STUDY OF IRON OVERLAYER ON SULFUR PASSIVATED GAAS(100) BY SYNCHROTRON-RADIATION PHOTOEMISSION

We have studied the interface electronic structures and the chemical r eaction of the Fe overlayer deposited on S-passivated GaAs(100). The c hemical bond and electronic structure are different from Fe/GaAs, and the reaction between As and Fe is weakened by S atoms. This is benefic ial to the magnetism in the interface. In the first stage of depositio n, Fe clusters is form near S atoms due to the large electronegativity of S. The S atoms remain at the interface with Fe coverage. Magnetic ordering feature is found at a coverage higher than 0.6 nm. According to the large exchange splitting in valence band spectra, we suggest th at Fe phase transition from bcc to fcc occurs with increasing coverage .