The interface formation of PTCDA on Se-modified GaAs 100/ surfaces

The interface formation between the molecular beam deposited molecular semiconductor, 3,4,9,10-perylenetetracarbo- xylic dianhydride PTCDA., and Se-treated GaAs 100.- 2=1.surface was investigated by soft X-ray photoemission spectroscopy SXPS.using synchrotron radiation. For room temperature growth, no chemical bond is observed. At elevated sample temperature up to 3508C after the growth, all PTCDA except one monolayer desorbs from the surface. A loss of Se dimer atoms on top of the surface, which is in accordance with the number of anhydride oxygen atoms of PTCDA in a unit cell, indicates the reaction with PTCDA molecules upon annealing. The growth mode and the band banding upon PTCDA deposition on Se-treated GaAs 100.are also discussed. q2000 Elsevier Science B.V. All rights reserved.