Origin of Schottky barriers in gold contacts on GaAs110

Phys Rev Lett. 2004 Nov 12;93(20):206801. doi: 10.1103/PhysRevLett.93.206801. Epub 2004 Nov 10.


Gold contacts on n-type GaAs(110) have been investigated using scanning tunneling microscopy and spectroscopy in cross-sectional configuration. In spatially resolved current voltage spectroscopy the Schottky barrier potential is visible. We find signatures of delocalized gap states at the interface decaying into the semiconductor and observe a defect density at the interface below 3 x 10(13) cm(-2). Both findings support that the Fermi level pinning at the Au/GaAs(110) interface is dominated by metal-induced gap states.