20.4. 2007nokia meeting1 aps march meeting 2007 denver, colorado 5.3.-9.3. 2007 latest in graphene...
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20.4. 2007 NOKIA MEETING 1
APS MARCH MEETING 2007APS MARCH MEETING 2007 Denver, Colorado 5.3.-9.3. 2007Denver, Colorado 5.3.-9.3. 2007
LATEST IN GRAPHENE RESEARCHLATEST IN GRAPHENE RESEARCH Mikko Paalanen
Low Temperature LaboratoryHelsinki University of Technology
20.4. 2007 NOKIA MEETING 2
APS MARCH MEETING 2007APS MARCH MEETING 2007 STATISTICSSTATISTICS
SCIENTIFIC SESSIONS Total 520 Graphene sessions 7 + a
tutorial session Carbon nanotube sessions 14
INVITED TALKS Total 720 Graphene talks 10 (6 E, 4 T) Carbon nanotube talks 11 (8 E, 3 T)
20.4. 2007 NOKIA MEETING 3
STATISTICSSTATISTICS
Contributed talks about graphene Total 66
Theory talks 37
ExperimentalElectron transport 14Mechanical properties 9Microscopy 6
29
More experiments needed, theory is advancing fast
20.4. 2007 NOKIA MEETING 4
COMPETITORS COMPETITORS ON EXPERIMENTAL SIDEON EXPERIMENTAL SIDE
Univ. of Manchester (Andrei Geim et al since 2004) Georgia Tech (Walter DeHeer et al) Colombia University (Philip Kim et al) Rutgers University (Eva Andrei et al) IBM Yorktown (Avouris et al) Cornell University (Paul McEuen et al)
20.4. 2007 NOKIA MEETING 5
THREE INTERESTING THREE INTERESTING RESULTSRESULTS
Colombia University (Philip Kim et al) IBM Yorktown (Avouris et al) Leiden University (Carlo Beenakker et al)
20.4. 2007 NOKIA MEETING 6
ENERGY BAND GAP ENGINEERING OF ENERGY BAND GAP ENGINEERING OF GRAPHENE NANORIBBONSGRAPHENE NANORIBBONS
arXiv:cond-mat/0702511arXiv:cond-mat/0702511Colombia, Philip Kim et alColombia, Philip Kim et al
20.4. 2007 NOKIA MEETING 7
Dead edge of the order of 15 nm!Dead edge of the order of 15 nm!
20.4. 2007 NOKIA MEETING 8
Energy gap scales as 1/(w – wEnergy gap scales as 1/(w – w00) ) No orientation dependenceNo orientation dependence
wwminmin = 15 nm = 15 nmEEgmax gmax = 200 meV= 200 meV
20.4. 2007 NOKIA MEETING 9
IBM, AVOURIS et alIBM, AVOURIS et alarXiv:cond-mat/0701599arXiv:cond-mat/0701599
1/f noise similar to CNT1/f noise similar to CNTDue to resistance fluctuationsDue to resistance fluctuations
wwminmin = 20 nm = 20 nmEEgmax gmax = 30 meV= 30 meV
20.4. 2007 NOKIA MEETING 10
SNS-JUNCTION IN GRAPHENESNS-JUNCTION IN GRAPHENELeiden University, Carlo BeenakkerLeiden University, Carlo Beenakker
arXiv:cond-mat/0609623arXiv:cond-mat/0609623
Supercurrent creates a transverseSupercurrent creates a transversespin and thermal currentsspin and thermal currents
Thermal current depends Thermal current depends on phase differenceon phase difference
20.4. 2007 NOKIA MEETING 11
WHY GRAPHENEWHY GRAPHENEWHY NOT CARBON NANOTUBESWHY NOT CARBON NANOTUBES
High electron mobility even at room temperature Long mean free path, electron backscattering weak Long coherence length (dephasing due to e-e collisions)
Contacts easier to make than for nanotubes Can be fabricated lithographically as large wafers (SiC) Metallic interconnects may not be needed Promise for new type of electronics
Electron wave guide electronics Terahertz detectrors .....
20.4. 2007 NOKIA MEETING 12
INTERESTING QUESTIONSINTERESTING QUESTIONS
How do electronic properties depend on substrate? Free standing sheet versus SiC Multilayered graphene Interphase states and doping
What about narrow wires and quantum dots? Rough edges seem to play a role? How to prepare smooth edges? Tuning of the gap in narrow wires?