{"id":14888,"date":"2017-03-31T23:01:41","date_gmt":"2017-03-31T23:01:41","guid":{"rendered":"http:\/\/www.kurzweilai.net\/?p=297405"},"modified":"2017-03-31T23:01:41","modified_gmt":"2017-03-31T23:01:41","slug":"this-advance-could-finally-make-graphene-based-semiconductor-chips-feasible","status":"publish","type":"post","link":"https:\/\/hoo.central12.com\/fugic\/2017\/03\/31\/this-advance-could-finally-make-graphene-based-semiconductor-chips-feasible\/","title":{"rendered":"This advance could finally make graphene-based semiconductor chips feasible"},"content":{"rendered":"
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Atomic force microscopy images of as-deposited (left) and laser-annealed (right) reduced graphene oxide (rGO) thin films. The entire “pulsed laser annealing” process is done at room temperature and atmospheric pressure, using high-power laser pulses to convert p-type rGO material into n-type and completed in about one fifth of a microsecond. (credit: Anagh Bhaumik and Jagdish Narayan\/Journal of Applied Physics)<\/p><\/div>\n

Researchers at North Carolina State University<\/a> (NC State) have developed a layered material that can be used to develop transistors based on graphene<\/a> — a long-sought goal in the electronics industry.<\/p>\n

Graphene has attractive properties, such as extremely high conductivity, meaning it conducts the flow of electrical current really well (compared to copper, for example), but it’s not a semiconductor, so it can’t work in a transistor (aside from providing great connections). A form of graphene called “graphene oxide” is<\/em> a semiconductor, but it does not conduct well.<\/p>\n

However, a form of graphene oxide called “reduced graphene oxide” (rGO) does<\/em> conduct well*. Despite that, rGO still can’t function in a transistor. That’s because the design of a transistor is based on creating a junction between two materials: one that is positively charged (p-type) and one that is negatively charged (n-type), and native rGO is only a p-type.<\/p>\n

The NC State researchers’ solution was to use high-powered laser pulses to disrupt chemical groups on an rGO thin film. This disruption moved electrons from one group to another, effectively converting p-type rGO to n-type rGO. They then used the two forms of rGO as two layers (a layer of n-type rGO on the surface and a layer of p-type rGO underneath) — creating a layered thin-film material that could be used to develop rGO-based transistors for use in future semiconductor chips.<\/p>\n

The researchers were also able to integrate the rGO-based transistors onto sapphire and silicon wafers across the entire wafer.<\/p>\n

The paper was published in the\u00a0Journal of Applied Physics<\/em>. The work was done with support from the National Science Foundation.<\/p>\n

* Reduction\u00a0is a\u00a0chemical\u00a0reaction that involves the gaining of electrons. <\/em><\/p>\n

\n

Abstract of\u00a0Conversion of p to n-type reduced graphene oxide by laser annealing at room temperature and pressure<\/em><\/h4>\n

Physical properties of reduced\u00a0graphene\u00a0oxide (rGO) are strongly dependent on the ratio of\u00a0sp<\/em>2\u00a0to\u00a0sp<\/em>3hybridized\u00a0carbon\u00a0atoms and the presence of different functional groups in its structural framework. This research for the very first time illustrates successful wafer scale integration of graphene-related materials by a\u00a0pulsed laser deposition\u00a0technique, and controlled conversion of\u00a0p<\/em>\u00a0to\u00a0n-<\/em>type 2D rGO by\u00a0pulsed laser\u00a0annealing using a nanosecond ArF excimer laser. Reduced\u00a0graphene\u00a0oxide is grown onto c-sapphire by employing\u00a0pulsed laser deposition\u00a0in a laser MBE chamber and is intrinsically\u00a0p<\/em>-type in nature. Subsequent laser annealing converts\u00a0p<\/em>\u00a0into\u00a0n-<\/em>type rGO. The\u00a0XRD,\u00a0SEM, and Raman spectroscopy indicate the presence of large-area rGO onto c-sapphire having Raman-active vibrational modes: D, G, and 2D. High-resolution SEM and AFM reveal the morphology due to interfacial instability and formation of\u00a0n-<\/em>type rGO. Temperature-dependent\u00a0resistance\u00a0data of rGO thin films follow the Efros-Shklovskii variable-range-hopping model in the low-temperature region and Arrhenius conduction in the high-temperature regime. The\u00a0photoluminescence\u00a0spectra also reveal less intense and broader blue fluorescence spectra, indicating the presence of miniature sized\u00a0sp<\/em>2\u00a0domains in the vicinity of \u03c0* electronic states, which favor the VRH transport phenomena. The\u00a0XPS\u00a0results reveal a reduction of the rGO network after laser annealing with the C\/O ratio measuring as high as 23% after laser-assisted reduction. The\u00a0p<\/em>\u00a0to\u00a0n-<\/em>type conversion is due to the reduction of the rGO framework which also decreases the ratio of the intensity of the D peak to that of the G peak as it is evident from the Raman spectra. This wafer scale integration of rGO with c-sapphire and\u00a0p<\/em>\u00a0to\u00a0n-<\/em>type conversion employing a laser annealing technique at room temperature and pressure will be useful for large-area electronic devices and will open a new frontier for further extensive research in graphene-based functionalized 2D materials.<\/p>\n","protected":false},"excerpt":{"rendered":"

Researchers at North Carolina State University (NC State) have developed a layered material that can be used to develop transistors based on graphene — a long-sought goal in the electronics industry. Graphene has attractive properties, such as extremely high conductivity, meaning it conducts the flow of electrical current really well (compared to copper, for example), […]<\/p>\n","protected":false},"author":13,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[48,43],"tags":[],"class_list":["post-14888","post","type-post","status-publish","format-standard","hentry","category-electronics","category-news"],"_links":{"self":[{"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/posts\/14888"}],"collection":[{"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/users\/13"}],"replies":[{"embeddable":true,"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/comments?post=14888"}],"version-history":[{"count":1,"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/posts\/14888\/revisions"}],"predecessor-version":[{"id":14889,"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/posts\/14888\/revisions\/14889"}],"wp:attachment":[{"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/media?parent=14888"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/categories?post=14888"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/tags?post=14888"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}