Electronic Structure and Charge-Trapping Characteristics of the Al(2)O(3)-TiAlO-SiO(2) Gate Stack for Nonvolatile Memory Applications

In this work, high-k composite TiAlO film has been investigated as charge-trapping material for nonvolatile memory applications. The annealing formed Al(2)O(3)-TiAlO-SiO(2) dielectric stack demonstrates significant memory effects and excellent reliability properties. The memory device exhibits a large memory window of ~2.6 V under ±8 V sweeping voltage, and it shows only ~14% charge loss after more than 10 years’ retention, indicating excellent charge retention properties. The electronic structures of the Al(2)O(3)-TiAlO-SiO(2) have been studied by X-ray photoelectron spectroscopy measurements, and it reveals that the quantum well and the defect traps in TiAlO film can provide a >1.8 eV deep barrier for charge confinement in the TiAlO layer. The mixing between Al(2)O(3) and TiO(2) can increase the defects related to the under-coordinated Ti(3+) atoms, thereby enhancing the charge-trapping efficiency of the device. Our work implies that high-k TiAlO composite film is promising for applications in future nonvolatile charge-trapping memories.