Nb-doped Gd_2O_3 as charge-trapping layer for nonvolatile memory applications

摘要

The charge-trapping properties of Gd_2O_3 with different Nb doping levels are investigated using an Al/Al_2O_3/Gd_2O_3/SiO_2/Si structure. Compared with the memory device with pure Gd_2O_3, the one with lightly Nb-doped Gd_2O_3 shows better charge-trapping characteristics, including higher programming speed (6.5V at +12V programming voltage for 10ms) and better retention property (92% retained charge at 85 ℃ after 10~4 s), due to its higher trapping efficiency that resulted from higher trap density and suppressed formation of a silicate interlayer at the Gd_2O_3/SiO_2 interface induced by the Nb doping. Moreover, the one with heavily Nb-doped Gd_2O_3 shows improvement in erasing behavior but worse retention and lower programming speed than the one with lightly Nb-doped Gd_2O_3. Further analysis reveals that the Nb-doping level determines the type of dominant trap in the Nb-doped Gd_2O_3, thus leading to different charge-loss mechanisms and charge-trapping characteristics.