Ferroelectric undoped HfOxcapacitor with symmetric synaptic for neural network accelerator

Jun Dao Luo*, Yu Ying Lai, Kuo Yu Hsiang, Chia Feng Wu, Yun Tien Yeh, Hao Tung Chung, Yi Shao Li, Kai Chi Chuang, Wei Shuo Li, Chun Yu Liao, Pin Guang Chen, Kuan Neng Chen, Min Hung Lee*, Huang Chung Cheng

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


A plasma-based ferroelectric undoped HfOx capacitor is fabricated using plasma-enhanced atomic layer deposition (PE-ALD), and the multilevel characteristics of synaptic behavior are investigated. A gradual ferroelectric phase transition in the material is confirmed by grazing incidence X-ray diffraction (GI-XRD) for different O2 plasma periods. The metal-ferroelectric-metal (MFM) capacitor presents excellent remnant polarization (Pr) up to 13 μC/cm2 and a switching endurance of more than 108 cycles. Superior small potentiation/depression nonlinearity (αp/αd = -0.08/-1.66 for voltage modulation stimulation) for synaptic training and almost symmetry training curve (|αp - αd|) are obtained. High stability under multilevel operation with five consecutive cycles of alternating potentiation and depression is exhibited without significant polarization variation for each training step (pulse).

Original languageEnglish
Article number9339849
Pages (from-to)1374-1377
Number of pages4
JournalIEEE Transactions on Electron Devices
Issue number3
Publication statusPublished - 2021 Mar


  • Ferroelectric
  • multilevel
  • synaptic training
  • undoped HfO

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering


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