Electrical Switching in Carbon Nanotubes and Conformational Transformation of Chain Molecules. 2006. 8. 30. Jisoon Ihm School of Physics, Seoul National University. Collaborators. Sangbong Lee, Seungchul Kim, Byoung Wook Jeong (Seoul Nat’l Univ.)
Electrical Switching in Carbon Nanotubes and Conformational Transformation of Chain Molecules
2006. 8. 30
School of Physics, Seoul National University
Basics:Substitutional Impurity in Metallic Carbon Nanotubes Transformation of Chain Molecules
Boron or Nitrogen
Electronic Structure of Metallic Armchair Nanotube Transformation of Chain Molecules
Band structure of a (10,10) single-wall nanotube ( LDA, first-principles pseudopotential method )
CBM Transformation of Chain Molecules
Tube axis Transformation of Chain Molecules
Conductance with Boron Impurity Transformation of Chain Molecules
Similarity to acceptor states in semiconductors
H.J. Choi et al, PRL 84, 2917(2000)
Conductance with Nitrogen Impurity Transformation of Chain Molecules
Similarity to donor states in semiconductors
I. Electrical switching in metallic carbon nanotubes Transformation of Chain Molecules
( Y.-W. Son, J. Ihm, etc., Phys. Rev. Lett. 95, 216602(2005) )
1. Motivation Transformation of Chain Molecules
C. Dekker, A. Zettl
1. Motivations – cont’d Transformation of Chain Molecules
Is it possible to control the conductance of metallic single-wall carbon nanotubes?
S.B. Lee, A. Zettl
Interplay between defects and electric fields
2. Calculational Method Transformation of Chain Molecules
: Landauer formalism
SCattering-state appRoach for eLEctron Transport (SCARLET)
H. J. Choi et al, PRB 59, 2267(1999), and in preparation
Nitrogen Boron Transformation of Chain Molecules
The electronic potential of N(B) is lowered. Levels of quasibound states move down.
The electronic potential of N(B) is raised. Levels of quasibound states move up.
3. B(N) doped (10,10) SWNT
4. Switching in B-N codoped (10,10) SWNT Transformation of Chain Molecules
5. Scaling for larger (n,n) SWNT Transformation of Chain Molecules
∆H ∝ Eext · (diameter)2
6. Switching in (10,10) SWNT with Vacancies Transformation of Chain Molecules
6. Switching in (10,10) with Vacancies – cont’d Transformation of Chain Molecules
Quasibound states move up or down depending on the direction of Eext.
II. Conformational Transform of Azobenzene Molecules Transformation of Chain Molecules
( B.-Y. Choi et al., Phys. Rev. Lett. 96, 156106(2006) )
Azobenzene (AB) : C Transformation of Chain Molecules6H5-N=N-C6H5
Transformation between Transformation of Chain MoleculestransAB and cisAB
(Voltage bias using STM)
Geometries of Transformation of Chain MoleculestAB
Geometries of Transformation of Chain MoleculescAB
Optimal geometry of Transformation of Chain MoleculestAB and cAB
STS for Transformation of Chain MoleculestAB and cAB
Disperse Orange 3 (NH Transformation of Chain Molecules2-C6H4-N=N-C6H4-NO2)
Flat geometry of Transformation of Chain MoleculescAB
Appendix Transformation of Chain MoleculesExample of MATERIAL DESIGN : totalreflection by three nitrogen impurities
Importance of geometric symmetry (equilateral triangle)
Doubly degenerate impurity states cause perfect reflection at 0.6 eV.
(Both even and odd states are fully reflected at same energy.)
Difference between E Transformation of Chain Moleculesext and impurity potential U
Eigenstate |ψ> of Htot associated with the eigenstate |> of H0 with the same energy E (with impurity potential U at site a)
Projection on to the impurity | Transformation of Chain Molecules>
Reflection for the specific state |> :
Total transmission :
Resonance condition :
Effect of E Transformation of Chain Moleculesext : Green’s function itself changes.
: G0 projected at site a
With applied electric fields,
Suppose ∆H at site α is ∆E.
In other words, is G0(α;E) shifted by ∆E.
(10,10) SWNT with single attractive impurity of U=-5|t| Transformation of Chain Molecules
(10,10) SWNT with NO E Transformation of Chain Moleculesext while changing the strength of the attractive potential, U.
EFChanging Eext is different from changing U.
(10,10) SWNT with a single attractive impurity of U=-5|t| while changing Eext
SAMSUNG SDI FED Transformation of Chain Molecules– 2005 -
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