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Benefiting from the nonvolatile and fast programming operations of ferroelectric materials, ferroelectric synaptic transistors (FSTs) are promising in neuromorphic computing. However, it is challenging to realize conductance with a large dynamic range (Gmax/Gmin) and multilevel states simultaneously under low energy consumption. Here, solution-processed indium oxide (In2O3) synaptic transistors gated by ferroelectric Hf0.5Zr0.5O2(HZO) are proposed for the first time to address the above problems. Excellent synaptic characteristics were realized through the delicately regulated ferroelectric phase and good inhibition of charge injection in ferroelectric bulk and ferroelectric/semiconductor interface. Long-term potentiation/depression (LTP/D) up to 101 effective conductance states and excellent endurance (>1000 cycles) with large Gmax/Gmin= 32.2 were successfully mimicked under a low energy consumption of 490 fJ per spike event. Besides, the simulation achieved 96.5% recognition accuracy of handwriting digit, which is the highest record for existing FSTs. This work provides a new pathway for developing low-cost, high-performance, and energy-efficient FSTs.

1. Ferroelectric polarization value and o-/t- mixed phase fraction of HZO thin films can be largely enhanced by implementing W capping electrode. 2. Less wake-up effect (10.1%) and superior fatigue properties up to 1.5 × 1010 cycles were obtained for W/HZO/W capacitor. 3. The influence of the top electrode on the ferroelectricity of metal/HZO/metal capacitor is more important than that of the bottom electrode. This paper reports the improvement of electrical, ferroelectric and endurance of Hf 0.5 Zr 0.5 O 2 (HZO) thin-film capacitors by implementing W electrode. The W/HZO/W capacitor shows excellent pristine 2 P r values of 45.1 μC/cm2 at ±6 V, which are much higher than those of TiN/HZO/W (34.4 μC/cm2) and W/HZO/TiN (26.9 μC/cm2) capacitors. Notably, the maximum initial 2 P r value of W/HZO/W capacitor can reach as high as 57.9 μC/cm2 at ±7.5 V. These strong ferroelectric polarization effects are ascribed to the W electrode with a fairly low thermal expansion coefficient which provides a larger in-plane tensile strain compared with TiN electrode, allowing for enhancement of o-phase formation. Moreover, the W/HZO/W capacitor also exhibits higher endurance, smaller wake-up effect (10.1%) and superior fatigue properties up to 1.5 × 1010cycles compared to the TiN/HZO/W and W/HZO/TiN capacitors. Such improvements of W/HZO/W capacitor are mainly due to the decreased leakage current by more than an order of magnitude compared to the W/HZO/TiN capacitor. These results demonstrate that capping electrode material plays an important role in the enhancement of o-phase formation, reduces oxygen vacancies, mitigates wake-up effect and improves reliability. [Display omitted] [ABSTRACT FROM AUTHOR]

The poor endurance of the ferroelectric (FE) HfO2(Fe-HfO2) material-based FE field-effect transistor (Fe-FET) remains a major challenge for its future commercial production. Here we propose a high-κinterface seed layer (SL) in the metal-FE-insulator-semiconductor (MFIS) gate stack to address this issue. We fabricated Hf0.5Zr0.5O2(HZO) FE thin films on various high-κdielectric SLs, including ZrO2, HfO2, (HfO2)0.75(Al2O3)0.25(HAO), and Al2O3, and investigated their microstructures, ferroelectricity, and memory characteristics in the MFIS devices. The results show that the nucleation and growth of the FE orthorhombic phase in HZO films are affected not only by the surface energy but also by the microstructure of the high-κSL. Additionally, we clarified the role of the high-κSL on the memory characteristics of the MFIS devices, which were reasonably explained by the accurately calculated interface electric field. Finally, we realized a good tradeoff between the FE polarization and interface charge injection in the MFIS device with HAO high-κSL, demonstrating a large FE window (> 1.0 V), excellent retention (> 1.6×104s), and endurance cycles (> 105). The results will provide valuable ideas to overcome the challenge of endurance in the Fe-HfO2-based FeFET and contribute to developing other high-performance electron devices with Fe-HfO2films grown on a dielectric SL.