Contact potentials and barrier heights in gold‐silicon and aluminum‐silicon contacts

摘要

We have measured the contact potential difference (cpd) between evaporated films of gold, aluminum, and real silicon surfaces using the intersection method. The gold/silicon cpd for the most consistent set of results was 0.2 eV to within ±0.1 eV. The aluminum/silicon cpd was 0.7 eV to within ±0.2 eV. The accuracy was limited mainly by work‐function drift due to surface contamination during measurement. The working pressure was 2×10-5 Torr. The intersection method essentially measures the integrated energy distribution of an electron beam in the cutoff region. It was observed that the integrated energy distribution of the collected electrons depended strongly on the collector surface probably due to surface (patch) fields. The barrier heights of the gold‐silicon contacts were measured using the differential capacitance method. In the majority of cases there was no correlation between barrier heights and cpd suggesting that the barrier height is determined primarily by surface states.