Pd-Al2O3-Si capacitors with Ru nanocrystals are fabricated and electrically characterized for nonvolatile memory application.While keeping the entire insulator Al2O3thickness fixed,the memory window has a strong dependence on the tunneling layer thickness under low operating voltages,whereas it has weak dependence under high operating voltages.As for the optimal configuration comprised of 6-nm tunneling layer and 22-nm blocking layer,the resulting memory window increases from 1.5 V to 5.3 V with bias pulse increasing from 10 5s to 10 2s under±7 V.A ten-year memory window as large as 5.2 V is extrapolated at room temperature after±8 V/1 ms programming/erasing pulses.