2D MXene–TiO2 Core–Shell Nanosheets as a Data‐Storage Medium in Memory Devices

• Published in: Advanced materials (Weinheim) Vol. 32; no. 17; pp. e1907633 - n/a
• Main Authors: Lyu, Benzheng, Choi, Yongsuk, Jing, Hongyue, Qian, Chuan, Kang, Hyunseok, Lee, Sungjoo, Cho, Jeong Ho
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.04.2020
• Subjects: 2D MXenes; artificial synapses; Data storage; Endurance; floating‐gate; Materials science; Memory devices; memory window; Metal carbides; Multilayers; MXenes; MXene–TiO 2; Nanosheets; Oxidation; Thickness; Titanium dioxide; Transistors; Transition metals; Work functions
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.201907633

MXenes, an emerging class of 2D transition metal carbides and nitrides with the general formula Mn+1XnTx (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–TiO2 core–shell nanosheets are synthesized by deterministic control of the surface oxidation of MXene. The floating gate (multilayer MXene) and tunneling layer (TiO2) 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 (≈106), low off‐current (<1 pA), long retention (>104 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. The deterministically controlled oxidation of multilayer Ti3C2Tx MXene and the application of MXene–TiO2 core–shell nanosheets as a data‐storage medium in memory devices are demostrated. The optimized MXene nano‐floating‐gate transistor memory exhibits excellent nonvolatile memory characteristics and synaptic functions.