Nanotubes are ideal 1-dimensional conductors and they are either metallic or semi -conducting depending on their chirality. I will present transport measurements performed on semiconducting and metallic single-walled nanotubes. At low temperatures our systems form clean and regular quantum dots. We have measured the addition and excitation energies of these quantum dots. We find 4-electron periodicities in metallic nanotubes, where we can completely identify all electron quantum states. In semiconducting nanotubes we have observed even-odd effects when adding electrons to the quantum dot and a near perfect electron-hole symmetry highlighting the symmetric bandstructure of the nanotube. Furthermore, in measurements on suspended nanotubes additional harmonic excitations appear at low energies that we attribute to phonon assisted tunneling in the nanotube quantum dot. The measurements give us detailed information about electron-phonon, electronelectron and exchange interactions.
Nanotubes are ideal 1-dimensional conductors and they are either metallic or semi -conducting depending on their chirality. I will present transport measurements performed on semiconducting and metallic single-walled nanotubes. At low temperatures our systems form clean and regular quantum dots. We have measured the addition and excitation energies of these quantum dots. We find 4-electron periodicities in metallic nanotubes, where we can completely identify all electron quantum states. In semiconducting nanotubes we have observed even-odd effects when adding electrons to the quantum dot and a near perfect electron-hole symmetry highlighting the symmetric bandstructure of the nanotube. Furthermore, in measurements on suspended nanotubes additional harmonic excitations appear at low energies that we attribute to phonon assisted tunneling in the nanotube quantum dot. The measurements give us detailed information about electron-phonon, electronelectron and exchange interactions.
