Tag Archives: MoSe2

From the memristor to the atomristor?

I’m going to let Michael Berger explain the memristor (from Berger’s Jan. 2, 2017 Nanowerk Spotlight article),

In trying to bring brain-like (neuromorphic) computing closer to reality, researchers have been working on the development of memory resistors, or memristors, which are resistors in a circuit that ‘remember’ their state even if you lose power.

Today, most computers use random access memory (RAM), which moves very quickly as a user works but does not retain unsaved data if power is lost. Flash drives, on the other hand, store information when they are not powered but work much slower. Memristors could provide a memory that is the best of both worlds: fast and reliable.

He goes on to discuss a team at the University of Texas at Austin’s work on creating an extraordinarily thin memristor: an atomristor,

he team’s work features the thinnest memory devices and it appears to be a universal effect available in all semiconducting 2D monolayers.

The scientists explain that the unexpected discovery of nonvolatile resistance switching (NVRS) in monolayer transitional metal dichalcogenides (MoS2, MoSe2, WS2, WSe2) is likely due to the inherent layered crystalline nature that produces sharp interfaces and clean tunnel barriers. This prevents excessive leakage and affords stable phenomenon so that NVRS can be used for existing memory and computing applications.

“Our work opens up a new field of research in exploiting defects at the atomic scale, and can advance existing applications such as future generation high density storage, and 3D cross-bar networks for neuromorphic memory computing,” notes Akinwande [Deji Akinwande, an Associate Professor at the University of Texas at Austin]. “We also discovered a completely new application, which is non-volatile switching for radio-frequency (RF) communication systems. This is a rapidly emerging field because of the massive growth in wireless technologies and the need for very low-power switches. Our devices consume no static power, an important feature for battery life in mobile communication systems.”

Here’s a link to and a citation for the Akinwande team’s paper,

Atomristor: Nonvolatile Resistance Switching in Atomic Sheets of Transition Metal Dichalcogenides by Ruijing Ge, Xiaohan Wu, Myungsoo Kim, Jianping Shi, Sushant Sonde, Li Tao, Yanfeng Zhang, Jack C. Lee, and Deji Akinwande. Nano Lett., Article ASAP DOI: 10.1021/acs.nanolett.7b04342 Publication Date (Web): December 13, 2017

Copyright © 2017 American Chemical Society

This paper appears to be open access.

ETA January 23, 2018: There’s another account of the atomristor in Samuel K. Moore’s January 23, 2018 posting on the Nanoclast blog (on the IEEE [Institute of Electrical and Electronics Engineers] website).

2D-nanocellulose and electricity

The 2D trend seems to have swept into the world of nanocellulose materials. An Oct. 13, 2016 news item on Nanowerk describes work in the field piezoelectronics as driven by 2D nanocellulose materials (Note: A link has been removed),

Researchers from ICN2 [Catalan Institute of Nanoscience and Nanotechnology] Phononic and Photonic Nanostructures Group publish in Scientific Reports (“Orthotropic Piezoelectricity in 2D Nanocellulose”) findings providing the basis for new electromechanical designs using 2D-nanocellulose. In a longer-term perspective, the reinterpretation of electrical features for hydrogen bonds here introduced could pave the way in the understanding of life-essential molecules and events.

An Oct. 11, 2016 ICN2 press release, which originated the news item, provides more information about this area of research,

In the next coming years nanocellulose (NC) would attract lot of attention from industrial researchers (market value is estimated to be 530 M$ worldwide by 2020)(1). The process of development and functionalization of NC materials is being promising because of their well-known unique optomechanical features and green nature. However, there is still a niche for applications based on NC electric-response. In this scenario, the results published in Scientific Reports with the participation of ICN2 researchers, would set up foundations for new strategies intended to drive novel applications based on 2D-NC with a predicted piezoelectric-response ~ pm V-1. This result could rank NC at the level of currently used bulk piezoelectrics like α-quartz and most recent 2D materials like MoSe2 or doped graphene. The first author of the article is Dr Yamila García, and the last one ICREA Research prof. Dr Clivia M. Sotomayor-Torres, Group leader of the ICN2 Phononic and Photonic Nanostructures Group.

“We are too big” (2). It is one of the main limitations to do nanotechnology as Richard Feynman pointed out in 1959. As a contribution in paving the way to overcome this restriction, it is introduced a theoretical framework for the investigation of electric field profiles with interatomic resolution and thus to understand the fundamentals of the electromechanical coupling at the nanoscale. Remarkably, the mean-field descriptor obtained with the methodology described in the manuscript would also complete the latest definition of hydrogen bonds stated by IUPAC since it is the first effective approach in quantifying the electrical nature of such interactions.

An “atom by atom” (2) understanding of electrical forces managing directional bonds is needed if we plan to engineer materials by means of highly selected nanoscale oriented mechanisms. So then, deepening on the understanding of 2D-NC as a piezoelectric system managed by electroactive and well-distinguishable HB  could facilitate new openings for nanotechnologies  community intended to progress on NC applications, i.e. straightforwardly introducing electronic-base sensing and actuating applications. Looking to the future, areas like molecular biology or genetic engineering would be benefited by the new contributions on the understanding of electrical forces within life-essential hydrogen bonds.

(1) Nanocellulose (Nano-crystalline Cellulose, Nano-fibrillated Cellulose and Bacterial Nanocellulose) Market for Composites, Oil & Gas, Paper Processing, Paints & Coatings, and Other Applications: Global Industry Perspective, Comprehensive Analysis, Size, Share, Growth, Segment, Trends and Forecast, 2015 – 2021.

(2) “The principles of physics, as far as I can see, do not speak against the possibility of manoeuvring things atom by atom. It is not an attempt to violate any laws; it is something, in principle, that can be done; but in practice, it has not been done because we are too big.” Richard Feynman, 1959

Here’s a link to and a citation for the paper,

Orthotropic Piezoelectricity in 2D Nanocellulose by Y. García, Yasser B. Ruiz-Blanco, Yovani Marrero-Ponce & C. M. Sotomayor-Torres. Scientific Reports 6, Article number: 34616 (2016) doi:10.1038/srep34616 Published online: 06 October 2016

This paper is open access.