAXIAL LAYER

Clean 7X7 reconstructed and H-covered 1X1 Si(111) surfaces have been epitaxially covered with a film of layered GaSe. The GaSe layers are parallel to the (111) plane of the Si substrate. Such samples were sequentially Joule-heated under ultra-high vacuum from room temperature to above 700 degrees C. Upon raising the temperature, changes of the surface properties were studied by Auger electron spectroscopy, and low energy electron diffraction. Several steps in the dissociative desorption of GaSe were observed at temperatures which depended on the initial silicon surface preparation. It usually leads to a Ga-induced root 3 X root 3 R30 degrees reconstruction before a clean Si(111) surface is recovered.