We have studied the Er and ErSi2contacts onp‐Si. A correlation is found between the barrier height and the presence of an interfacial oxide layer. Samples with a thin interfacial oxide (∼ 3 A˚) exhibit a barrier height of 0.68 eV. In contrast, samples without any detectable interfacial oxide show a higher barrier height of ∼0.8 eV. The barrier heights were determined by current‐voltage measurements and the thicknesses of the interfacial oxide were measured by the16O(d,&agr;)14N nuclear reaction technique.