Current transport in high-barrier IrSi/Si Schottky diodes

The forward and reverse current-voltage (I-V) characteristics of IrSi/Si Schottky diodes have been measured in the temperature range from 100 to 300 K. Above 200 K the forward I-V characteristic is highly ideal and obeys the thermionic-emission theory including image-force lowering of the barrier. Below 200 K, carrier recombination in the depletion layer contributes to the current transport. Carrier recombination is also responsible for the soft behavior of the reverse I-V characteristic. The temperature dependence of the barrier height is identical to that of the indirect band gap in silicon, implying that the Fermi level is pinned at the interface by a high density of interface states. This is in agreement with the observation that the position of the quasi-Fermi-level at the interface is constant with applied bias and not swept through the interface states. The possible nature of these states is discussed.