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Thin graphite overlayers: Graphene and alkali metal intercalation

Jonathan Algdal (Institutionen för teknisk fysik, Fasta tillståndets fysik) ; T. Balasubramanian ; Marcus Breitholtz (Institutionen för teknisk fysik, Fasta tillståndets fysik) ; Theresa Kihlgren ; Lars Wallden (Institutionen för teknisk fysik)
Surface Science (0039-6028). Vol. 601 (2007), 4, p. 1167-1175.
[Artikel, refereegranskad vetenskaplig]

Using LEED and angle resolved photoemission for characterisation we have prepared graphite overlayers with down to monolayer thickness by heating SiC crystals and monitored alkali metal intercalation for the multilayer films. The valence band structure of the monolayer is similar to that calculated for graphene though downshifted by around 0.8 eV and with a small gap at the zone corner. The shift suggests that the transport properties, which are of much present interest, are similar to that of a biased graphene sample. Upon alkali metal deposition the 3D character of the pi states is lost and the resulting band structure becomes graphene like. A comparison with data obtained for ex situ prepared intercalation compounds indicates that the graphite film has converted to the stage I compounds C8K or CgRb. Advantages with the present preparation method is that the graphite film can be recovered by desorbing small amounts of alkali metal and that the progress of compound formation can be monitored. The energy shifts measured after different deposits indicate that saturation is reached in three steps. Our interpretation is that in the first the alkali atoms are dispersed while the final steps are characterized by the formation of first one and then a second (2 x 2) ordered alkali metal layer adjacent to the uppermost carbon layer. (c) Elsevier B.V. All rights reserved.

Nyckelord: angle resolved photoemission, graphite, alkali metal, intercalation, graphene, silicon carbide, ANGLE-RESOLVED PHOTOEMISSION, ULTRAVIOLET PHOTOELECTRON-SPECTROSCOPY, SCANNING-TUNNELING-MICROSCOPY, ELECTRONIC BAND-STRUCTURE, SINGLE-CRYSTAL GRAPHITE, SYNCHROTRON-RADIATION, SUBMONOLAYER POTASSIUM, CHARGE-TRANSFER, SURFACE, C8K



Denna post skapades 2008-11-07. Senast ändrad 2008-11-12.
CPL Pubid: 77285

 

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Institutioner (Chalmers)

Institutionen för teknisk fysik, Fasta tillståndets fysik (2005-2015)
Institutionen för teknisk fysik (1900-2015)

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Teknisk fysik

Chalmers infrastruktur