Effects of charge storage dielectric thickness on hybrid gadolinium oxide nanocrystal and charge trapping nonvolatile memory

The characteristics of hybrid gadolinium oxide nanocrystal (Gd2O3-NC) and gadolinium oxide charge trapping (Gd2O3-CT) memories were investigated with different Gd2O3 film thickness. By performing the rapid thermal annealing on Gd2O3 films with different thickness, the Gd2O3-NCs with the diameter of 6–9 nm for charge storage, surrounded by the amorphous Gd2O3 (α-Gd2O3) layer, were formed. The α-Gd2O3 layer was considered to be the charge trapping layer, resulting in the large memory window of Gd2O3-NC/CT memories with thick Gd2O3 film. The charge trapping energy level of the Gd2O3-NCs and α-Gd2O3 layer was extracted to be 0.16 and 0.45 eV respectively by using the temperature-dependent retention measurement. Further, after a 106 program/erase cycling operation, the memory with thin Gd2O3 film can be predicted to sustain a 94% memory window of the first cycling one while the memory with thick Gd2O3 film suffered from a 30% charge loss because of the traps within the α-Gd2O3 layer. The Gd2O3 film thickness of 10 nm was optimized to exhibit superior performances of the Gd2O3-NC/CT memory, which can be applied into the nonvolatile memory.