Subnanosecond flash memory enabled by 2D-enhanced hot-carrier injection.

Xiang, Yutong; Wang, Chong; Liu, Chunsen; Wang, Tanjun; Jiang, Yongbo; Wang, Yang; Wang, Shuiyuan; Zhou, Peng · Nature · 2025

basic_science · Level V

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Abstract

The pursuit of non-volatile memory with program speeds below one nanosecond, beyond the capabilities of non-volatile flash and high-speed volatile static random-access memory, remains a longstanding challenge in the field of memory technology<sup>1</sup>. Utilizing fundamental physics innovation enabled by advanced materials, series of emerging memories<sup>2-5</sup> are being developed to overcome the speed bottleneck of non-volatile memory. As the most extensively applied non-volatile memory, the speed of flash is limited by the low efficiency of the electric-field-assisted program, with reported speeds<sup>6-10</sup> much slower than sub-one nanosecond. Here we report a two-dimensional Dirac graphene-channel flash memory based on a two-dimensional-enhanced hot-carrier-injection mechanism, supporting both electron and hole injection. The Dirac channel flash shows a program speed of 400 picoseconds, non-volatile storage and robust endurance over 5.5 × 10<sup>6</sup> cycles. Our results confirm that the thin-body channel can optimize the horizontal electric-field (E<sub>y</sub>) distribution, and the improved E<sub>y</sub>-assisted program efficiency increases the injection current to 60.4 pA μm<sup>-1</sup> at |V<sub>DS</sub>| = 3.7 V. We also find that the two-dimensional semiconductor tungsten diselenide has two-dimensional-enhanced hot-hole injection, but with different injection behaviour. This work demonstrates that the speed of non-volatile flash memory can exceed that of the fastest volatile static random-access memory with the same channel length.