A Photoemission Study of Al and An Overltayers on Se/GaAs(100)

抄録

Deposition of Al and Au was performed on a Se treated GaAs(100) surface. The deposition of Al at low coverages results in a significant reduction in band bending that is interpreted in terms of further passivation of the Se treated GaAs surface. At intermediate coverages, band bending is consistent with what one would expect on the basis of Schottky limit. In this intermediate thickness regime, the formation of metallic Ga resulting from a Ga-Al exchange reaction producing a thermodynamically stable Al_xSe_y interlayer is observed. At higher Al coverages, band bending is increased and is accompanied by Se surface segregation and a band bending which is slightly higher than expected from an ideal Al/GaAs interface. In a manner similar to Al deposition, deposition of Au results in segregation of only one Se species and provides further evidence on the structure of the Se/GaAs surface. Finally, Schottky barrier heights of 0.3 and 0.9 eV were realized for AI/Se/GaAs and Au/Se/GaAs respectively. This result suggests the Se passivated surface provides a wide degree of freedom in the fabrication of GaAs based Schottky barrier diodes.