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Effect of electron injection in copper-contacted graphene nanoribbons

Simonov, Konstantin A. LU ; Vinogradov, Nikolay A. LU ; Vinogradov, Alexander S.; Generalov, Alexander V. LU ; Svirskiy, Gleb I.; Cafolla, Attilio A.; Mårtensson, Nils LU and Preobrajenski, Alexei B. LU (2016) In Nano Research 9(9). p.2735-2746
Abstract

For practical electronic device applications of graphene nanoribbons (GNRs), it is essential to have abrupt and well-defined contacts between the ribbon and the adjacent metal lead. By analogy with graphene, these contacts can induce electron or hole doping, which may significantly affect the I/V characteristics of the device. Cu is among the most popular metals of choice for contact materials. In this study, we investigate the effect of in situ intercalation of Cu on the electronic structure of atomically precise, spatially aligned armchair GNRs of width N = 7 (7-AGNRs) fabricated via a bottom-up method on the Au(788) surface. Scanning tunneling microscopy data reveal that the complete intercalation of about one monolayer of Cu under... (More)

For practical electronic device applications of graphene nanoribbons (GNRs), it is essential to have abrupt and well-defined contacts between the ribbon and the adjacent metal lead. By analogy with graphene, these contacts can induce electron or hole doping, which may significantly affect the I/V characteristics of the device. Cu is among the most popular metals of choice for contact materials. In this study, we investigate the effect of in situ intercalation of Cu on the electronic structure of atomically precise, spatially aligned armchair GNRs of width N = 7 (7-AGNRs) fabricated via a bottom-up method on the Au(788) surface. Scanning tunneling microscopy data reveal that the complete intercalation of about one monolayer of Cu under 7-AGNRs can be facilitated by gentle annealing of the sample at 80 °C. Angle-resolved photoemission spectroscopy (ARPES) data clearly reflect the one-dimensional character of the 7-AGNR band dispersion before and after intercalation. Moreover, ARPES and core-level photoemission results show that intercalation of Cu leads to significant electron injection into the nanoribbons, which causes a pronounced downshift of the valence and conduction bands of the GNR with respect to the Fermi energy (ΔE ~ 0.5 eV). As demonstrated by ARPES and X-ray absorption spectroscopy measurements, the effect of Cu intercalation is restricted to n-doping only, without considerable modification of the band structure of the GNRs. Post-annealing of the 7-AGNRs/Cu/Au(788) system at 200 °C activates the diffusion of Cu into Au and the formation of a Cu-rich surface Au layer. Alloying of intercalated Cu leads to the recovery of the initial position of GNR-related bands with respect to the Fermi energy (EF), thus, proving the tunability of the induced n-doping. [Figure not available: see fulltext.]

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
angle-resolved photoemission spectroscopy (ARPES), bottom-up method, charge injection, copper intercalation, graphene nanoribbons, scanning tunneling microscopy
in
Nano Research
volume
9
issue
9
pages
12 pages
publisher
Springer
external identifiers
  • scopus:84978733976
  • wos:000382882200023
ISSN
1998-0124
DOI
10.1007/s12274-016-1162-2
language
English
LU publication?
yes
id
c033b7f4-96f5-4dfa-a069-98709f8fc627
date added to LUP
2016-11-28 15:18:40
date last changed
2017-04-06 08:12:36
@article{c033b7f4-96f5-4dfa-a069-98709f8fc627,
  abstract     = {<p>For practical electronic device applications of graphene nanoribbons (GNRs), it is essential to have abrupt and well-defined contacts between the ribbon and the adjacent metal lead. By analogy with graphene, these contacts can induce electron or hole doping, which may significantly affect the I/V characteristics of the device. Cu is among the most popular metals of choice for contact materials. In this study, we investigate the effect of in situ intercalation of Cu on the electronic structure of atomically precise, spatially aligned armchair GNRs of width N = 7 (7-AGNRs) fabricated via a bottom-up method on the Au(788) surface. Scanning tunneling microscopy data reveal that the complete intercalation of about one monolayer of Cu under 7-AGNRs can be facilitated by gentle annealing of the sample at 80 °C. Angle-resolved photoemission spectroscopy (ARPES) data clearly reflect the one-dimensional character of the 7-AGNR band dispersion before and after intercalation. Moreover, ARPES and core-level photoemission results show that intercalation of Cu leads to significant electron injection into the nanoribbons, which causes a pronounced downshift of the valence and conduction bands of the GNR with respect to the Fermi energy (ΔE ~ 0.5 eV). As demonstrated by ARPES and X-ray absorption spectroscopy measurements, the effect of Cu intercalation is restricted to n-doping only, without considerable modification of the band structure of the GNRs. Post-annealing of the 7-AGNRs/Cu/Au(788) system at 200 °C activates the diffusion of Cu into Au and the formation of a Cu-rich surface Au layer. Alloying of intercalated Cu leads to the recovery of the initial position of GNR-related bands with respect to the Fermi energy (E<sub>F</sub>), thus, proving the tunability of the induced n-doping. [Figure not available: see fulltext.]</p>},
  author       = {Simonov, Konstantin A. and Vinogradov, Nikolay A. and Vinogradov, Alexander S. and Generalov, Alexander V. and Svirskiy, Gleb I. and Cafolla, Attilio A. and Mårtensson, Nils and Preobrajenski, Alexei B.},
  issn         = {1998-0124},
  keyword      = {angle-resolved photoemission spectroscopy (ARPES),bottom-up method,charge injection,copper intercalation,graphene nanoribbons,scanning tunneling microscopy},
  language     = {eng},
  month        = {09},
  number       = {9},
  pages        = {2735--2746},
  publisher    = {Springer},
  series       = {Nano Research},
  title        = {Effect of electron injection in copper-contacted graphene nanoribbons},
  url          = {http://dx.doi.org/10.1007/s12274-016-1162-2},
  volume       = {9},
  year         = {2016},
}