Room-temperature Schottky diodes and the onset of the ferroelectricity in ZrO2/Si heterostructures

In this paper we investigate three different heterostructures, all based on ZrO 2 grown by ALD (atomic layer deposition), and having each thickness in the range 7–20 nm. These are: metal -insulator-semiconductor (MIS) Au/ZrO 2 /doped Si, and metal -insulator-metal (MIM) Au/ZrO 2 /Pt/doped Si, Pt/ZrO 2 /Pt/doped Si. We have measured their current-voltage characteristics at room temperature and their associate ferroelectricity before and after a rapid thermal annealing (RTA) treatment. High performances nanoscale Schottky diodes were obtained after RTA at the ZrO 2 thickness of 15 nm. In the case of the MIS diodes the ideality factor was 1.56 and |2P r | = 20.6 µC/cm 2 , while in the case of the MIM diodes the best diodes were Pt/ZrO 2 /Pt/ with an ideality factor of 2.03 and |2P r | = 47.9 µC/cm 2 and a leakage current in the range 10–50 fA. The subthreshold swing of 31.6 mV/decade and an on/off ratio of 10 7 show that these ZrO 2 -based MIM diodes are an excellent candidate for low-power logic applications.