Schottky barrier diodes of yttrium and yttrium silicide were fabricated onp‐type (111) silicon. The barrier heights of the diodes determined byI‐Vmeasurements were correlated with heat treatments and interface conditions as determined by Auger composition depth profiles. The as‐deposited Y‐Si contact had a barrier height of 0.70 eV. During heat treatment at 300 °C, oxygen diffused into yttrium and formed Y2O3, resulting in a barrier height of 0.65 eV. Yttrium silicide was formed at 410 °C that lead to a Schottky barrier height of 0.60 eV.