Early stages of interface formation of C60 on GaAs(1 0 0)

We present a detailed investigation of the electronic properties of C60 grown on GaAs(1 0 0) substrates, as a function of the fullerene coverage, from the very early stages of interface formation up to the development of a bulk-like fullerene film. We monitor the chemical interactions and the energy levels alignment by means of X-rays, ultraviolet and inverse photoemission spectroscopies. The two latter techniques allow to investigate the electronic structure close to the Fermi level. Energy levels alignment at the interfaces of C60 with p-doped and GaAs(1 0 0) are obtained and discussed.