Schottky barrier height lowering induced by CoSi₂ nanostructure

Abstract

CoSi₂ nanostructures were formed through thermal agglomeration by annealing ultrathin Co film on Si substrate at high temperatures. The characteristics of the Schottky diodes with CoSi₂ nanostructures capped by a Pt layer were measured and fitted using thermionic emission theory. All the diodes have a ideality factor less than 1.1. The results show that the Schottky barrier height of these diodes significantly decreases as the annealing temperature for CoSi₂ agglomeration increases. The barrier height lowering is correlated with the agglomeration of CoSi₂ film and the formation of CoSi₂ nano-islands. The thermal field emission may be the major reason to cause barrier lowering. Although the Schottky contact interface consists of both CoSi₂ nano-islands and Pt film whose individual contact barrier height to Si is very different, the current-voltage-temperature measurements reveal that the interface homogeneity is not degraded as expected. The study demonstrates that the CoSi₂ nanostructures can both lower the Schottky barrier height and form an ideal Schottky contact with a Pt capping layer.