Tag Archives: Hewlett Packard

Memristor shakeup

New discoveries suggest that memristors do not function as was previously theorized. (For anyone who wants a memristor description, there’s this Wikipedia entry.) From an Oct. 13, 2015 posting by Alexander Hellemans for the Nanoclast blog (on the IEEE [Institute for Electrical and Electronics Engineers]), Note: Links have been removed,

What’s going to replace flash? The R&D arms of several companies including Hewlett Packard, Intel, and Samsung think the answer might be memristors (also called resistive RAM, ReRAM, or RRAM). These devices have a chance at unseating the non-volatile memory champion because, they use little energy, are very fast, and retain data without requiring power. However, new research indicates that they don’t work in quite the way we thought they do.

The fundamental mechanism at the heart of how a memristor works is something called an “imperfect point contact,” which was predicted in 1971, long before anybody had built working devices. When voltage is applied to a memristor cell, it reduces the resistance across the device. This change in resistance can be read out by applying another, smaller voltage. By inverting the voltage, the resistance of the device is returned to its initial value, that is, the stored information is erased.

Over the last decade researchers have produced two commercially promising types of memristors: electrochemical metallization memory (ECM) cells, and valence change mechanism memory (VCM) cells.

Now international research teams lead by Ilia Valov at the Peter Grünberg Institute in Jülich, Germany, report in Nature Nanotechnology and Advanced Materials that they have identified new processes that erase many of the differences between EMC and VCM cells.

Valov and coworkers in Germany, Japan, Korea, Greece, and the United States started investigating memristors that had a tantalum oxide electrolyte and an active tantalum electrode. “Our studies show that these two types of switching mechanisms in fact can be bridged, and we don’t have a purely oxygen type of switching as was believed, but that also positive [metal] ions, originating from the active electrode, are mobile,” explains Valov.

Here are links to and citations for both papers,

Graphene-Modified Interface Controls Transition from VCM to ECM Switching Modes in Ta/TaOx Based Memristive Devices by Michael Lübben, Panagiotis Karakolis, Vassilios Ioannou-Sougleridis, Pascal Normand, Pangiotis Dimitrakis, & Ilia Valov. Advanced Materials DOI: 10.1002/adma.201502574 First published: 10 September 2015

Nanoscale cation motion in TaOx, HfOx and TiOx memristive systems by Anja Wedig, Michael Luebben, Deok-Yong Cho, Marco Moors, Katharina Skaja, Vikas Rana, Tsuyoshi Hasegawa, Kiran K. Adepalli, Bilge Yildiz, Rainer Waser, & Ilia Valov. Nature Nanotechnology (2015) doi:10.1038/nnano.2015.221 Published online 28 September 2015

Both papers are behind paywalls.

Memristor, memristor! What is happening? News from the University of Michigan and HP Laboratories

Professor Wei Lu (whose work on memristors has been mentioned here a few times [an April 15, 2010 posting and an April 19, 2012 posting]) has made a discovery about memristors with significant implications (from a June 25, 2014 news item on Azonano),

In work that unmasks some of the magic behind memristors and “resistive random access memory,” or RRAM—cutting-edge computer components that combine logic and memory functions—researchers have shown that the metal particles in memristors don’t stay put as previously thought.

The findings have broad implications for the semiconductor industry and beyond. They show, for the first time, exactly how some memristors remember.

A June 24, 2014 University of Michigan news release, which originated the news item, includes Lu’s perspective on this discovery and more details about it,

“Most people have thought you can’t move metal particles in a solid material,” said Wei Lu, associate professor of electrical and computer engineering at the University of Michigan. “In a liquid and gas, it’s mobile and people understand that, but in a solid we don’t expect this behavior. This is the first time it has been shown.”

Lu, who led the project, and colleagues at U-M and the Electronic Research Centre Jülich in Germany used transmission electron microscopes to watch and record what happens to the atoms in the metal layer of their memristor when they exposed it to an electric field. The metal layer was encased in the dielectric material silicon dioxide, which is commonly used in the semiconductor industry to help route electricity.

They observed the metal atoms becoming charged ions, clustering with up to thousands of others into metal nanoparticles, and then migrating and forming a bridge between the electrodes at the opposite ends of the dielectric material.

They demonstrated this process with several metals, including silver and platinum. And depending on the materials involved and the electric current, the bridge formed in different ways.

The bridge, also called a conducting filament, stays put after the electrical power is turned off in the device. So when researchers turn the power back on, the bridge is there as a smooth pathway for current to travel along. Further, the electric field can be used to change the shape and size of the filament, or break the filament altogether, which in turn regulates the resistance of the device, or how easy current can flow through it.

Computers built with memristors would encode information in these different resistance values, which is in turn based on a different arrangement of conducting filaments.

Memristor researchers like Lu and his colleagues had theorized that the metal atoms in memristors moved, but previous results had yielded different shaped filaments and so they thought they hadn’t nailed down the underlying process.

“We succeeded in resolving the puzzle of apparently contradicting observations and in offering a predictive model accounting for materials and conditions,” said Ilia Valov, principle investigator at the Electronic Materials Research Centre Jülich. “Also the fact that we observed particle movement driven by electrochemical forces within dielectric matrix is in itself a sensation.”

The implications for this work (from the news release),

The results could lead to a new approach to chip design—one that involves using fine-tuned electrical signals to lay out integrated circuits after they’re fabricated. And it could also advance memristor technology, which promises smaller, faster, cheaper chips and computers inspired by biological brains in that they could perform many tasks at the same time.

As is becoming more common these days (from the news release),

Lu is a co-founder of Crossbar Inc., a Santa Clara, Calif.-based startup working to commercialize RRAM. Crossbar has just completed a $25 million Series C funding round.

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

Electrochemical dynamics of nanoscale metallic inclusions in dielectrics by Yuchao Yang, Peng Gao, Linze Li, Xiaoqing Pan, Stefan Tappertzhofen, ShinHyun Choi, Rainer Waser, Ilia Valov, & Wei D. Lu. Nature Communications 5, Article number: 4232 doi:10.1038/ncomms5232 Published 23 June 2014

This paper is behind a paywall.

The other party instrumental in the development and, they hope, the commercialization of memristors is HP (Hewlett Packard) Laboratories (HP Labs). Anyone familiar with this blog will likely know I have frequently covered the topic starting with an essay explaining the basics on my Nanotech Mysteries wiki (or you can check this more extensive and more recently updated entry on Wikipedia) and with subsequent entries here over the years. The most recent entry is a Jan. 9, 2014 posting which featured the then latest information on the HP Labs memristor situation (scroll down about 50% of the way). This new information is more in the nature of a new revelation of details rather than an update on its status. Sebastian Anthony’s June 11, 2014 article for extremetech.com lays out the situation plainly (Note: Links have been removed),

HP, one of the original 800lb Silicon Valley gorillas that has seen much happier days, is staking everything on a brand new computer architecture that it calls… The Machine. Judging by an early report from Bloomberg Businessweek, up to 75% of HP’s once fairly illustrious R&D division — HP Labs – are working on The Machine. As you would expect, details of what will actually make The Machine a unique proposition are hard to come by, but it sounds like HP’s groundbreaking work on memristors (pictured top) and silicon photonics will play a key role.

First things first, we’re probably not talking about a consumer computing architecture here, though it’s possible that technologies commercialized by The Machine will percolate down to desktops and laptops. Basically, HP used to be a huge player in the workstation and server markets, with its own operating system and hardware architecture, much like Sun. Over the last 10 years though, Intel’s x86 architecture has rapidly taken over, to the point where HP (and Dell and IBM) are essentially just OEM resellers of commodity x86 servers. This has driven down enterprise profit margins — and when combined with its huge stake in the diminishing PC market, you can see why HP is rather nervous about the future. The Machine, and IBM’s OpenPower initiative, are both attempts to get out from underneath Intel’s x86 monopoly.

While exact details are hard to come by, it seems The Machine is predicated on the idea that current RAM, storage, and interconnect technology can’t keep up with modern Big Data processing requirements. HP is working on two technologies that could solve both problems: Memristors could replace RAM and long-term flash storage, and silicon photonics could provide faster on- and off-motherboard buses. Memristors essentially combine the benefits of DRAM and flash storage in a single, hyper-fast, super-dense package. Silicon photonics is all about reducing optical transmission and reception to a scale that can be integrated into silicon chips (moving from electrical to optical would allow for much higher data rates and lower power consumption). Both technologies can be built using conventional fabrication techniques.

In a June 11, 2014 article by Ashlee Vance for Bloomberg Business Newsweek, the company’s CTO (Chief Technical Officer), Martin Fink provides new details,

That’s what they’re calling it at HP Labs: “the Machine.” It’s basically a brand-new type of computer architecture that HP’s engineers say will serve as a replacement for today’s designs, with a new operating system, a different type of memory, and superfast data transfer. The company says it will bring the Machine to market within the next few years or fall on its face trying. “We think we have no choice,” says Martin Fink, the chief technology officer and head of HP Labs, who is expected to unveil HP’s plans at a conference Wednesday [June 11, 2014].

In my Jan. 9, 2014 posting there’s a quote from Martin Fink stating that 2018 would be earliest date for the company’s StoreServ arrays to be packed with 100TB Memristor drives (the Machine?). The company later clarified the comment by noting that it’s very difficult to set dates for new technology arrivals.

Vance shares what could be a stirring ‘origins’ story of sorts, provided the Machine is successful,

The Machine started to take shape two years ago, after Fink was named director of HP Labs. Assessing the company’s projects, he says, made it clear that HP was developing the needed components to create a better computing system. Among its research projects: a new form of memory known as memristors; and silicon photonics, the transfer of data inside a computer using light instead of copper wires. And its researchers have worked on operating systems including Windows, Linux, HP-UX, Tru64, and NonStop.

Fink and his colleagues decided to pitch HP Chief Executive Officer Meg Whitman on the idea of assembling all this technology to form the Machine. During a two-hour presentation held a year and a half ago, they laid out how the computer might work, its benefits, and the expectation that about 75 percent of HP Labs personnel would be dedicated to this one project. “At the end, Meg turned to [Chief Financial Officer] Cathie Lesjak and said, ‘Find them more money,’” says John Sontag, the vice president of systems research at HP, who attended the meeting and is in charge of bringing the Machine to life. “People in Labs see this as a once-in-a-lifetime opportunity.”

Here is the memristor making an appearance in Vance’s article,

HP’s bet is the memristor, a nanoscale chip that Labs researchers must build and handle in full anticontamination clean-room suits. At the simplest level, the memristor consists of a grid of wires with a stack of thin layers of materials such as tantalum oxide at each intersection. When a current is applied to the wires, the materials’ resistance is altered, and this state can hold after the current is removed. At that point, the device is essentially remembering 1s or 0s depending on which state it is in, multiplying its storage capacity. HP can build these chips with traditional semiconductor equipment and expects to be able to pack unprecedented amounts of memory—enough to store huge databases of pictures, files, and data—into a computer.

New memory and networking technology requires a new operating system. Most applications written in the past 50 years have been taught to wait for data, assuming that the memory systems feeding the main computers chips are slow. Fink has assigned one team to develop the open-source Machine OS, which will assume the availability of a high-speed, constant memory store. …

Peter Bright in his June 11, 2014 article for Ars Technica opens his article with a controversial statement (Note: Links have been removed),

In 2008, scientists at HP invented a fourth fundamental component to join the resistor, capacitor, and inductor: the memristor. [emphasis mine] Theorized back in 1971, memristors showed promise in computing as they can be used to both build logic gates, the building blocks of processors, and also act as long-term storage.

Whether or not the memristor is a fourth fundamental component has been a matter of some debate as you can see in this Memristor entry (section on Memristor definition and criticism) on Wikipedia.

Bright goes on to provide a 2016 delivery date for some type of memristor-based product and additional technical insight about the Machine,

… By 2016, the company plans to have memristor-based DIMMs, which will combine the high storage densities of hard disks with the high performance of traditional DRAM.

John Sontag, vice president of HP Systems Research, said that The Machine would use “electrons for processing, photons for communication, and ions for storage.” The electrons are found in conventional silicon processors, and the ions are found in the memristors. The photons are because the company wants to use optical interconnects in the system, built using silicon photonics technology. With silicon photonics, photons are generated on, and travel through, “circuits” etched onto silicon chips, enabling conventional chip manufacturing to construct optical parts. This allows the parts of the system using photons to be tightly integrated with the parts using electrons.

The memristor story has proved to be even more fascinating than I thought in 2008 and I was already as fascinated as could be, or so I thought.

*2700th posting: new generation of hybird memristive nanodevices and an update of HP labs and its memristive products

Hard to believe this is the *2700th posting but yay! To commemorate this special occasion I’m featuring two items about memristors, work on protein-based memristors and an update of my Feb. 7, 2013 posting on the HP Labs and its promises of memristor-based products.

Michael Berger’s Dec. 16, 2013 issue of Nanowerk Spotlight focused on memristor research from bioengineers at Singapore’s Nanyang Technological University (Note: Links have been removed),

 Based on the rapid development of synthetic chemistry and bioengineering, researchers have begun to build hybrid nanostructures with various biomolecules to fulfill the functional requirements of advanced nanocircuits. Proteins already perform functions such as signalling, charge transport or storage, in all biochemical processes.

“Although the diversity of these natural molecules is vast – for instance, more than a million variants of an individual protein may be created via genetic engineering – tailoring their structures to fit the variable and complex requirements of both the biological and non-biological world is achievable by leveraging on the rapidly developing bioengineering field,” Xiaodong Chen, an Associate Professor in the School of Materials Science & Engineering at Nanyang Technological University, tells Nanowerk. “On a parallel note, bioengineering may provide an alternative approach to tune the structural and electronic properties of functional molecules leading to further development in the field of molecular electronics.”

Berger provides more context on this work by way of a 2011 Spotlight about the research (featured in my Sept. 19, 2011 posting) and then describes Chen’s latest work,

In new work, reported in a recent edition of Small (“Bioengineered Tunable Memristor Based on Protein Nanocage”) Chen and his team demonstrate a strategy for the fabrication of memristive nanodevices with stable and tunable performance by assembling ferritin monolayer inside a on-wire lithography-generated ∼12 nm gap.

Whereas the protein-based memristor devices in the previous work were fabricated from the commercial horse spleen ferritin, the new work uses the unique high iron loading capacity of Archaeoglobus fulgidus ferritin (AfFtn).

“We hypothesized that if the composition of this iron complex core can be modulated, the switching performance of the protein-based device can be controlled accordingly,” says Chen.

They found that the (tunable) iron loading in the AfFtn nanocages drastically impacts the performance of the memristive devices. The higher iron loading amount contributes to better memristive performance due to higher electrochemical activity of the ferric complex core.

This work is not going to be found in any applications for molecular devices at any time soon but it seems promising at this stage. For those who’d like more information, there’s Berger’s article or this link and a citation to the researchers’ paper,

Bioengineered Tunable Memristor Based on Protein Nanocage by Fanben Meng, Barindra Sana, Yuangang Li, Yuanjun Liu, Sierin Lim, & Xiaodong Chen. Article first published online: 19 AUG 2013 DOI: 10.1002/smll.201300810
© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall but Wiley does offer a number of viewing options at different price points.

HP Labs and its memristor-based products

Following on last year’s Feb. 7, 2013 update (scroll down about 1/2 way), it seems like another annual update is in order unfortunately, the news seems like a retread. Memristor’-based devices from HP Labs will not be launched (in the marketplace or even to show at technology shows) this year either. In fact, any sort of launch is much further in the future according to Chris Mellor’s Nov. 1, 2013 article for The Register; Note: Links have been removed),

HP has warned El Reg not to get its hopes up too high after the tech titan’s CTO Martin Fink suggested StoreServ arrays could be packed with 100TB Memristor drives come 2018.

In five years, according to Fink, DRAM and NAND scaling will hit a wall, limiting the maximum capacity of the technologies: process shrinks will come to a shuddering halt when the memories’ reliability drops off a cliff as a side effect of reducing the size of electronics on the silicon dies.

The HP answer to this scaling wall is Memristor, its flavour of resistive RAM technology that is supposed to have DRAM-like speed and better-than-NAND storage density. Fink claimed at an HP Discover event in Las Vegas that Memristor devices will be ready by the time flash NAND hits its limit in five years. He also showed off a Memristor wafer, adding that it could have a 1.5PB capacity by the end of the decade.

Fink spoke about the tech in June, but this week a HP spokesperson clarified to The Reg:

As with many other ground-breaking technologies being developed at HP Labs, HP has not yet committed to a specific product roadmap for Memristor-based products. HP does have internal milestones that are subject to change, depending on shifting market, technology and business conditions.

Every time I read about it HP Labs’ memristor-based products  they keep receding further into the future. Compare this latest announcement with what was being said at the time of my Feb.7, 2013 posting,

… Stanley Williams’ presence in the video reminded me of the memristor and an announcement (mentioned in my April 19, 2012 posting) that HP Labs would be rolling out some memristor-enabled products in 2013. Sadly, later in the year I missed this announcement, from a July 9, 2012 posting by Chris Mellor for TheRegister.co.uk,

Previously he (Stanley Williams) has said that HP and fab partner Hynix would launch a memristor product in the summer of 2013. At the Kavli do [Kavli Foundation Roundtable, June 2012], Williams said: “In terms of commercialisation, we’ll have something technologically viable by the end of next year [2014].”

To be fair, it seems HP Labs had abandoned plans for a commercial launch of memristor-based products even in 2013 but now it seems there is no roadmap of any kind.

* Corrected from ‘3000’ to ‘2700’.

Free Global STEMx (science, technology, engineering, mathematics) Education Conference online in September 2013

A notice for this conference slipped into my mailbox on Aug. 19, 2013,

We hope you will consider joining us for the Global 2013 STEMx Education Conference, the world’s first massively open online conference for educators focusing on Science, Technology, Engineering, Math, and more. The conference will be held over the course of three days, September 19-21, 2013, and will be free to attend! STEMxCon will be a highly inclusive event that will engage students and educators around the globe and will encourage primary, secondary, and tertiary (K-16) educators around the world to share and learn about innovative approaches to STEMx learning and teaching. …

Please register at http://www.stemxcon.com to attend and to be kept informed.

Usually, I’d jump to a description of the keynote speakers but I think this explanation for why they’ve added an x to STEM bears some attention (from the notice),

The Science, Technology, Engineering, and Mathematics acronym is no longer adequate, as it is missing well over 20 letters that represent key skills & disciplines. As such, x = Computer Science (CS), Computational Thinking (CT), Inquiry (I), Creativity & Innovation (CI), Global Fluency (GF), Collaboration ( C ), …and other emerging disciplines & 21st century skills.

The Council of Canadian Academies (CCA) assessment Strengthening Canada’s Research Capacity: The Gender Dimension; The Expert Panel on Women in University Research also noted that the STEM designation leaves something to be desired (my Feb. 22, 2013 posting).

Now onto the keynote speakers (from the notice),

We have a terrific set of keynote speakers for STEMxCon, including

  • Tim Bell on computer science in New Zealand,
  • Al Byers on STEM teacher learning communities at the NSTA [National Science Teachers Association],
  • Jeanne Century on STEM schools,
  • Cristin Frodella on the Google Science Fair,
  • Paloma Garcia-Lopez on the Maker Education Initiative,
  • Iris Lapinski on Apps for Good,
  • Ramsey Musallar on an inquiry-based learning cycle,
  • Ramji Raghavan on sparking curiosity and nurturing creativity, and
  • Avis Yates Rivers on inspiring the next generation in IT.

More information at http://stemxcon.com/page/2013-keynotes.

It’s still possible to respond to the call for presentation proposals, from the  ‘Call’ page,

Proposals can be submitted from May 30th – September 1st, 2013, and we will begin accepting proposals starting June 30th, 2013. We encourage you to submit your proposal as early as possible because as soon as a proposal is accepted, you are given the ability to select from the available presentation times (the time choices become increasingly limited closer to the event). You may submit more than one proposal, but we will give priority to providing as many presenters the chance to present as possible.

Your presentation proposal, once submitted, will be listed on the STEMx Conference website, with the opportunity for members of this network to view, comment on, and/or “like” your presentation proposal. This will give you and the other members of this site the chance to share ideas and to make connections before, during, and after the conference. …

Presentations should be at least 20 minutes in length, and all sessions must be completed (including Q&A) within one hour. All sessions will be held in the Blackboard Collaborate online platform (previously Elluminate/Wimba). You will be responsible for familiarizing yourself with the web conferencing platform. We will send you recorded training material, as well as provide live training sessions where you can ask questions. To practice, you can also sign up for the Collaborate trial room at http://www.WeCollaborate.com.

All presentations will be recorded and released under a Creative Commons Attribution-NonCommercial-NoDerivs License. For more information, please visit: http://creativecommons.org/licenses/by-nc-nd/3.0/). By submitting to present, you are agreeing to these terms.

Presentations must be non-commercial. Interest in commercial sponsorship or presentations should be directed to Steve Hargadon at steve@hargadon.com.

The guidelines for submissions and other pertinent details are on the Call for proposals page.

I did find some information about the organization and the entities supporting its conference efforts on the 2013 STEMx Conference Welcome! webpage (Note: Links have been removed),

STEMxCon’s founding sponsor is HP [Hewlett Packard]. As one of the world’s largest technology companies with operations in more than 170 countries, HP is helping to solve environmental and social challenges by uniting the power of people and technology. The HP Sustainability & Social Innovation team focuses on improving lives and businesses every day by focusing on the environment, health, education, and community. By bringing together the expertise of their more than 300,000 HP employees in collaboration with our partners, HP makes technology work for people in powerful ways that create a positive impact on the world.

The International Society for Technology in Education (ISTE®) is also a core conference supporter, and is the premier membership association for educators and education leaders engaged in improving learning and teaching by advancing the effective use of technology in PK–12 and teacher education. ISTE represents more than 100,000 education leaders and emerging leaders throughout the world and informs its members regarding educational issues of national and global scope.

I like the openness of their approach and the note somewhere in the submission guidelines that the language in which the presentation is being offered be mentioned suggests they’re making a big effort to attract an international audience. I wish them the best of luck.

Resistive memory from University of California Riverside (replacing flash memory in mobile devices) and Boise State University (neuron chips)

Today, (Aug. 19, 2 013)I have two items on memristors. First, Dexter Johnson provides some context for understanding why a University of California Riverside research team’s approach to creating memristors is exciting some interest in his Aug. 17, 2013 posting (Nanoclast blog on the IEEE [Institute of Electrical and Electronics Engineers] website), Note: Links have been removed,

The heralding of the memristor, or resistive memory, and the long-anticipated demise of flash memory have both been tracking on opposite trajectories with resistive memory expected to displace flash ever since the memristor was first discovered by Stanley Williams’ group at Hewlett Packard in 2008.

The memristor has been on a rapid development track ever since and has been promised to be commercially available as early as 2014, enabling 10 times greater embedded memory for mobile devices than currently available.

The obsolescence of flash memory at the hands of the latest nanotechnology has been predicted for longer than the commercial introduction of the memristor. But just at the moment it appears it’s going to reach its limits in storage capacity along comes a new way to push its capabilities to new heights, sometimes thanks to a nanomaterial like graphene.

In addition to the graphene promise, Dexter goes on to discuss another development,  which could push memory capabilities and which is mentioned in an Aug. 14, 2013 news item on ScienceDaily (and elsewhere),

A team at the University of California, Riverside Bourns College of Engineering has developed a novel way to build what many see as the next generation memory storage devices for portable electronic devices including smart phones, tablets, laptops and digital cameras.

The device is based on the principles of resistive memory [memristor], which can be used to create memory cells that are smaller, operate at a higher speed and offer more storage capacity than flash memory cells, the current industry standard. Terabytes, not gigbytes, will be the norm with resistive memory.

The key advancement in the UC Riverside research is the creation of a zinc oxide nano-island on silicon. It eliminates the need for a second element called a selector device, which is often a diode.

The Aug. 13, 2013 University of California Riverside news release by Sean Nealon, which originated the news item, further describes the limitations of flash memory and reinforces the importance of being able to eliminate a component (selector device),

Flash memory has been the standard in the electronics industry for decades. But, as flash continues to get smaller and users want higher storage capacity, it appears to reaching the end of its lifespan, Liu [Jianlin Liu, a professor of electrical engineering] said.

With that in mind, resistive memory is receiving significant attention from academia and the electronics industry because it has a simple structure, high-density integration, fast operation and long endurance.

Researchers have also found that resistive memory can be scaled down in the sub 10-nanometer scale. (A nanometer is one-billionth of a meter.) Current flash memory devices are roughly using a feature size twice as large.

Resistive memory usually has a metal-oxide-metal structure in connection with a selector device. The UC Riverside team has demonstrated a novel alternative way by forming self-assembled zinc oxide nano-islands on silicon. Using a conductive atomic force microscope, the researchers observed three operation modes from the same device structure, essentially eliminating the need for a separate selector device.

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

Multimode Resistive Switching in Single ZnO Nanoisland System by Jing Qi, Mario Olmedo, Jian-Guo Zheng, & Jianlin Liu. Scientific Reports 3, Article number: 2405 doi:10.1038/srep02405 Published 12 August 2013

This study is open access.

Meanwhile, Boise State University (Idaho, US) is celebrating a new project, CIF: Small: Realizing Chip-scale Bio-inspired Spiking Neural Networks with Monolithically Integrated Nano-scale Memristors, which was announced in an Aug. 17, 2013 news item on Azonano,

Electrical and computer engineering faculty Elisa Barney Smith, Kris Campbell and Vishal Saxena are joining forces on a project titled “CIF: Small: Realizing Chip-scale Bio-inspired Spiking Neural Networks with Monolithically Integrated Nano-scale Memristors.”

Team members are experts in machine learning (artificial intelligence), integrated circuit design and memristor devices. Funded by a three-year, $500,000 National Science Foundation grant, they have taken on the challenge of developing a new kind of computing architecture that works more like a brain than a traditional digital computer.

“By mimicking the brain’s billions of interconnections and pattern recognition capabilities, we may ultimately introduce a new paradigm in speed and power, and potentially enable systems that include the ability to learn, adapt and respond to their environment,” said Barney Smith, who is the principal investigator on the grant.

The Aug. 14, 2013 Boise State University news release by Kathleen Tuck, which originated the news item, describes the team’s focus on mimicking the brain’s capabilities ,

One of the first memristors was built in Campbell’s Boise State lab, which has the distinction of being one of only five or six labs worldwide that are up to the task.

The team’s research builds on recent work from scientists who have derived mathematical algorithms to explain the electrical interaction between brain synapses and neurons.

“By employing these models in combination with a new device technology that exhibits similar electrical response to the neural synapses, we will design entirely new computing chips that mimic how the brain processes information,” said Barney Smith.

Even better, these new chips will consume power at an order of magnitude lower than current computing processors, despite the fact that they match existing chips in physical dimensions. This will open the door for ultra low-power electronics intended for applications with scarce energy resources, such as in space, environmental sensors or biomedical implants.

Once the team has successfully built an artificial neural network, they will look to engage neurobiologists in parallel to what they are doing now. A proposal for that could be written in the coming year.

Barney Smith said they hope to send the first of the new neuron chips out for fabrication within weeks.

With the possibility that HP Labs will make its ‘memristor chips‘ commercially available in 2014 and neuron chips fabricated for the Boise State University researchers within weeks of this Aug. 19, 2013 date, it seems that memristors have been developed at a lightning fast pace. It’s been a fascinating process to observe.

Extending memristive theory

This is kind of fascinating. A German research team based at JARA (Jülich Aachen Research Alliance) is suggesting that memristive theory be extended beyond passive components in their paper about Resistive Memory Cells (ReRAM) which was recently published in Nature Communications. From the Apr. 26, 2013 news item on Azonano,

Resistive memory cells (ReRAM) are regarded as a promising solution for future generations of computer memories. They will dramatically reduce the energy consumption of modern IT systems while significantly increasing their performance.

Unlike the building blocks of conventional hard disk drives and memories, these novel memory cells are not purely passive components but must be regarded as tiny batteries. This has been demonstrated by researchers of Jülich Aachen Research Alliance (JARA), whose findings have now been published in the prestigious journal Nature Communications. The new finding radically revises the current theory and opens up possibilities for further applications. The research group has already filed a patent application for their first idea on how to improve data readout with the aid of battery voltage.

The Apr. 23, 2013 JARA news release, which originated the news item, provides some background information about data memory before going on to discuss the ReRAMs,

Conventional data memory works on the basis of electrons that are moved around and stored. However, even by atomic standards, electrons are extremely small. It is very difficult to control them, for example by means of relatively thick insulator walls, so that information will not be lost over time. This does not only limit storage density, it also costs a great deal of energy. For this reason, researchers are working feverishly all over the world on nanoelectronic components that make use of ions, i.e. charged atoms, for storing data. Ions are some thousands of times heavier that electrons and are therefore much easier to ‘hold down’. In this way, the individual storage elements can almost be reduced to atomic dimensions, which enormously improves the storage density.

Here’s how the ions behave in ReRAMs (from the news release),

In resistive switching memory cells (ReRAMs), ions behave on the nanometre scale in a similar manner to a battery. The cells have two electrodes, for example made of silver and platinum, at which the ions dissolve and then precipitate again. This changes the electrical resistance, which can be exploited for data storage. Furthermore, the reduction and oxidation processes also have another effect. They generate electric voltage. ReRAM cells are therefore not purely passive systems – they are also active electrochemical components. Consequently, they can be regarded as tiny batteries whose properties provide the key to the correct modelling and development of future data storage.

In complex experiments, the scientists from Forschungszentrum Jülich and RWTH Aachen University determined the battery voltage of typical representatives of ReRAM cells and compared them with theoretical values. This comparison revealed other properties (such as ionic resistance) that were previously neither known nor accessible. “Looking back, the presence of a battery voltage in ReRAMs is self-evident. But during the nine-month review process of the paper now published we had to do a lot of persuading, since the battery voltage in ReRAM cells can have three different basic causes, and the assignment of the correct cause is anything but trivial,” says Dr. Ilia Valov, the electrochemist in Prof. Rainer Waser’s research group.

This discovery could lead to optimizing ReRAMs and exploiting them in new applications (from the news release),

“The new findings will help to solve a central puzzle of international ReRAM research,” says Prof. Rainer Waser, deputy spokesman of the collaborative research centre SFB 917 ‘Nanoswitches’ established in 2011. In recent years, these puzzling aspects include unexplained long-term drift phenomena or systematic parameter deviations, which had been attributed to fabrication methods. “In the light of this new knowledge, it is possible to specifically optimize the design of the ReRAM cells, and it may be possible to discover new ways of exploiting the cells’ battery voltage for completely new applications, which were previously beyond the reach of technical possibilities,” adds Waser, whose group has been collaborating for years with companies such as Intel and Samsung Electronics in the field of ReRAM elements.

The part I found most interesting, given my interest in memristors, is this bit about extending the memristor theory, from the news release,

The new finding is of central significance, in particular, for the theoretical description of the memory components. To date, ReRAM cells have been described with the aid of the concept of memristors – a portmanteau word composed of “memory” and “resistor”. The theoretical concept of memristors can be traced back to Leon Chua in the 1970s. It was first applied to ReRAM cells by the IT company Hewlett-Packard in 2008. It aims at the permanent storage of information by changing the electrical resistance. The memristor theory leads to an important restriction. It is limited to passive components. “The demonstrated internal battery voltage of ReRAM elements clearly violates the mathematical construct of the memristor theory. This theory must be expanded to a whole new theory – to properly describe the ReRAM elements,” says Dr. Eike Linn, the specialist for circuit concepts in the group of authors. [emphases mine] This also places the development of all micro- and nanoelectronic chips on a completely new footing.

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

Nanobatteries in redox-based resistive switches require extension of memristor theory by I. Valov,  E. Linn, S. Tappertzhofen,  S. Schmelzer,  J. van den Hurk,  F. Lentz,  & R. Waser. Nature Communications 4, Article number: 1771 doi:10.1038/ncomms2784 Published 23 April 2013

This paper is open access (as of this writing).

Here’s a list of my 2013 postings on memristors and memristive devices,

2.5M Euros for Ireland’s John Boland and his memristive nanowires (Apr. 4, 2013 posting)

How to use a memristor to create an artificial brain (Feb. 26, 2013 posting)

CeNSE (Central Nervous System of the Earth) and billions of tiny sensors from HP plus a memristor update (Feb. 7, 2013 posting)

For anyone who cares to search the blog, there are several more.