Park Yongjin, Lee Jong-Ho, Lee Jung-Kyu, Kim Sungjun
Division of Electronics and Electrical Engineering, Dongguk University, Seoul 04620, South Korea.
The Department of Electrical and Computer Engineering and Inter-University Semiconductor Research Center (ISRC), Seoul National University, Seoul 08826, South Korea.
J Chem Phys. 2024 Feb 21;160(7). doi: 10.1063/5.0190195.
This study presents findings indicating that the ferroelectric tunnel junction (FTJ) or resistive random-access memory (RRAM) in one cell can be intentionally selected depending on the application. The HfAlO film annealed at 700 °C shows stable FTJ characteristics and can be converted into RRAM by forming a conductive filament inside the same cell, that is, the process of intentionally forming a conductive filament is the result of defect generation and redistribution, and applying compliance current prior to a hard breakdown event of the dielectric film enables subsequent RRAM operation. The converted RRAM demonstrated good memory performance. Through current-voltage fitting, it was confirmed that the two resistance states of the FTJ and RRAM had different transport mechanisms. In the RRAM, the 1/f noise power of the high-resistance state (HRS) was about ten times higher than that of the low-resistance state (LRS). This is because the noise components increase due to the additional current paths in the HRS. The 1/f noise power according to resistance states in the FTJ was exactly the opposite result from the case of the RRAM. This is because the noise component due to the Poole-Frenkel emission is added to the noise component due to the tunneling current in the LRS. In addition, we confirmed the potentiation and depression characteristics of the two devices and further evaluated the accuracy of pattern recognition through a simulation by considering a dataset from the Modified National Institute of Standards and Technology.
本研究结果表明，一个单元中的铁电隧道结（FTJ）或电阻式随机存取存储器（RRAM）可根据应用进行有意选择。在700°C退火的HfAlO薄膜表现出稳定的FTJ特性，并且可以通过在同一单元内形成导电细丝而转换为RRAM，也就是说，有意形成导电细丝的过程是缺陷产生和重新分布的结果，并且在介电薄膜发生硬击穿事件之前施加合规电流可实现后续的RRAM操作。转换后的RRAM表现出良好的存储性能。通过电流-电压拟合，证实了FTJ和RRAM的两种电阻状态具有不同的传输机制。在RRAM中，高电阻状态（HRS）的1/f噪声功率比低电阻状态（LRS）高约十倍。这是因为HRS中额外的电流路径导致噪声分量增加。FTJ中根据电阻状态的1/f噪声功率与RRAM的情况正好相反。这是因为在低电阻状态下，由于普尔-弗伦克尔发射产生的噪声分量与隧穿电流产生的噪声分量相加。此外，我们证实了这两种器件的增强和抑制特性，并通过考虑来自美国国家标准与技术研究院修改版数据集的模拟进一步评估了模式识别的准确性。
