Temperature dependence of a CrSi_2 Schottky barrier on n-type and p-type Si

摘要

Electrical transport through CrSi_2-Si Schottky junctions was studied by internal photoemission spectroscopy and electrical current-voltage (I-V) techniques in a wide temperature range. The apparent barrier height and the ideality factor derived by using thermionic emission theory were found to be strongly temperature dependent. Internal photoemission measurements yielded a weakly temperature-dependent barrier height for these samples. This difference between optical and electrical results shows that the optical transport was dominated by a single photoemission over the expected barrier at the junction while the electrical transport was determined by more than one current mechanism. For p-type substrates, the same barrier height values were obtained from both electrical and optical measurements in a much wider temperature range. A model based on the presence of more than one current channel and mechanisms was developed in order to describe the measured I-V curves of both types. It was assumed that the junction's interface contains small regions through which charge carriers can tunnel. Experimental results were reproduced reasonably well by using this approach. Some recent models proposed for the electrical transport in metal-semiconductor junctions are also discussed.