Impact of the Crystal Phase of ZrO₂ on Charge Trapping Memtransistor as Synaptic Device for Neural Network Application
In this work, we investigated the effects of the crystal phase of ZrO<sub>2</sub> on charge trapping memtransistors (CTMTs) as synaptic devices for neural network applications. The ZrO<sub>2</sub> deposited through thermal (t-ZrO<sub>2</sub>) atomic layer depositi...
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| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
IEEE
2020-01-01
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| Series: | IEEE Journal of the Electron Devices Society |
| Subjects: | |
| Online Access: | https://ieeexplore.ieee.org/document/9091548/ |
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| Summary: | In this work, we investigated the effects of the crystal phase of ZrO<sub>2</sub> on charge trapping memtransistors (CTMTs) as synaptic devices for neural network applications. The ZrO<sub>2</sub> deposited through thermal (t-ZrO<sub>2</sub>) atomic layer deposition (ALD) and plasma (p-ZrO<sub>2</sub>) ALD were analyzed using an X-ray diffractometer, which indicated that the t-ZrO<sub>2</sub> consisted of pure cubic phase, whereas p-ZrO<sub>2</sub> consisted of both cubic and tetragonal phases. Through X-ray photoelectron spectroscopy analysis, we then constructed the energy band diagram of the gate stacks. The <inline-formula> <tex-math notation="LaTeX">$\Delta \mathrm E_{C}$ </tex-math></inline-formula> of t- and p-ZrO<sub>2</sub> with respect to tunneling and blocking Al<sub>2</sub>O<sub>3</sub> were 1.84 and 1.19 eV respectively. Because of the relatively large <inline-formula> <tex-math notation="LaTeX">$\Delta \text{E}_{\mathrm{ C}}$ </tex-math></inline-formula> of t-ZrO<sub>2</sub>, the window of the flat band voltage (<inline-formula> <tex-math notation="LaTeX">$\text{V}_{\mathrm{ FB}}$ </tex-math></inline-formula>) shift extracted from charge trapping capacitors was enlarged by 591.9 mV more than the one using p-ZrO<sub>2</sub> as the charge trapping layer. Retention was also improved by 10.4% after <inline-formula> <tex-math notation="LaTeX">$10^{5}$ </tex-math></inline-formula> s in the t-ZrO<sub>2</sub> case. Finally, we fabricated the CTMTs with the gate stack of the t-ZrO<sub>2</sub> case and demonstrated their characteristics as synaptic devices. With the optimization of pulse schemes, we reduced the nonlinear factors of depression (<inline-formula> <tex-math notation="LaTeX">${\alpha } _{\mathrm{ d}}$ </tex-math></inline-formula>) and potentiation (<inline-formula> <tex-math notation="LaTeX">${\alpha } _{\mathrm{ p}}$ </tex-math></inline-formula>) from −6.72 and 6.47 to 0.03 and 0.01 respectively, enlarged the ON/OFF ratio from 15.6 to 70.4 and increased the recognition accuracy from 27.6% to 86.5% simultaneously. |
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| ISSN: | 2168-6734 |