Relating spatially resolved maps of the Schottky barrier height to metal/semiconductor interface composition

The Schottky barrier height (SBH) is mapped with nanoscale resolution at pure Au/Si(001) and mixed Au/Ag/Si(001) interfaces utilizing ballistic electron emission microscopy by acquiring and fitting spectra every 11.7 nm × 11.7 nm over a 1 μm × 1 μm area. The SBH distributions for the mixed interfaces are about four times broader than the pure gold interface and have a complex structure arising from the incomplete intermixing and its effects on the scattering of hot electrons. The maps of the barrier heights and amplitudes for the mixed samples are inhomogeneous with localization attributed to the disordered mixture of the Au and Ag. A method to calculate ratio of the Au to Ag Schottky barrier heights is presented and discussed in relationship to the interface composition. These results demonstrate how the Schottky barrier height is a function of position at the interface, and how mapping can capture the electrostatic nature of these and possibly other mixed metal-semiconductor interfaces.