Seed-Initiated Anisotropic Growth of Unidirectional Armchair Graphene Nanoribbon Arrays on Germanium.

Title Seed-Initiated Anisotropic Growth of Unidirectional Armchair Graphene Nanoribbon Arrays on Germanium.
Authors A.J. Way; R.M. Jacobberger; M.S. Arnold
Journal Nano Lett
DOI 10.1021/acs.nanolett.7b04240

It was recently discovered that the chemical vapor deposition (CVD) of CH4 on Ge(001) can directly yield long, narrow, semiconducting nanoribbons of graphene with smooth armchair edges. These nanoribbons have exceptional charge transport properties compared with nanoribbons grown by other methods. However, the nanoribbons nucleate at random locations and at random times, problematically giving rise to width and bandgap polydispersity, and the mechanisms that drive the anisotropic crystal growth that produces the nanoribbons are not understood. Here, we study and engineer the seed-initiated growth of graphene nanoribbons on Ge(001). The use of seeds decouples nucleation and growth, controls where growth occurs, and allows graphene to grow with lattice orientations that do not spontaneously form without seeds. We discover that when the armchair direction (i.e., parallel to C-C bonds) of the seeds is aligned with the Ge?110? family of directions, the growth anisotropy is maximized, resulting in the formation of nanoribbons with high-aspect ratios. In contrast, increasing misorientation from Ge?110? yields decreasingly anisotropic crystals. Measured growth rate data are used to generate a construction analogous to a kinetic Wulff plot that quantitatively predicts the shape of graphene crystals on Ge(001). This knowledge is employed to fabricate regularly spaced, unidirectional arrays of nanoribbons and to significantly improve their uniformity. These results show that seed-initiated graphene synthesis on Ge(001) will be a viable route for creating wafer-scale arrays of narrow, semiconducting, armchair nanoribbons with rationally controlled placement and alignment for a wide range of semiconductor electronics technologies, provided that dense arrays of sub-10 nm seeds can be uniformly fabricated in the future.

Citation A.J. Way; R.M. Jacobberger; M.S. Arnold.Seed-Initiated Anisotropic Growth of Unidirectional Armchair Graphene Nanoribbon Arrays on Germanium.. Nano Lett. 2018. doi:10.1021/acs.nanolett.7b04240

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See more Germanium products. Germanium (atomic symbol: Ge, atomic number: 32) is a Block P, Group 14, Period 4 element with an atomic weight of 72.63. Germanium Bohr ModelThe number of electrons in each of germanium's shells is 2, 8, 18, 4 and its electron configuration is [Ar] 3d10 4s2 4p2. The germanium atom has a radius of 122.5 pm and a Van der Waals radius of 211 pm. Germanium was first discovered by Clemens Winkler in 1886. In its elemental form, germanium is a brittle grayish white semi-metallic element. Germanium is too reactive to be found naturally on Earth in its native state. High Purity (99.999%) Germanium (Ge) MetalIt is commercially obtained from zinc ores and certain coals. It is also found in argyrodite and germanite. It is used extensively as a semiconductor in transitors, solar cells, and optical materials. Other applications include acting an alloying agent, as a phosphor in fluorescent lamps, and as a catalyst. The name Germanium originates from the Latin word "Germania" meaning "Germany."


See more Carbon products. Carbon (atomic symbol: C, atomic number: 6) is a Block P, Group 14, Period 2 element. Carbon Bohr ModelThe number of electrons in each of Carbon's shells is 2, 4 and its electron configuration is [He]2s2 2p2. In its elemental form, carbon can take various physical forms (known as allotropes) based on the type of bonds between carbon atoms; the most well known allotropes are diamond, graphite, amorphous carbon, glassy carbon, and nanostructured forms such as carbon nanotubes, fullerenes, and nanofibers . Carbon is at the same time one of the softest (as graphite) and hardest (as diamond) materials found in nature. It is the 15th most abundant element in the Earth's crust, and the fourth most abundant element (by mass) in the universe after hydrogen, helium, and oxygen. Carbon was discovered by the Egyptians and Sumerians circa 3750 BC. It was first recognized as an element by Antoine Lavoisier in 1789.

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