To fundamentally solve the bottleneck of Von Neumann's computing architecture, a neuromorphic thin-film transistor (NTFT) employing Pb(Zr, Ti)O3 (PZT) was investigated. The indium gallium zinc oxide (IGZO) channel back gate TFT structure was chosen to solve the diffusion of atoms that form a channel layer during the annealing process for crystallization of PZT. A post-deposition process with IGZO after annealing PZT and using an oxide-based material as a channel structure can minimize the diffusion phenomenon of junction materials and oxygen together, which leads to a high and reliable performance of the NTFT. The basic operations of synapses short-term memory (STM) and long-term memory (LTM) were also analyzed to confirm the application of a neuromorphic device. The high dielectric constant and polarization properties of Pb(Zr, Ti)O3 (PZT) allow the power consumption of spike signals used in spike dependent plasticity change to be reduced to 10 pJ. Moreover, a wide dynamic range of Gmax / Gmin ≅ 1000 was obtained, and the channel conductance was maintained over 40000 seconds. The optimized pulse achieved multi-level states (>32), which made the learning process efficient. This study verified that the PZT-TFT structure has a high potential and merits for neuromorphic devices.

To improve performances of nonvolatile charge trap flash memory devices, we propose an in situ Hf0.5Zr0.5O2 (HZO)/HfO2/Al2O3 stacked structure, which is compatible for Si with the metal–oxide–semiconductor (MOS) process based on all atomic layer deposition. Since the appropriate bandgap difference between Al2O3 and HfO2, stable charge trap operation is achieved. High-quality ferroelectric HZO film characteristics were showed by minimizing defects and Si diffusion through the sub-layer of Al2O3/HfO2. Therefore, HZO as a blocking layer enhances the memory performance of the charge trap structure due to its specific polarization effect. The proposed device has the high polarization characteristics of HZO (2Pr > 20 μ C/cm2) along with a MOS-cap window (>4 V), good retention capability (>10 years), fast program/erase response operation times (<200 μs), and strong durability (>105 cycles) while operating as a form of single level cell. By comparing Al2O3 and ferroelectric HZO as a blocking layer of the charge trap device, we confirmed that the HZO/HfO2/Al2O3 multi-layer structure had excellent characteristics according to various memory performance indicators. Our proposed high-performance charge trap flash memory can be employed in various applications, including Si-based three-dimensional structures with artificial intelligence systems.

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