INHOMOGENEOUS SCHOTTKY BARRIERS AT AG SI(111) AND AG/SI(100) INTERFACES/

We have measured current-voltage and capacitance-voltage characteristi cs of epitaxial Si(111)7x7-Ag, Si(111)(root 3x root 3)R30 degrees-Ag, Si(100)2x1-Ag, and polycrystalline Ag/Si interfaces, using different d oping levels for both n- and p-type silicon wafers. Our data strongly suggest that the Schottky barrier heights (SBHs) are spatially nonunif orm. The distribution of local effective SBHs at the epitaxial interfa ces is modeled by a summation of a single Gaussian, representing the s pread in SBH for the majority of the contact, and two half-Gaussians w hich represent the high- and low-barrier tails of the full distributio n. Despite the fact that the average SBHs of the epitaxial interfaces are hardly structure dependent, the SBH distributions are very broad a nd markedly different for each interface. The polycrystalline interfac es are characterized by a narrower SBH distribution centered at a subs tantially smaller mean. We argue that the electrical inhomogeneity is related to structural inhomogeneity at the interface which is a direct consequence of the kinetics and mode of growth of Ag on Si. (C) 1996 American Institute of Physics.