Influence of the interface structure on the barrier height of homogeneous Pb/n-Si(111) Schottky contacts

Unreconstructed $\mathrm{Pb}/n{-}\mathrm{Si}(111)-(1 \times 1)^{i}$ interfaces may be prepared by evaporation of thick Pb films onto $\mathrm{Si(111):Pb}{-}(\sqrt{3} \times \sqrt{3}) \mathrm{R}30^{\circ}$ surfaces at room temperature. Current-voltage and capacitance-voltage characteristics of such $\mathrm{Pb}/n{-}\mathrm{Si}(111){-}(1 \times 1)^{i}$ Schottky contacts were measured in the temperature range between 140 and 300 K. The experimental data are analyzed by applying the thermionic-emission theory of inhomogeneous metal-semiconductor contacts as well as the "standard" thermionic-emission theory. From both methods the Schottky barrier height of laterally homogeneous $\mathrm{Pb}/n{-}\mathrm{Si}(111){-}(1 \times 1)^{i}$ contacts results as 0.724 eV. This value is by 74 meV larger than the previously observed barrier heights of laterally homogeneous $\mathrm{Pb}/n{-}\mathrm{Si}(111){-}(7\times 7)^{i}$ interfaces. Similar differences were reported for $(1\times 1)^{i}-$unreconstructed and $(7\times 7)^{i}-$reconstructed Al- and $mathrm{Ag}/n{-}\mathrm{Si}(111)$ contacts. The reduced barrier heights of all these $(7\times 7)^{i}$ interfaces are explained by the electric dipole associated with the stacking faults of $7\times 7$ reconstructions at $\mathrm{Si}(111)$ surfaces and interfaces