  In this work, we present an investigation of the Ag-PPP (polyparaphenylene)
interface using ballistic electron emission microscopy. Our work is the first
successful application of the BEEM technique to metal-organic interfaces. We
observe nanometer scale injection inhomogeneities. They have an electronic
origin, since we find corresponding Schottky barrier variations. We also
determine the transmission function of Ag-PPP interface and find that it agrees
qualitatively with the theoretical calculations for a metal-phenyl ring
interface. We conclude that charge transport across inhomogeneous barriers
needs to be considered for understanding electronic transport across
metal-organic interfaces and organic device characteristics.
