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Connecting Dopant Bond Type with Electronic Structure in N-Doped Graphene
Schiros, Theanne,Nordlund, Dennis,Pá,lovax301,, Lucia,Prezzi, Deborah,Zhao, Liuyan,Kim, Keun Soo,Wurstbauer, Ulrich,Gutiex301,rrez, Christopher,Delongchamp, Dean,Jaye, Cherno,Fischer, Daniel American Chemical Society 2012 Nano letters Vol.12 No.8
<P>Robust methods to tune the unique electronic properties of graphene by chemical modification are in great demand due to the potential of the two dimensional material to impact a range of device applications. Here we show that carbon and nitrogen core-level resonant X-ray spectroscopy is a sensitive probe of chemical bonding and electronic structure of chemical dopants introduced in single-sheet graphene films. In conjunction with density functional theory based calculations, we are able to obtain a detailed picture of bond types and electronic structure in graphene doped with nitrogen at the sub-percent level. We show that different N-bond types, including graphitic, pyridinic, and nitrilic, can exist in a single, dilutely N-doped graphene sheet. We show that these various bond types have profoundly different effects on the carrier concentration, indicating that control over the dopant bond type is a crucial requirement in advancing graphene electronics.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2012/nalefd.2012.12.issue-8/nl301409h/production/images/medium/nl-2012-01409h_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl301409h'>ACS Electronic Supporting Info</A></P>
Local Atomic and Electronic Structure of Boron Chemical Doping in Monolayer Graphene
Zhao, Liuyan,Levendorf, Mark,Goncher, Scott,Schiros, Theanne,Pá,lovax301,, Lucia,Zabet-Khosousi, Amir,Rim, Kwang Taeg,Gutiex301,rrez, Christopher,Nordlund, Dennis,Jaye, Cherno,Hybertsen, Mar American Chemical Society 2013 Nano letters Vol.13 No.10
<P>We use scanning tunneling microscopy and X-ray spectroscopy to characterize the atomic and electronic structure of boron-doped and nitrogen-doped graphene created by chemical vapor deposition on copper substrates. Microscopic measurements show that boron, like nitrogen, incorporates into the carbon lattice primarily in the graphitic form and contributes ∼0.5 carriers into the graphene sheet per dopant. Density functional theory calculations indicate that boron dopants interact strongly with the underlying copper substrate while nitrogen dopants do not. The local bonding differences between graphitic boron and nitrogen dopants lead to large scale differences in dopant distribution. The distribution of dopants is observed to be completely random in the case of boron, while nitrogen displays strong sublattice clustering. Structurally, nitrogen-doped graphene is relatively defect-free while boron-doped graphene films show a large number of Stone-Wales defects. These defects create local electronic resonances and cause electronic scattering, but do not electronically dope the graphene film.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2013/nalefd.2013.13.issue-10/nl401781d/production/images/medium/nl-2013-01781d_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl401781d'>ACS Electronic Supporting Info</A></P>