SURFACE ELECTRONIC-PROPERTIES OF GASE-COVERED SI(111) UPON UHV THERMAL-DESORPTION OF THE GASE EPITAXIAL LAYER

Clean 7 x 7 reconstructed Si(111) surfaces have been epitaxially cover ed with a film of layered GaSe, The GaSe layers are parallel to the (1 11) plane of the Si substrate. Such a sample was sequentially Joule-he ated under ultra-high vacuum from room temperature to above 700 degree s C. Upon raising the temperature, the changes of the surface electron ic properties were studied try photoemission yield spectroscopy. Sever al steps in the dissociative desorption of GaSe were observed. The cor responding work function and band offsets as deduced from photoyield r esults are presented and discussed.