N1005 IBM Research: nature communications

Making Memory with Carbon

<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgOkwx8dgZjEq2tT0d2JMt66-5m-lAMSfRN8mgil7BTzR-6LqGyHRX27dBcSBIBlVF2DBgrifG8kfqup1P3BlTl3Kt4bJbgZvOs3wzd8OpLYxEHP84nHL6gQcSj_iH7VZJ-2kQwJxbJbt0/s1600/ncomms9600-f3.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgOkwx8dgZjEq2tT0d2JMt66-5m-lAMSfRN8mgil7BTzR-6LqGyHRX27dBcSBIBlVF2DBgrifG8kfqup1P3BlTl3Kt4bJbgZvOs3wzd8OpLYxEHP84nHL6gQcSj_iH7VZJ-2kQwJxbJbt0/s320/ncomms9600-f3.jpg" width="271" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">    <span style="font-family: AdvOTcb88df00; font-size: 8pt;">Memory devices based on a-CO</span><span style="font-family: 'AdvOTe75a9404.I'; font-size: 6pt; vertical-align: -1pt;">x</span><span style="font-family: AdvOTcb88df00; font-size: 8pt;">.  Credit: Nature Comms</span></td></tr></tbody></table><div style="border: 0px; font-family: Arial, sans-serif; outline: 0px; padding: 6px 0px; vertical-align: baseline;"><i><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;">Memory that constitutes resistance as a state variable encompasses a broad range of materials and switching mechanisms</span></i><br /><br /><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;">Of these memory technologies, some, namely magnetic random access memory (MRAM), phase-change memory (PCM) and reduction/oxidation (redox) memories, have received more attention from the scientific community and the semiconductor industry and are thus in a more advanced state of research and/or development.</span></div><div style="border: 0px; font-family: Arial, sans-serif; outline: 0px; padding: 6px 0px; vertical-align: baseline;"><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;">At IBM Research – Zurich, we are pursuing yet another resistive memory concept based on carbon. Carbon-based memory could be a significant complement to the rapid advances in carbon-based nano-electronics. This could pave the way for potential all-carbon computing devices of the future. </span></div><div style="border: 0px; font-family: Arial, sans-serif; outline: 0px; padding: 6px 0px; vertical-align: baseline;"><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;">The elemental nature of carbon would enable a carbon-based memory to be scaled down to very small feature sizes and to be immune to compositional changes that typically plague alternate multi-elemental non-volatile memory materials.</span><br /><a name="more"></a><br /><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;">In addition, the high resilience of carbon to a variety of external stimuli would ensure robustness and endurance of such a carbon-based memory.</span></div><div style="border: 0px; font-family: Arial, sans-serif; outline: 0px; padding: 6px 0px; vertical-align: baseline;"><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;">Today, a team of scientists based in Switzerland published a significant milestone in the prestigious peer-review journal <i><a href="http://www.nature.com/ncomms/2015/151023/ncomms9600/abs/ncomms9600.html">Nature Communications</a> </i>on the development of carbon memory. I interviewed three of the paper's authors to gain some further insight on their research.</span></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjgjTOCltMcWCAgOILiPtAfDtM_BumfTng_3gIyfaUUQwjMC5msWYwUf61bzv0nX9w-tQ0O1xZeK_Rfk-ABSFYGnBMg1surI0fIU1NhYJH7C-azoX5_huFkrcSJASRhvuAgqSzqXi_U5Vc/s1600/Unknown.jpeg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjgjTOCltMcWCAgOILiPtAfDtM_BumfTng_3gIyfaUUQwjMC5msWYwUf61bzv0nX9w-tQ0O1xZeK_Rfk-ABSFYGnBMg1surI0fIU1NhYJH7C-azoX5_huFkrcSJASRhvuAgqSzqXi_U5Vc/s1600/Unknown.jpeg" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Claudia Santini</td></tr></tbody></table><div class="MsoNormal" style="margin-bottom: 0.0001pt; text-align: center;"><br /></div><div class="MsoNormal" style="margin-bottom: 0.0001pt;"><b><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;">You compare oxygenated amorphous carbon with graphite oxide in the opening abstract of the paper. Why?</span></b><br /><br /><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;"><a href="https://ch.linkedin.com/in/claudiasantini">Claudia Santini</a>: <i>Graphite and graphene oxide have been widely investigated in the past years for resistive memory applications.</i></span><br /><br /><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;"><i>However, their performance fell short of the expectations and, moreover, the fabrication methods of these materials are somehow unreliable and do not allow properly controlling their properties on wafer-scale.</i></span></div><div class="MsoNormal" style="margin-bottom: 0.0001pt;"><br /><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;"><i>This is a clear disadvantage for electronics applications. On the other hand, in our work we demonstrate that oxygenated amorphous carbon, which is a material made of carbon and oxygen like graphite/graphene oxide, can be produced by a much simpler method, its properties can be controlled on a wafer scale and outperforms graphite/graphene oxide for resistive memory applications.</i></span><span style="font-family: Helv, sans-serif;"><span style="font-size: large;"><b><br /></b></span></span></div><div class="MsoNormal" style="margin-bottom: 0.0001pt;"><br /><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;"><b>What inspired the use of oxygenated amorphous carbon?</b></span></div><div class="MsoNormal" style="margin-bottom: 0.0001pt;"><br /></div><div class="MsoNormal" style="margin-bottom: 0.0001pt;"><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;"><i>CS: A relatively simple idea. Amorphous carbon memories have been investigated in the latest years by some research groups including the group working with <a href="http://researcher.watson.ibm.com/researcher/view.php?person=zurich-ele">Evangelos Eleftheriou</a> at IBM. These memories have always shown limited endurance due to the difficulty to break the conductive carbon filaments that are thought to be responsible for the low resistance state.</i></span><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;"><i> </i></span><br /><br /><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;"><i>As it is known that carbon-based materials break down by Joule heating at much lower current densities when exposed to oxygen, I thought that the addition of oxygen as a dopant to carbon-based memories could facilitate the breaking of the carbon filaments and improve the memory endurance.</i></span><br /><br /><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;"><i>This was correct and we were able to demonstrate endurance higher than 10</i></span><i><sup style="font-family: Helv, sans-serif;">4</sup><span style="font-family: Helv, sans-serif;"> cycles without current control devices. Of course, the switching mechanism we finally demonstrated was more complex than our initial idea, but the general concept was correct.</span></i></div><div class="MsoNormal" style="margin-bottom: 0.0001pt;"><br /></div><div class="MsoNormal" style="margin-bottom: 0.0001pt;"><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;"><b>This question is for <a href="http://researcher.watson.ibm.com/researcher/view.php?person=zurich-ASE">Abu Sebastian</a> and <a href="http://researcher.ibm.com/researcher/view.php?person=zurich-WKO">Wabe Koelmans</a>: How would you compare oxygenated amorphous carbon with your recent paper on <a href="http://ibmresearchnews.blogspot.ch/2015/09/eureka-moments-lead-to-radical-new.html">Projected Memory</a>?</b></span></div><div class="MsoNormal" style="margin-bottom: 0.0001pt;"><br /></div><div class="MsoNormal" style="margin-bottom: 0.0001pt;"><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjeN58vzFCN6HgaCRNPFBFctm1qBA7DBP9LS7LXQIM2vT4GrLerN8UvCybC-nH1iqj8kMlqJeRfyUu9DHB5P1kX2_dxr9IiNmE5lz5Ndf2p19N9aIIN9oByaS1uKkMnRnqZwX8ZJr2K47U/s1600/naturecoms.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="236" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjeN58vzFCN6HgaCRNPFBFctm1qBA7DBP9LS7LXQIM2vT4GrLerN8UvCybC-nH1iqj8kMlqJeRfyUu9DHB5P1kX2_dxr9IiNmE5lz5Ndf2p19N9aIIN9oByaS1uKkMnRnqZwX8ZJr2K47U/s320/naturecoms.jpg" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><span style="font-family: AdvOTcb88df00; font-size: 8pt;">Comparison of the fabrication methods of GO and a-CO</span><span style="font-family: 'AdvOTe75a9404.I'; font-size: 6pt; vertical-align: -1pt;">x</span><span style="font-family: AdvOTcb88df00; font-size: 8pt;">. <br />Credit: Nature Communications </span></td></tr></tbody></table><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;">Abu Sebastian: <i>Both of them are non-volatile memory (NVM) candidates. In both cases we use resistance as the state variable to store information.</i> </span><br /><br /><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;">Projected memory is a radical rethink of a phase change memory device where we mitigate or eliminated several drawbacks of conventional phase change memory technology.<i> </i></span><br /><br /><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;"><i>PCM is arguably the most advanced NVM technology and projected PCM will give significant impetus to that.  Compared to phase change memory, carbon-based memory is at its infancy. But, carbon-based memory has some unique advantages.</i> </span></div><div class="MsoNormal" style="margin-bottom: 0.0001pt;"><br /><i><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;">For example, it uses a very common element as the memory material, could possibly scale to very small dimensions, can integrate seamlessly with other carbon-based electronic devices such as logic devices and interconnects. Hence in some applications, carbon-based memory and oxygenated carbon memory in particular could be much better suited.</span></i><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;"><b> </b></span><br /><br /><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;"><b>What was the biggest challenge?</b></span></div><div class="MsoNormal" style="margin-bottom: 0.0001pt;"><br /></div><div class="MsoNormal" style="margin-bottom: 0.0001pt;"><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;"><i>CS: It is not obvious to mix carbon and oxygen and make a memory out of it, which needs to withstand thousands switching cycles and it took some time before being able to convince ourselves that this could work.</i></span><br /><br /><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;"><i>But the biggest technical challenges were to produce the material and assess the reproducibility of the process and to study and understand the switching mechanism in oxygenated amorphous carbon memories.</i></span><br /><br /><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;"><i>Generally, the switching mechanism in resistive memories is an object of a long debate. The difficulty to study this mechanism comes from the fact that the switching occurs at sub-nanometer scale and it is very challenging to visualize and analyze. Thanks to a careful electrical characterization and a detailed microscopy and spectroscopy analysis we have been able to shed some light on it.</i> </span><br /><br /><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;">Wabe Koelmans: <i>Inherent variability in resistive switching devices (cell-to-cell and cycle-to-cycle).</i><b> </b></span><br /><br /><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;"><b>When do you think carbon-based electronics will enter the market?</b></span></div><div class="MsoNormal" style="margin-bottom: 0.0001pt;"><br /><i><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;">WK: There is a company called <a href="http://nantero.com/">Nantero</a> working towards a commercial memory product based on carbon as a switching material. It is unclear what their timeline is for a commercial product. As of now, there are no commercial carbon-based memory chips available.</span></i></div><div class="MsoNormal" style="margin-bottom: 0.0001pt;"><br /></div><div class="MsoNormal" style="margin-bottom: 0.0001pt;"><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;"><i>CS: Carbon-based electronics has driven a lot of interest in research in the latest years. Several electronics devices based on carbon allotropes have been demonstrated: interconnects, transistors, memories. As it was stated about one year ago by one IBM colleague, <a href="http://ibmresearchnews.blogspot.ch/2012/10/carbon-nanotubes-to-keep-up-with-moores.html">Wilfried Haensch</a>, according to the semiconductor industry’s roadmap, transistors will need to have features as small as 5 nm already in 2020 and this is when carbon is expected and will have to replace traditional silicon electronics.</i><b> </b></span><br /><br /><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;"><b>Claudia, you recently joined a new company. Are you continuing this research?</b></span><br /><br /></div><i><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;">CS: Not exactly. Optotune is a company working in the field of deformable optics so we investigate new polymer and carbon based materials for optical rather than electronics applications. Very soon we will start working on a new challenging and interdisciplinary project where an interesting mixture of MEMS, polymer and biomedical technologies will be developed to launch a new product.</span></i><br /><br /><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;"><i>Based on carbon? It can be, but you will know more about it in the future.</i><i><span style="font-family: Helvetica Neue, Arial, Helvetica, sans-serif;"> </span></i></span><br /><br /><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;"><i><span style="font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">Oxygenated amorphous carbon for resistive memory applications, Claudia A. Santini, Abu Sebastian, Chiara Marchiori, Vara Prasad Jonnalagadda, Laurent Dellmann, Wabe W. Koelmans, Marta D. Rossell, Christophe P. Rossel& Evangelos Eleftheriou, <span style="color: #333333; text-transform: capitalize;">Nature Communications, </span>6<span style="color: #333333;">, </span><span style="color: #333333;">Article number: </span><span style="color: #333333;">8600,</span><span style="color: #333333;">doi:10.1038/ncomms9600</span> </span></i></span><br /><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;"><span style="font-family: "HelvNeue Light for IBM",sans-serif; font-size: 13.0pt; line-height: 107%;"></span></span>

Memory devices based on a-CO x . Credit: Nature Comms Memory that constitutes resistance as a state variable encompasses a broad range...

Eureka Moments Lead to Radical New Memory Design

3:46 AM N1000 0

<span style="font-size: large;"><br /></span><div class="MsoNormal"><b style="mso-bidi-font-weight: normal;"><span style="font-family: Helvetica Neue, Arial, Helvetica, sans-serif; font-size: large; line-height: 107%;"></span></b></div><div class="MsoNormal"><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="https://farm6.staticflickr.com/5722/21114532851_8505903b81_n.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><span style="font-size: large;"><img border="0" src="https://farm6.staticflickr.com/5722/21114532851_8505903b81_n.jpg" /></span></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><span style="font-size: large;">Koelmans and Sebastian in the lab where the </span><br /><span style="font-size: large;">new memory design was developed</span></td></tr></tbody></table><span style="font-size: large;"><span style="font-family: 'Helvetica Neue';">IBM researcher </span><span lang="DE"><a href="http://researcher.ibm.com/researcher/view.php?person=zurich-WKO"><span class="Hyperlink0"><span lang="EN-US" style="font-family: 'Helvetica Neue';">Wabe Koelmans</span></span></a></span><span style="font-family: 'Helvetica Neue';"> had the first significant eureka moment of his young, promising career on Saturday, 14 December 2013. </span><span style="font-family: 'Helvetica Neue';"><o:p></o:p></span></span></div><div class="Default"><span style="font-size: large;"><br /></span></div><div class="Default"><span style="font-family: 'Helvetica Neue'; font-size: large;">The Dutch scientist is focused on emerging memory technologies based on what are known as <a href="http://www.research.ibm.com/labs/zurich/sto/pcm/">phase change materials</a>. Such materials can be used to store data quickly, simply by applying electrical pulses to the material, which is sandwiched between two metal electrodes.</span><br /><span style="font-size: large;"><span style="font-family: 'Helvetica Neue';"></span></span><a name="more"></a><span style="font-size: large;"><br /></span></div><div class="Default"><span style="font-size: large;"><span style="font-family: 'Helvetica Neue';">Koelmans started his experiment the prior evening at IBM</span><span style="font-family: 'Helvetica Neue';">’</span><span style="font-family: 'Helvetica Neue';">s Zurich Lab and then went home for the night to monitor the results from the comfort of his apartment. By Saturday he and his colleague </span><span lang="DE"><a href="http://researcher.ibm.com/researcher/view.php?person=zurich-ASE"><span class="Hyperlink0"><span lang="EN-US" style="font-family: 'Helvetica Neue';">Abu Sebastian</span></span></a></span><span style="font-family: 'Helvetica Neue';">, were already seeing significant progress.</span><span style="font-family: 'Helvetica Neue';"><o:p></o:p></span></span></div><div class="Default"><span style="font-size: large;"><br /></span></div><div class="Default"><span style="font-size: large;"><span style="font-family: 'Helvetica Neue';">After Koelmans made a small tweak to the experiment they exchanged some messages, and similar to waiting for a movie to finish downloading, they anxiously stared at their screens and waited.</span><span style="font-family: 'Helvetica Neue';"><o:p></o:p></span></span></div><div class="Default"><span style="font-size: large;"><br /></span></div><div class="Default"><span style="font-size: large;"><span style="font-family: 'Helvetica Neue';">“</span><span style="font-family: 'Helvetica Neue';">It was extremely addictive to check the experiment</span><span style="font-family: 'Helvetica Neue';">’</span><span style="font-family: 'Helvetica Neue';">s progress, so we were both very excited and logging in regularly. I ran over 60 experiments, each taking half an hour, in that weekend, but it was worth it,</span><span style="font-family: 'Helvetica Neue';">”</span> <span style="font-family: 'Helvetica Neue';">said Koelmans.</span><span style="font-family: 'Helvetica Neue';"><o:p></o:p></span></span></div><div class="Default"><span style="font-size: large;"><br /></span></div><div class="Default"><span style="font-size: large;"><span style="font-family: 'Helvetica Neue';">By Sunday morning, with a cup of coffee in hand, Koelmans saw the remarkable </span><span style="font-family: 'Arial Unicode MS';">—</span> <span style="font-family: 'Helvetica Neue';">drift was virtually non-existent. The significance of this requires a bit of explaining.</span><span style="font-family: 'Helvetica Neue';"><o:p></o:p></span></span></div><div class="Default"><span style="font-size: large;"><br /></span></div><div class="Default"><span style="font-size: large;"><b><span style="font-family: 'Helvetica Neue';">An Introduction to Drift</span></b><b><span style="font-family: 'Helvetica Neue';"><o:p></o:p></span></b></span></div><div class="Default"><span style="font-size: large;"><br /></span></div><div class="Default"><span style="font-size: large;"><span style="font-family: 'Helvetica Neue';">Phase change memory (PCM) devices have been investigated since the early 1970s and in the past 12 months IBM scientists have made tremendous progress with this technology publishing a number of milestone papers which demonstrate multiple bits per cell, making the technology extremely competitive with Flash.</span><span style="font-family: 'Helvetica Neue';"><o:p></o:p></span></span></div><div class="Default"><span style="font-size: large;"><br /></span></div><div class="Default"><span style="font-size: large;"><span lang="NL" style="font-family: 'Helvetica Neue';">But PCM doesn</span><span lang="FR" style="font-family: 'Helvetica Neue';">’</span><span style="font-family: 'Helvetica Neue';">t come without some drawbacks<span style="font-family: 'Helvetica Neue';"> </span></span><span style="font-family: 'Helvetica Neue';"><span style="font-family: 'Helvetica Neue';"><span style="font-family: 'Arial Unicode MS';">—</span> </span> a primary culprit being resistance drift. Drift is the change in resistance of the stored levels over time. Essentially the data moves causing your text document or your photo to eventually become corrupted and unusable </span><span style="font-family: 'Arial Unicode MS';">—</span> <span style="font-family: 'Helvetica Neue';">a very bad characteristic for a storage technology.</span><span style="font-family: 'Helvetica Neue';"><o:p></o:p></span></span></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgWEzXJXMBXZBnHl4ZFdlyqsDXBvBx0vmSp7YbAus-6jWcTJNVzGkHltRYHVBb1GYO3o_nBVImYMsFj9GREAjtkRbpOG6tIZz9cb-uyQqFwO47zPhUG1e6H2K4JF09t7rgTobKBfkimj40/s1600/paper.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><span style="font-size: large;"><img border="0" height="196" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgWEzXJXMBXZBnHl4ZFdlyqsDXBvBx0vmSp7YbAus-6jWcTJNVzGkHltRYHVBb1GYO3o_nBVImYMsFj9GREAjtkRbpOG6tIZz9cb-uyQqFwO47zPhUG1e6H2K4JF09t7rgTobKBfkimj40/s320/paper.jpg" width="320" /></span></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><span style="font-size: large;">    <i style="font-family: AdvOTea1a7398;">Fig B: </i><span style="font-family: AdvOTea1a7398;">The desired </span><span style="font-family: 'AdvOT9bd21c25.I';">I</span><span style="font-family: AdvOTea1a7398;">–</span><span style="font-family: 'AdvOT9bd21c25.I';">V </span><span style="font-family: AdvOTea1a7398;">characteristics corresponding to the </span></span><br /><span style="font-family: AdvOTea1a7398; font-size: large;">phase-change and projection segments are shown schematically <br />Credit: Nature Communications  </span></td></tr></tbody></table><div class="Default"><span style="font-size: large;"><br /></span></div><div class="Default"><span style="font-size: large;"><span style="font-family: 'Helvetica Neue';">A significant breakthrough to eliminate drift came a couple of years back when IBM scientists from Zurich and Yorktown Heights, NY proposed a novel device concept where the </span><span style="font-family: 'Helvetica Neue';">physical mechanism of writing is decoupled from the read process. To use an analogy, during the write cycle the electric pulse goes straight down through the material like water washing over a boulder in the middle of a river. But as in <i>figure B</i> during the read, the pulse goes around the material, or the boulder, decoupling the write and the read. This allows storing information without suffering from the drift that normally comes with it. <o:p></o:p></span></span></div><div class="Default"><span style="font-size: large;"><br /></span></div><div class="Default"><span style="font-size: large;"><span style="font-family: 'Helvetica Neue';">Patents for these inventions are currently pending or have been assigned including </span><span lang="DE"><a href="http://patents.justia.com/patent/9087987"><span lang="EN-US" style="font-family: 'Helvetica Neue';">Phase-change Memory Cells</span></a></span><span class="MsoHyperlink"><span style="font-family: 'Helvetica Neue';"> (2015)</span></span><span style="font-family: 'Helvetica Neue';">, </span><span lang="DE"><a href="http://patents.justia.com/patent/20150003144"><span lang="EN-US" style="font-family: 'Helvetica Neue';">Resistive Random-Access Memory Cells</span></a></span><span style="font-family: 'Helvetica Neue';"> and </span><span lang="DE"><a href="http://patents.justia.com/patent/20140369114"><span lang="EN-US" style="font-family: 'Helvetica Neue';">Phase-Change Memory Cells</span></a></span><span class="MsoHyperlink"><span style="font-family: 'Helvetica Neue';"> (2014)</span></span><span style="font-family: 'Helvetica Neue';">, see also </span><span lang="DE"><a href="http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6724727"><span lang="EN-US" style="font-family: 'Helvetica Neue';">IEDM 2013</span></a></span><span style="font-family: 'Helvetica Neue';">.</span><span style="font-family: 'Helvetica Neue';"><o:p></o:p></span></span></div><div class="Default"><span style="font-size: large;"><br /></span></div><div class="Default"><span style="font-size: large;"><span style="font-family: 'Arial Unicode MS';">“</span><span style="font-family: 'Helvetica Neue';">Over the years, IBM scientists have developed powerful techniques mostly based on read/write methodology and signal processing to counter resistance drift in order to facilitate multi-bit storage<span style="font-family: 'Helvetica Neue';">," </span></span><span style="font-family: 'Helvetica Neue';"><span style="font-family: 'Helvetica Neue';"><span style="font-family: 'Helvetica Neue';">said Abu Sebastian, one of the IBM co-inventors of the concept comments</span>.</span> "</span><span style="font-family: 'Helvetica Neue';">However, a device-level solution with substantially lower drift will further improve the error-rate performance and could enable the storage of a higher number of bits per device using the same techniques.”</span></span><br /><span style="font-size: large;"><span style="font-family: 'Helvetica Neue';"><br /></span>               </span><br /><div class="Default"><span style="font-family: 'Helvetica Neue'; font-size: large;">Despite the promise of the concept, a physical realization of such a device with a conclusive experimental demonstration of all its benefits was still missing.<o:p></o:p></span></div></div><div class="Default"><span style="font-size: large;"><br /></span></div><div class="Default"><span style="font-size: large;"><b><span style="font-family: 'Helvetica Neue';">Eureka 2.0</span></b><b><span style="font-family: 'Helvetica Neue';"><o:p></o:p></span></b></span></div><div class="Default"><span style="font-size: large;"><br /></span></div><div class="Default"><div class="Default"><span style="font-family: 'Helvetica Neue'; font-size: large;">During a period of eight months, Koelmans and his colleagues continued optimizing the design and materials to achieve fast write speeds and high endurance, attributes that make PCM a compelling memory candidate for high-throughput applications in the cloud.<o:p></o:p></span></div><div class="Default"><span style="font-size: large;"><br /></span></div><div class="Default"><span style="font-size: large;"><span style="font-family: 'Helvetica Neue';">Then came Monday, March 30, 2015. </span><span style="font-family: 'Helvetica Neue';">On this fateful spring day, Koelmans had his second significant eureka moment: near e</span><span style="font-family: 'Helvetica Neue';">limination of noise. </span><span style="font-family: 'Helvetica Neue';"><o:p></o:p></span></span></div><div class="Default"><span style="font-size: large;"><br /></span></div><div class="Default"><span style="font-family: 'Helvetica Neue'; font-size: large;">In PCM devices, besides drift, the resistance levels also experience random fluctuations. This low-frequency noise (1/f) behavior is a nightmare for multi-level storage. Drift having been dealt with, this noise is arguably the second largest challenge that limits the number of bits one could store in a single PCM device. Koelmans observed almost complete elimination of this 1/f noise in these devices.<o:p></o:p></span></div><div class="Default"><span style="font-size: large;"><br /></span></div>                    <br /><div class="Default"><span style="font-size: large;"><span style="font-family: 'Arial Unicode MS';">“</span><span style="font-family: 'Helvetica Neue';">It</span><span style="font-family: 'Arial Unicode MS';">’</span><span style="font-family: 'Helvetica Neue';">s easy to focus on the near-elimination of resistance drift, but this is only one of the benefits. The two others: much reduced 1/f noise and much reduced - and predictable - temperature dependence are also very important. In the end, you need a stable signal (resistance) over time and temperature and a good signal-to-noise ratio to facilitate multi-level PCM,</span><span style="font-family: 'Arial Unicode MS';">”</span><span style="font-family: 'Helvetica Neue';"> said Koelmans.<o:p></o:p></span></span></div></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgbJjLdMiC2VvH7WyraiSH1gyFMdbYO0gAZhbXJf84IyF5E0bSdHA6uYahQfwkVmqb_HZYBNRmOTbLAA_o0503pTxY0s1ztDEr6rXaJj_n4IOfEwJL0BOqCStHmKHdq3vKCsw9ZLOVzsiA/s1600/PCM.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><span style="font-size: large;"><img border="0" height="196" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgbJjLdMiC2VvH7WyraiSH1gyFMdbYO0gAZhbXJf84IyF5E0bSdHA6uYahQfwkVmqb_HZYBNRmOTbLAA_o0503pTxY0s1ztDEr6rXaJj_n4IOfEwJL0BOqCStHmKHdq3vKCsw9ZLOVzsiA/s320/PCM.jpg" width="320" /></span></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><span style="font-size: large;"><br /></span><div class="page" title="Page 3"><div class="layoutArea"><div class="column"><span style="font-family: 'AdvOTea1a7398'; font-size: large;">Schematic 3D view of projected </span><br /><span style="font-family: 'AdvOTea1a7398'; font-size: large;">phase-change memory devices with lateral geometry.</span><br /><span style="font-family: 'AdvOTea1a7398'; font-size: large;">Credit: Nature Communications</span></div></div></div></td></tr></tbody></table><div class="Default"><span style="font-size: large;"><br /></span></div><div class="Default"><span style="font-size: large;"><span style="font-family: 'Helvetica Neue';">The next morning Koelmans ran into the office of team leader and IBM Fellow <a href="http://researcher.watson.ibm.com/researcher/view.php?person=zurich-ele">Evangelos Eleftheriou</a>, who was astonished<span style="font-family: 'Helvetica Neue';">, and</span></span><span style="font-family: 'Helvetica Neue';"> <span style="font-family: 'Helvetica Neue';">agr<span style="font-family: 'Helvetica Neue';">eed that they <span style="font-family: 'Helvetica Neue';">needed </span></span></span>publish right away.</span></span><span style="font-family: 'Helvetica Neue';"><o:p></o:p></span></div><div class="Default"><span style="font-size: large;"><br /></span></div><div class="Default"><span style="font-family: 'Helvetica Neue'; font-size: large;">Five months later Koelmans and the team delivered. Today in the peer-reviewed journal of <a href="http://www.nature.com/ncomms/2015/150903/ncomms9181/full/ncomms9181.html">Nature Communications</a> (<a href="http://www.nature.com/ncomms/2015/150903/ncomms9181/full/ncomms9181.html">10.1038/NCOMMS9181</a>) this new, radical memory cell design is being reported on for the first time which the team calls projected phase change memory, which features virtually no drift and very little noise. The paper introduces the concept, along with the design, fabrication, and simulation of such devices with the results.</span></div><div class="Default"><span style="font-size: large;"><br /></span></div>                                                                                      <span style="font-family: 'Helvetica Neue'; font-size: large;">IBM scientists believe that projected phase change memory devices could also play a key role in future non-Von Neumann computing paradigms such as brain-inspired, neuromorphic computing.</span>   <br /><a href="http://www.pinterest.com/pin/create/extension/?url=https%3A%2F%2Fwww.blogger.com%2Fblogger.g%3FblogID%3D3821464279005499761%23editor%2Ftarget%3Dpost%3BpostID%3D61242624046173874%3BonPublishedMenu%3Dallposts%3BonClosedMenu%3Dallposts%3BpostNum%3D0%3Bsrc%3Dlink&media=https%3A%2F%2Ffarm6.staticflickr.com%2F5722%2F21114532851_8505903b81_n.jpg&xm=h&xv=sa1.37.01&xuid=tYDKQnV6ndWa&description=" style="background-color: transparent; background-image: url(data:image/png; border: none; cursor: pointer; display: none; height: 20px; left: 353px; opacity: 0.85; position: absolute; top: 24px; width: 40px; z-index: 8675309;"></a><a href="http://www.pinterest.com/pin/create/extension/?url=https%3A%2F%2Fwww.blogger.com%2Fblogger.g%3FblogID%3D3821464279005499761%23editor%2Ftarget%3Dpost%3BpostID%3D61242624046173874%3BonPublishedMenu%3Dallposts%3BonClosedMenu%3Dallposts%3BpostNum%3D0%3Bsrc%3Dlink&media=https%3A%2F%2Ffarm6.staticflickr.com%2F5722%2F21114532851_8505903b81_n.jpg&xm=h&xv=sa1.37.01&xuid=tYDKQnV6ndWa&description=" style="background-color: transparent; background-image: url(data:image/png; border: none; cursor: pointer; display: none; height: 20px; left: 353px; opacity: 1; position: absolute; top: 24px; width: 40px; z-index: 8675309;"></a>

memory nature communications PCM phase change memory zurich Eureka Moments Lead to Radical New Memory Design

Koelmans and Sebastian in the lab where the new memory design was developed IBM researcher Wabe Koelmans had the first significant eureka ...

Growing single-crystalline materials on reusable graphene

5:05 AM N1000 0

<br /><div class="MsoNormal"><i style="mso-bidi-font-style: normal;">Editor’s note: This article is by IBM Research Staff Member and Master Inventor Dr. Jeehwan Kim</i></div><div class="MsoNormal"><br /></div><div class="MsoNormal"><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhiy5Glv0_EzuLaWIplpqDe80w-u75H_nO8B08UjUAy9yT2IO2kQf8Yivbxn3_c3n-7JpCgiYeH58lfz0IvGDvaFP5fHwHEQSg2hahlgbV4St1ymi5Yajhs_qCwMMimfebxDY6-a5RzSj4/s1600/JeehwanKim.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhiy5Glv0_EzuLaWIplpqDe80w-u75H_nO8B08UjUAy9yT2IO2kQf8Yivbxn3_c3n-7JpCgiYeH58lfz0IvGDvaFP5fHwHEQSg2hahlgbV4St1ymi5Yajhs_qCwMMimfebxDY6-a5RzSj4/s1600/JeehwanKim.jpg" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Dr. Jeehwan Kim</td></tr></tbody></table>Since the first demonstrations of removing <a href="http://www.ibm.com/smarterplanet/us/en/innovation_explanations/article/shu-jen_han.html">graphene </a>from graphite a decade ago, the size of a single-oriented piece has been limited to less than a millimeter – far too small for real-world application. Our team<a href="http://ibmresearchnews.blogspot.com/2013/11/exfoliating-wafer-scale-graphene-down.html#fbid=ObF_0p8C7xV"> worked to break through the original millimeter barrier</a>, and together we found success in producing <a href="http://www.sciencemag.org/content/342/6160/833.abstract">wafer-scale, single-crystalline sheets of graphene</a> 100 millimeters (four inches) in diameter. Having achieved scalability, we<span style="mso-fareast-font-family: Batang; mso-fareast-language: KO;"> reported the possibility of replacing a thick, “single-crystalline” wafer with a single-atom-thick graphene layer for growing single-crystalline materials in the paper, “<a href="http://www.nature.com/ncomms/2014/140911/ncomms5836/full/ncomms5836.html" target="_blank">Principle of direct van der Waals epitaxy of single-crystalline films onepitaxial graphene</a>” – published today with my chief collaborator Dr. Can Bayram in <i style="mso-bidi-font-style: normal;">Nature Communications</i>.</span></div><div class="MsoNormal"><br /></div><div class="MsoNormal">Graphene holds incredible promise as a linchpin material for breakthroughs in numerous technologies, and my team at IBM’s Thomas J. Watson Research Center is working to make its potential a reality. Due to its incredible strength and supreme electrical, optical and mechanical properties, graphene – pure carbon functional at the thickness of one atom – has been touted as the next big thing in everything from high-frequency transistors and photo-detectors, to flexible electronics and biosensors. <a href="https://www-03.ibm.com/press/us/en/pressrelease/44357.wss">IBM is investing $3B over the next five years</a> towards initiatives such as this, which are building a bridge to a “post-silicon” era. </div><div class="MsoNormal"><br /></div><div class="MsoNormal">Part of what makes the material so promising is its strength relative to thickness. At only .3 to .4 nanometers thick (that’s 60,000 times thinner than a sheet of plastic wrap, or 1,000,000 times thinner than a strand of human hair), graphene is an astonishing 200 times stronger than steel. It is also the world’s most conductive material yet discovered, extraordinarily flexible and – as a single layer of carbon atoms – the first two-dimensional material.</div><div class="MsoNormal"><br /></div><div class="MsoNormal"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsft78uMX0tr5PO-7FFiyYErqB8y0OiqAaPHi2KIo4yfIbHxE2GViPjFArLLP7rq3WUq46j7Tfbis8LOl5oSOK5Z18L-6pEqV3jDPlE3rly7I9UHGugBRGnS1YWift-n-AxwDTR6EaYJs/s1600/graphene_reuse.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="153" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsft78uMX0tr5PO-7FFiyYErqB8y0OiqAaPHi2KIo4yfIbHxE2GViPjFArLLP7rq3WUq46j7Tfbis8LOl5oSOK5Z18L-6pEqV3jDPlE3rly7I9UHGugBRGnS1YWift-n-AxwDTR6EaYJs/s1600/graphene_reuse.jpg" width="320" /></a></div>Our groundbreaking approach, known as “graphene-based growth/transfer,” allows single-crystalline semiconductor film growth on graphene – rather than on expensive, single-crystalline wafers. The graphene serves as a “seed” for single-crystalline film growth, and because this film can be separated precisely from the graphene surface, the graphene can be reused for further growth. In principle, graphene has therefore been demonstrated as an infinitive source for growing these semiconductor materials, making the work an enormously cost-effective and reliable production method for single-crystalline films. </div><div class="MsoNormal"><br /></div><div class="MsoNormal"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEic_VO5hM7Et9uQmkYvWqAK4cTbkcp3-YpJ_CUGf_vpU3ihx6tYOgSMF7eITzaE-GD1jALwLbvwEodtoleRdC4l81SwWAuhf0eD_Z7n1dvblaHY5lRFQusQ4x7GULGpOkZPVa_Q54_RWxI/s1600/singlecrystal_GaN.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="198" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEic_VO5hM7Et9uQmkYvWqAK4cTbkcp3-YpJ_CUGf_vpU3ihx6tYOgSMF7eITzaE-GD1jALwLbvwEodtoleRdC4l81SwWAuhf0eD_Z7n1dvblaHY5lRFQusQ4x7GULGpOkZPVa_Q54_RWxI/s1600/singlecrystal_GaN.jpg" width="200" /></a>Graphene’s periodic hexagonal crystal structure then allowed us to experiment with growing other semiconductor materials that demonstrate similar structural properties. Previously, production of single-crystalline semiconductor films required the use of ~1 millimeter-thick, single-crystalline wafer templates that were not reusable and were very expensive. For example, growth of a 4-inch, wafer-scale GaN (gallium nitride, a direct bandgap semiconductor) film would require a 4-inch SiC wafer – at the cost of some $3000. Now, graphene can be produced in a lab to replace the expensive SiC wafer. </div><div class="MsoNormal"><br /></div><div class="MsoNormal">Furthermore, the new growth technique is useful in that semiconductor devices can be deposited on graphene and released or transferred to a flexible substrate.</div><div class="MsoNormal"><br /></div><div class="MsoNormal">While we have demonstrated an important, present-day use for this material, the future of graphene as a standalone material is still bright. Uses for graphene are being developed for a number of electronics, and over the next five years, the material could be used as transparent electrodes for touch screen devices, rollable e-paper and foldable LEDs. In the near future, uses are being developed for large-area graphene in high-frequency transistors, logic transistors/thin-film transistors and beyond. Its high electronic mobility – the ability of charged particles to move through a medium in response to an electronic field – makes graphene a promising material. </div><div class="MsoNormal"><br /></div><span style="font-family: "Calibri","sans-serif"; font-size: 11.0pt; line-height: 115%; mso-ansi-language: EN-US; mso-ascii-theme-font: minor-latin; mso-bidi-font-family: "Times New Roman"; mso-bidi-language: AR-SA; mso-bidi-theme-font: minor-bidi; mso-fareast-font-family: Calibri; mso-fareast-language: EN-US; mso-fareast-theme-font: minor-latin; mso-hansi-theme-font: minor-latin;">Read </span><i style="mso-bidi-font-style: normal;"><span style="font-family: "Calibri","sans-serif"; font-size: 11.0pt; line-height: 115%; mso-ansi-language: EN-US; mso-ascii-theme-font: minor-latin; mso-bidi-font-family: "Times New Roman"; mso-bidi-language: AR-SA; mso-bidi-theme-font: minor-bidi; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: KO; mso-hansi-theme-font: minor-latin;"><a href="http://www.nature.com/ncomms/2014/140911/ncomms5836/full/ncomms5836.html" target="_blank">Principle of direct van der Waals epitaxy of single-crystalline films on epitaxial graphene</a> </span></i><span style="font-family: "Calibri","sans-serif"; font-size: 11.0pt; line-height: 115%; mso-ansi-language: EN-US; mso-ascii-theme-font: minor-latin; mso-bidi-font-family: "Times New Roman"; mso-bidi-language: AR-SA; mso-bidi-theme-font: minor-bidi; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: KO; mso-hansi-theme-font: minor-latin;">by Jeehwan Kim, Can Bayram, Hongsik Park, Cheng-Wei Cheng, Christos Dimitrakopoulos, John A. Ott, Kathleen B. Reuter, Stephen W. Bedell and Devendra K. Sadana </span>

graphene nature communications semiconductor silicon Growing single-crystalline materials on reusable graphene

Editor’s note: This article is by IBM Research Staff Member and Master Inventor Dr. Jeehwan Kim Dr. Jeehwan Kim Since the first demonstratio...