METAL-DEPENDENT FERMI-LEVEL MOVEMENT IN THE METAL SULFUR-PASSIVATED INGAP CONTACT/

A high resolution core level photoemission study on the metal contact formed on S-passivated n-InGaP(100) surface reveals that the species p roduced by the chemical reaction of the deposited metal atoms with the surface atoms induce the gap states responsible for the Fermi level m ovement. The initial sulfur passivation of n-InGaP(100) surface effici ently reduced the Sap states within the band gap and flattened the ban d bending by 0.6 eV relative to the sputter-cleaned surface. When the metals such as Al(Au) are deposited on the S/InGaP(100) surface, it wa s found that the deposited Al(Au) reacted with monosulfides resulting in the Al-sulfide (the remaining defective In-polysulfides) which seem to be the origin of the gap states. (C) 1997 American Vacuum Society.