NRAM: a disruptive carbon-nanotube resistance-change memory

Abstract

Advanced memory technology based on carbon nanotubes (CNTs) (NRAM) possesses desired properties for implementation in a host of integrated systems due to demonstrated advantages of its operation including high speed (nanotubes can switch state in picoseconds), high endurance (over a trillion), and low power (with essential zero standby power). The applicable integrated systems for NRAM have markets that will see compound annual growth rates (CAGR) of over 62% between 2018 and 2023, with an embedded systems CAGR of 115% in 2018-2023 (http://bccresearch.com/pressroom/smc/bcc-research-predicts:-nram-(finally)-to-revolutionize-computer-memory). These opportunities are helping drive the realization of a shift from silicon-based to carbon-based (NRAM) memories. NRAM is a memory cell made up of an interlocking matrix of CNTs, either touching or slightly separated, leading to low or higher resistance states respectively. The small movement of atoms, as opposed to moving electrons for traditional silicon-based memories, renders NRAM with a more robust endurance and high temperature retention/operation which, along with high speed/low power, is expected to blossom in this memory technology to be a disruptive replacement for the current status quo of DRAM (dynamic RAM), SRAM (static RAM), and NAND flash memories.

Memory technology—a primer for material scientists

“…The first publication on this concept appeared in 2000 [318]. A startup company called Nantero has pushed the concept ever since with a significant change in the cell architecture compared to the original proposal and very promising results [319]. However, the concept is mainly promoted by one startup company, which is why significantly less data is available than for the other concepts.…”

“…Additionally, the available data e.g. from reference [319] uses very large structures to show very good results, but the scalability remains unclear. Nonetheless, the technology was discussed as a potential DRAM replacement [320], or in our terminology an NV-RAM, which is probably still the toughest goal for any emerging memory technology.…”

Atomic layer engineering on resistive switching in sub-4 nm AlN resistive random access memory devices

“…2–4 A variety of metal oxides (such as HfO 2 , ZrO 2 , Ta 2 O 5 , and TiO 2 ) have been used in RRAM devices based on conductive filaments. 5,6 However, the local heating effect produces uncontrolled conductive filaments, resulting in challenges including switching current overshoot, non-uniformity, and device-to-device variation. 7,8 On the other hand, aluminum nitride (AlN) is a promising material because it has several favorable properties such as a wide band gap, high thermal stability, a high thermal conductivity of up to 285 W m −1 K −1 , and good chemical stability.…”

Atomistic Modeling of the Electrical Conductivity of Single‐Walled Carbon Nanotube Junctions

“…It has resulted in their use in a wide range of applications, including wearable, transparent and flexible electronics, gas sensing, catalysis, resistive switching, space exploration, and more. [2,[4][5][6][7][8][9][10][11][12][13] In many of these applications, a CNT network is fabricated as a film, synonymously referred to as a fabric. An example of the structure of a disordered film is shown in Figure 2 in the study by Lyons et al [14] Due to the complexity of the fabric structure, the desirable properties of a single nanotube do not directly translate into the characteristics of the CNT film as a whole.…”