Direct correlations between iridium silicides and their Schottky barrier heights on Si have been studied by combining TEM observations and I-V and C-V measurements. It has previously been shown that three iridium silicides IrSi, Ir2Si3, and IrSi3 can be formed by annealing Ir films on Si at temperatures around 400, 600, and 960 °C, respectively. The Schottky barrier height of these silicides on 〈100〉 Si have been determined to be 0.93 eV (IrSi), 0.85 eV (Ir2Si3), and 0.94 eV (IrSi3). Along with the I-V measurement, a computer fitting of current transport across Schottky diodes has been used to analyze the I-V data so that the barrier height from nonideal diodes can be determined. The question of a parallel diode formed by a mixture of two phases at the contact area has also been addressed. It is shown that I-V measurements, which are very sensitive to the presence of a lower barrier phase, tend to give a lower barrier height than a corresponding C-V measurement since the latter depends on the major phase in the contact area.