Lyu Benzheng, Choi Yongsuk, Jing Hongyue, Qian Chuan, Kang Hyunseok, Lee Sungjoo, Cho Jeong Ho
SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon, 16419, Republic of Korea.
Department of Chemical and Biomolecular Engineering, Yonsei University, Seoul, 03722, Republic of Korea.
Adv Mater. 2020 Apr;32(17):e1907633. doi: 10.1002/adma.201907633. Epub 2020 Mar 18.
MXenes, an emerging class of 2D transition metal carbides and nitrides with the general formula M X T (n = 1-4), have potential for application as floating gates in memory devices because of their intrinsic properties of a 2D structure, high density-of-states, and high work function. In this study, a series of MXene-TiO core-shell nanosheets are synthesized by deterministic control of the surface oxidation of MXene. The floating gate (multilayer MXene) and tunneling layer (TiO ) in a nano-floating-gate transistor memory (NFGTM) device are prepared simultaneously by a facile, low-cost, and water-based process. The memory performance is optimized via adjustment of the thickness of the oxidation layer formed on the MXene surface. The fabricated MXene NFGTMs exhibit excellent nonvolatile memory characteristics, including a large memory window (>35.2 V), high programming/erasing current ratio (≈10 ), low off-current (<1 pA), long retention (>10 s), and cyclic endurance (300 cycles). Furthermore, synaptic functions, including the excitatory postsynaptic current/inhibitory postsynaptic current, paired-pulse facilitation, and synaptic plasticity (long-term potentiation/depression), are successfully emulated using the MXene NFGTMs. The successful control of MXene oxidation and its application to NFGTMs are expected to inspire the application of MXene as a data-storage medium in future memory devices.
MXenes是一类新兴的二维过渡金属碳化物和氮化物，通式为MₙXₙ₋₁T（n = 1 - 4），由于其二维结构、高态密度和高功函数的固有特性，在存储器件中作为浮栅具有应用潜力。在本研究中，通过对MXene表面氧化的确定性控制合成了一系列MXene-TiO核壳纳米片。纳米浮栅晶体管存储器（NFGTM）器件中的浮栅（多层MXene）和隧穿层（TiO）通过简便、低成本的水基工艺同时制备。通过调整MXene表面形成的氧化层厚度来优化存储性能。制备的MXene NFGTM表现出优异的非易失性存储特性，包括大存储窗口（>35.2 V）、高编程/擦除电流比（≈10）、低关断电流（<1 pA）、长保持时间（>10⁵ s）和循环耐久性（300次循环）。此外，使用MXene NFGTM成功模拟了包括兴奋性突触后电流/抑制性突触后电流、双脉冲易化和突触可塑性（长时程增强/抑制）在内的突触功能。MXene氧化的成功控制及其在NFGTM中的应用有望激发MXene在未来存储器件中作为数据存储介质的应用。
