Oxygen migration around the filament region in HfOx memristors
Ge-Qi Mao,
Kan-Hao Xue,
Ya-Qian Song,
Wei Wu,
Jun-Hui Yuan,
Li-Heng Li,
Huajun Sun,
Shibing Long,
Xiang-Shui Miao
Affiliations
Ge-Qi Mao
Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, Hubei, China
Kan-Hao Xue
Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, Hubei, China
Ya-Qian Song
Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, Hubei, China
Wei Wu
Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, Hubei, China
Jun-Hui Yuan
Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, Hubei, China
Li-Heng Li
Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, Hubei, China
Huajun Sun
Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, Hubei, China
Shibing Long
School of Microelectronics, University of Science and Technology of China, Hefei 230026, Anhui, China
Xiang-Shui Miao
Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, Hubei, China
The exact composition and structure of conductive filaments in hafnia-based memristors are still not fully understood, but recent theoretical investigations reveal that hexagonal HfOx phases close to the h.c.p. Hf structure are probable filament candidates. In this work we list h.c.p. Hf, Hf6O, Hf3O and Hf2O as possible phases for the filament in hafnia memristors. Their differences in lattice parameters, electronic structures and O charge states are studied in details. Migration of O ions for both in-plane and out-of-plane directions in these phases is investigated using first-principles calculations. Both single-phase supercells and filament-in-dielectric models are used for migration barrier calculations, while the latter is proven to be more accurate for the c-direction. The migration of O ions is fastest in metal Hf, while slowest in Hf2O. The existence of O interstitials in Hf tends to hinder the transport of O.
