Study of interfacial chemistry between metals and their effects on electronic systems

We studied the electrical properties of a large number of metal p type diodes which were fabricated by in situ metal deposition on atomically clean InP (110) surfaces in ultra high vacuum. Schottky barrier heights were determined from current-voltage (I-V) and capacitance-voltage (C-V) measurements. We found a small, but significant range in barrier heights (0.76 eV to 0.98 eV). Comparison of these p-type results to our earlier work on n-type surfaces shows that for these interfaces, Fermi level of n-type and p-type samples is pinned at the same energy within the bandgap. These results are similar to those previously reported by us for the GaAs interfaces prepared under the same conditions (only the absolute values of the pinning energies are different). Our results indicate that Schottky barrier models that use metal-independent interface states and potential normalization conditions (i.e., natural band lineups) can predict the general trends in the interface Fermi level pinning behavior. They fail, however, to provide quantitative agreement with experiment. We applied a theoretical method to determine the natural band lineups at the interface (using a scheme due to O.K. Anderson) and found that the use of work functions or electronegativities gives analogous correlations.