Electronic Structure and Charge-Trapping Characteristics of the Al2O3-TiAlO-SiO2 Gate Stack for Nonvolatile Memory Applications

Electronic Structure and Charge-Trapping Characteristics of the Al2O3-TiAlO-SiO2 Gate Stack for Nonvolatile Memory Applications

Discover Nano, April 2017

28410556

Wenchao Xu, Yang Zhang, Zhenjie Tang, Zhengjie Shao, Guofu Zhou, Minghui Qin, Min Zeng, Sujuan Wu, Zhang Zhang, Jinwei Gao, Xubing Lu, Junming Liu

In this work, high-k composite TiAlO film has been investigated as charge-trapping material for nonvolatile memory applications. The annealing formed Al2O3-TiAlO-SiO2 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 Al2O3-TiAlO-SiO2 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 Al2O3 and TiO2 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.