{"id":18637,"date":"2025-09-01T17:58:24","date_gmt":"2025-09-01T09:58:24","guid":{"rendered":"https:\/\/cde.nus.edu.sg\/mse\/?post_type=nus-news&p=18637"},"modified":"2025-09-01T17:58:24","modified_gmt":"2025-09-01T09:58:24","slug":"graphene-sets-new-electronic-benchmark-with-dual-breakthroughs","status":"publish","type":"nus-news","link":"https:\/\/cde.nus.edu.sg\/mse\/news\/graphene-sets-new-electronic-benchmark-with-dual-breakthroughs\/","title":{"rendered":"Graphene sets new electronic benchmark with dual breakthroughs"},"content":{"rendered":"

Graphene, a single sheet of carbon atoms arranged in a honeycomb lattice, is known for its exceptional strength, flexibility and conductivity. However, despite holding the world record for room-temperature electron mobility, graphene\u2019s performance at cryogenic temperatures has remained below that of the best gallium arsenide (GaAs)-based semiconductor systems, which have benefited from many decades of refinement.<\/p>\n

\"\"
Assistant Professor Alexey Berdyugin (Materials Science and Engineering) co-led the studies that achieved record graphene mobility.<\/figcaption><\/figure>\n

One key obstacle is electronic disorder. In practical devices, graphene is highly sensitive to stray electric fields from charged defects in surrounding materials. These imperfections create spatial fluctuations in charge density, known as electron-hole puddles, that scatter electrons and limit mobility. This disorder has prevented graphene from realising its full potential as an ultra-clean electronic system.<\/p>\n

Now, in two parallel studies, researchers from the National University of Singapore (NUS) and The University of Manchester (UK) report distinct strategies that finally push graphene past this long-standing benchmark. The results set new records for electron mobility, matching and in some cases surpassing GaAs in both transport and quantum mobility, and enabling the observation of quantum effects in unprecedented conditions.<\/p>\n

\u201cMobility is a measure of how easily electrons can move through a material when an electric field is applied. High mobility means electrons can travel faster and more freely, which is crucial for building faster and more energy-efficient electronic devices\u201d, said Assistant Professor Alexey Berdyugin from the Department of Materials Science and Engineering, College of Design and Engineering (CDE), NUS. \u201cMaterials with high mobility are especially important for advanced computing, sensing and quantum technologies.\u201d Asst Prof Berdyugin is also a scientist in the Department of Physics at the NUS Faculty of Science.<\/p>\n

\u201cThis opens up opportunities not just for fundamental research, but also for high-performance applications where ultra-clean materials are critical,\u201d he added.<\/p>\n

Twisted graphene and tunable Coulomb screening<\/strong><\/p>\n

In the first study, published in Nature Communications<\/em><\/a> on 11 August 2025 and led by Asst Prof Berdyugin together with collaborators from the United Kingdom, Spain and Japan, the researchers developed a method to shield graphene from environmental disorder by using additional graphene layers as ultra-thin electrostatic screens. They achieved this by stacking two graphene layers with a large relative twist angle (between 10\u00b0 and 30\u00b0), thereby ensuring the layers were electronically decoupled while separated by less than a nanometre.<\/p>\n

One layer could then be deliberately doped to act as a metallic screen, suppressing the fluctuating electric fields from charged impurities that otherwise disrupt electron motion.<\/p>\n

As a result, charge inhomogeneity was reduced to just a few electrons per square micrometre \u2014 an order of magnitude better than state-of-the-art devices. The high quality of the graphene layer enabled the onset of Landau quantisation, which is a hallmark of quantum behaviour in two-dimensional materials, to be observed at magnetic fields of just 5\u20136 milli-Tesla. In most graphene devices, several hundred times stronger fields are required.<\/p>\n

Because the technique minimises scattering from long-range electric field fluctuations, the transport mobility exceeded 20 million cm\u00b2\/Vs, and quantum mobility surpassed that of the best GaAs two-dimensional electron gases.<\/p>\n

\u201cGraphene has finally caught up and even exceeded traditional semiconductors in some critical aspects,\u201d added Mr Ian Babich, a PhD student in CDE and the Institute for Functional Intelligent Materials at NUS and first author of the study. \u201cIt\u2019s a historical moment for graphene devices, and it enables further exploration of delicate quantum phenomena that were previously out of reach.\u201d<\/p>\n

\"\"
Ian Babich, PhD student at NUS and first author, conducting low-temperature measurements of graphene devices.<\/figcaption><\/figure>\n

Proximity metallic screening for record mobilities<\/strong><\/p>\n

The second study, published in Nature<\/a><\/em> on 20 August 2025 and led by Nobel Laureate Sir Andre Geim and Dr Daniil Domaretskiy at the University of Manchester, with Asst Prof Berdyugin as co-corresponding author, took a different approach. Instead of using another graphene layer, the team placed graphene less than one nanometre away from a metallic graphite gate, separated by an ultrathin dielectric made of just three to four atomic layers of hexagonal boron nitride.<\/p>\n

This ultra-close proximity created exceptionally strong Coulomb screening, dramatically reducing disorder and bringing charge inhomogeneity down to around 3×10\u2077 cm\u207b\u00b2, equivalent to roughly one extra charge carrier per 100 million carbon atoms at the charge neutrality point.<\/p>\n

With this level of purity, the devices reached Hall mobilities exceeding 60 million cm\u00b2\/Vs, surpassing the most advanced GaAs-based systems. Quantum Hall plateaus, which normally require magnetic fields of several Tesla, appeared below 5 milli-Tesla. Shubnikov\u2013de Haas oscillations, another quantum signature, were visible at just 1 milli-Tesla, comparable in strength to the pristine magnetic field of the Earth.<\/p>\n

Complementary routes to ultra-clean graphene <\/strong><\/p>\n

The two studies provide complementary solutions to the same longstanding problem: how to protect graphene from the charged defects which are always present in its surrounding materials, which limit its electronic performance.<\/p>\n

\u201cOf course, each approach has its strengths,\u201d said Asst Prof Berdyugin. \u201cLarge twist angle graphene devices provide highly tuneable and controllable screening. On the other hand, proximity screening with graphite separated by a thin dielectric spacer allows us to probe the properties of a pristine graphene layer directly. This way, there is no additional signal from the screening layer, and one can observe absolutely beautiful Quantum Hall plateaus already at a few milli Tesla. Together, those methods expand our experimental toolkit in a way that will benefit the field of two-dimensional materials.\u201d<\/p>\n

The researchers\u2019 breakthroughs could accelerate progress in areas ranging from quantum metrology, where the quantum Hall effect underpins international resistance standards, to ultra-sensitive sensing technologies that depend on pristine electronic behaviour. The exceptional mobilities achieved could also advance next-generation high-speed electronics, where low disorder is critical for performance and energy efficiency. In addition, the methods provide cleaner experimental platforms for exploring correlated electron states relevant to emerging quantum information technologies.<\/p>\n

Looking ahead, the teams aim to adapt these methods to more complex graphene-based heterostructures, including moir\u00e9 quantum materials that host intriguing many-body effects.<\/p>\n

\u201cThese results change what we thought was possible for graphene,\u201d said Mr Babich. \u201cThe performance we can now achieve means there is a whole new space of physics to explore.”<\/p>\n

 <\/p>\n

Article from College of Design and Engineering, NUS<\/em><\/span><\/p>\n","protected":false},"excerpt":{"rendered":"

Graphene, a single sheet of carbon atoms arranged in a honeycomb lattice, is known for its exceptional strength, flexibility and conductivity. However, despite holding the world record for room-temperature electron mobility, graphene\u2019s performance at cryogenic temperatures has remained below that of the best gallium arsenide (GaAs)-based semiconductor systems, which have benefited from many decades of<\/p>\n","protected":false},"author":79,"featured_media":18638,"parent":0,"menu_order":0,"template":"","meta":{"_acf_changed":false,"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"default","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"set","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""}},"footnotes":""},"news_category":[36],"class_list":["post-18637","nus-news","type-nus-news","status-publish","has-post-thumbnail","hentry","news_category-news"],"acf":[],"_links":{"self":[{"href":"https:\/\/cde.nus.edu.sg\/mse\/wp-json\/wp\/v2\/news\/18637","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/cde.nus.edu.sg\/mse\/wp-json\/wp\/v2\/news"}],"about":[{"href":"https:\/\/cde.nus.edu.sg\/mse\/wp-json\/wp\/v2\/types\/nus-news"}],"author":[{"embeddable":true,"href":"https:\/\/cde.nus.edu.sg\/mse\/wp-json\/wp\/v2\/users\/79"}],"version-history":[{"count":1,"href":"https:\/\/cde.nus.edu.sg\/mse\/wp-json\/wp\/v2\/news\/18637\/revisions"}],"predecessor-version":[{"id":18640,"href":"https:\/\/cde.nus.edu.sg\/mse\/wp-json\/wp\/v2\/news\/18637\/revisions\/18640"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/cde.nus.edu.sg\/mse\/wp-json\/wp\/v2\/media\/18638"}],"wp:attachment":[{"href":"https:\/\/cde.nus.edu.sg\/mse\/wp-json\/wp\/v2\/media?parent=18637"}],"wp:term":[{"taxonomy":"news_category","embeddable":true,"href":"https:\/\/cde.nus.edu.sg\/mse\/wp-json\/wp\/v2\/news_category?post=18637"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}