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 ZrO2 grown by ALD (atomic layer deposition), and having each thickness in the range 7–20 nm. These are: metal -insulator-semiconductor (MIS) Au/ZrO2/doped Si, and metal -insulator-metal (MIM) Au/ZrO2/Pt/doped Si, Pt/ZrO2/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 ZrO2 thickness of 15 nm. In the case of the MIS diodes the ideality factor was 1.56 and |2Pr| = 20.6 µC/cm2, while in the case of the MIM diodes the best diodes were Pt/ZrO2/Pt/ with an ideality factor of 2.03 and |2Pr| = 47.9 µC/cm2 and a leakage current in the range 10–50 fA. The subthreshold swing of 31.6 mV/decade and an on/off ratio of 107 show that these ZrO2 -based MIM diodes are an excellent candidate for low-power logic applications.