Boron doping effect 1. Effect on structure B a.C: 3 sp 2 (3  ) and 1 2p z (1  ) bonds B: 3 sp2 (3  ) b. Bond length: C-C = 1.42 Å, B-C = 1.55 Å c. Electrical.

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Boron doping effect 1. Effect on structure B a.C: 3 sp 2 (3  ) and 1 2p z (1  ) bonds B: 3 sp2 (3  ) b. Bond length: C-C = 1.42 Å, B-C = 1.55 Å c. Electrical ring current (resonance) disappears when B substitutes C

2. Effect on electronic profile CNT metallic EFEF CB VB Semiconductor EFEF CB VB EgEg

BC 3 tube Free electronic-like (metallic) EFEF CB VB  **

2. Effect on electronic profiles Random doping of B in CNT metallic EFEF CB VB Semiconductor EFEF CB VB E F depression to VB edge more than 2 sub-bands crossing at E F i.e. conductance increases BC 3 state (acceptor) EgEg New E g E g reduction by E F depression

B-doping a.E F depression  E g reduction (semiconductor tube) and number of conduction channel increase (conductance > 4e 2 /h, metallic tube). b. Creation of acceptor state near to VB edge and increase in hole carrier density (1  spins/g for CNTs, 6  spins/g for BCNTs). c. Electron scattering density increase by B-doping centers (i.e. shorter mean free path and relaxation time  compared with CNTs,  = 0.4 ps and 4-10 ps for BCNTs and CNTs) B+B+ e-e- scattering d. The actual conductivity depends on competition between scattering density and increase in hole carrier (in practice, the latter > the former, so conductance  )

e. Electron hopping magnitude in  -band increase B dopant  -band (VB)  -band (CB) e-e- hopping  -band (CB) Overlap of  -electron wave function BC 3 state

f. Less influence on conductivity upon strain application For CNT R Deflection angle

Temporary formation of sp 3 character upon bending Resistance reduction is due to (i) temporary formation of sp 3 at bend region and (ii) increasing hopping magnitude upon bending bending Planar sp 2 Tetrahedral sp 3

e - hopping bending planar  -band  -band

For BCNTs  -band BC 3 -state is less affected by bending, so channel remains opened for conduction.  -band is blocked by bending (note that tube bending induced distortion only occurs in  -wave function and valence band essentially remains intact, if, only if, distortion also takes place in valence band the tube fracture occurs)