Nanoelectronics could get a boost from carbon research

 

A carbyne strand forms in laser-melted graphite. Carbyne is found in astrophysical bodies and has the potential to be used in nanoelectronic devices and superhard materials. Credit: Image by Liam Krauss/LLNL The smallest of electronics could one day have the ability to turn on and off on an atomic scale. Lawrence Livermore scientists have investigated a way to create linear chains of carbon atoms from laser-melted graphite. The material, called carbyne, could have a number of novel properties, including the ability to adjust the amount of electrical current traveling through a circuit, depending on the user's needs. Carbyne is the subject of intense research because of its presence in astrophysical bodies, as well as its potential use in nanoelectronic devices and superhard materials. Its linear shape gives it unique electrical properties that are sensitive to stretching and bending, and it is 40 times stiffer than diamond. It also was found in the Murchison and Allende meteorites and could be an ingredient of interstellar dust. Using computer simulations, LLNL scientist Nir Goldman and colleague Christopher Cannella (an undergraduate summer researcher from Caltech) initially intended to study the properties of liquid carbon as it evaporates, after being formed by shining a laser beam on the surface of graphite. The laser can heat the graphite surface to a few thousands of degrees, which then forms a fairly volatile droplet. To their surprise, as the liquid droplet evaporated and cooled in their simulations, it formed bundles of linear chains of carbon atoms. "There's been a lot of speculation about how to make carbyne and how stable it is," Goldman said. "We showed that laser melting of graphite is one viable avenue for its synthesis. If you regulate carbyne synthesis in a controlled way, it could have applications as a new material for a number of different research areas, including as a tunable semiconductor or even for hydrogen storage. "Our method shows that carbyne can be formed easily in the laboratory or otherwise. The process also could occur in astrophysical bodies or in the interstellar medium, where carbon containing material can be exposed to relatively high temperatures and carbon can liquefy." Goldman's study and computational models allow for direct comparison with experiments and can help determine parameters for synthesis of carbon-based materials with potentially exotic properties. "Our simulations indicate a possible mechanism for carbyne fiber synthesis that confirms previous experimental observation of its formation," Goldman said. "These results help determine one set of thermodynamic conditions for its synthesis and could account for its detection in meteorites resulting from high-pressure conditions due to impact."   Story Source: The above post is reprinted from materials provided by DOE/Lawrence Livermore National Laboratory. Note: Materials may be edited for content and length. http://www.sciencedaily.com/releases/2015/09/150917135304.htm

Nanoelectronic Device Metrology

. Christina Hacker characterizes the individual monolayers prior to flip-chip lamination using a Fourier transform infrared spectrometer. Summary: The Nanoelectronic Device Metrology (NEDM) project is developing the measurement science infrastructure that will enable innovation and advanced manufacturing of emerging nanoelectronic information processing technologies – including those based upon new computational state variables – to more rapidly enter into the marketplace. Description: The Nanoelectronic Device Metrology project conducts research to develop and advance the measurements needed to understand and evaluate properties of promising nanoelectronic technologies. This involves pioneering research in the area of molecular interfaces, condensed matter physics, alternate means of computing, and confined structures (graphene, 2D materials, nanowires, etc.). Particular emphasis is placed on novel measurements of chemical, physical, and electrical properties to fully interrogate nanoelectronic systems and provide the measurement foundation for advanced manufacturing of innovative future nanoelectronic devices. Core competencies include developing surface, electrical, and magnetic characterization approaches to accelerate the development and characterization of advanced nanoelectronic devices. The NEDM project focuses on understanding the factors that govern charge transport in nanoelectronic devices. To do this, team members focus on novel measurement approaches such as investigating electronic devices at low-temperature or in the presence of a magnetic field. This work is an integral component to the condensed matter physics foundation needed for novel electronic materials (e.g., graphene) and alternate means of computing (e.g., spin) to become a manufactural reality. The NEDM project has extensive expertise in molecular electronics foundations including the formation and characterization of molecular layers and fabrication and qualification of electrode-molecule-electrode junctions which feed into to a fundamental understanding of charge transport at molecular interfaces. This work has led to many technological advances on the nanoscale and has recently been applied to fabricate and understand the physics governing novel organic spintronic devices. The NEDM aims to develop the required measurement infrastructure and scientific knowledge-base to address technology barriers and enable the successful development and subsequent manufacture of next-generation "Beyond CMOS technologies." To do this, the NEDM project supplements our core expertise with collaborations within the nanoelectronics group, across NIST, and with external technical leaders to conduct timely, impactful research. Major Accomplishments: 2015 A sophisticated suite of measurements was combined to understand the surface morphology effects where the metal contacts 2D materials (MoS2) to better understand the factors that limit device performance with novel materials. A series of spectroscopic and electronic experiments to take advantage of the properties of organic monolayers on ferromagnetic materials to control the interface structure and modify spin-injection. 2014 Summarized our expertise in fabricating and characterizing molecular junctions in an invited book chapter that details various approaches to make reliable contact to molecular layers and methods to successfully characterize fully formed junctions. Interface Engineering To Control Magnetic Field Effects of Organic-Based Devices by Using a Molecular Self-Assembled Monolayer. (ACS Nano 2014 10.1021/nn502199z) 2013 Applied extensive nanowire expertise to create novel topological insulator Bi2Se3 nanowire high performance field-effect transistors that open up a suite of potential applications in nanoelectronics and spintronics. (Nature Nanotechnology, Scientific Reports 3, 1757, April 2013.) "Clean and Crackless" transfer method of graphene adopted as preferred fabrication approach for graphene nanoelectronics. (2011 ACS Nano "Highly Cited Paper" as designated by Web of Science) http://www.nist.gov/pml/div683/grp04/nedm.cfm