Local current-voltage characteristics of rough TiO2 layers on TiSi2.

The nature of charge transport across rough, insulating layers of TiO2 on TiSi2 is investigated using conducting atomic force microscopy. The conducting tip, the insulating layer, and the metallic TiSi2 layer constitute a metal-insulator-metal system. This system exhibits a strong correlation between the topographic image and the current image. Based on this observation, the dependence of current-voltage characteristics on the local thickness of the TiO2 layer is examined and analyzed on the basis of the Fowler-Nordheim tunneling mechanism. This analysis indicates that both field emission and trap assisted tunneling contribute to the conduction mechanism. Evidence of switching due to detrapping of charges is also seen in the I-V characteristics, confirming the role of trap states. [ABSTRACT FROM AUTHOR]