Surface electronic properties of GaSe-covered Si(111) upon UHV thermal desorption of the GaSe epitaxial layer

Clean 7 × 7 reconstructed 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 a sample was sequentially Joule-heated under ultra-high vacuum from room temperature to above 700°C. Upon raising the temperature, the changes of the surface electronic properties were studied by photoemission yield spectroscopy. Several steps in the dissociative desorption of GaSe were observed. The corresponding work function and band offsets as deduced from photoyield results are presented and discussed.