Physical and electrical properties of high- k PrTi_xO_y nanocrystal memories

We proposed a high- k metal-oxide insulator oxide-silicon-type structure with a PrTix Oy nanocrystal layer grown on the tunneling oxide of a memory device using reactive radio frequency sputtering. We found that the PrTix Oy nanocrystal film annealed at 800°C exhibited a large memory window of 3.2 V in the capacitance-voltage curve and good data retention up to 104 s (only a 5 and 10% charge loss at 25 and 85°C, respectively) due to deep trapping in the PrTix Oy layer. This phenomenon is attributed to a well-crystallized PrTix Oy structure and the decrease of the Pr-silicate thickness observed by X-ray diffraction and X-ray photoelectron spectroscopy, respectively.