Effects of electron-phonon interactions on the electron tunneling spectrum of PbS quantum dots

Hongjian Wang (1) , Emmanuel Lhuillier (1, 2) , Q Yu (1) , A Mottaghizadeh (1) , C Ulysse (3) , A Zimmers (1) , A Descamps-Mandine (1) , Benoit Dubertret (1) , Herve Aubin (1, 4)

1 LPEM - Laboratoire de Physique et d'Etude des Matériaux (UMR 8213)
2 INSP-E6 - Physico-chimie et dynamique des surfaces
3 LPN - Laboratoire de photonique et de nanostructures
4 C2N - Centre de Nanosciences et de Nanotechnologies

We present a tunnel spectroscopy study of single PbS quantum dots (QDs) as a function of temperature and gate voltage. Three distinct signatures of strong electron-phonon coupling are observed in the electron tunneling spectrum (ETS) of these QDs. In the shell-filling regime, the 8× degeneracy of the electronic levels is lifted by the Coulomb interactions and allows the observation of phonon subbands that result from the emission of optical phonons. At low bias, a gap is observed in the ETS that cannot be closed with the gate voltage, which is a distinguishing feature of the Franck-Condon blockade. From the data, a Huang-Rhys factor in the range S ∼ 1.7–2.5 is obtained. Finally, in the shell-tunneling regime, the optical phonons appear in the inelastic ETS d 2 I/dV 2 .

Mots clés: quantum dot; PbS; tunnel spectroscopy; quantum dot

Domaines: Matériaux; Matière Condensée [cond-mat]

Hongjian Wang, Emmanuel Lhuillier, Q Yu, A Mottaghizadeh, C Ulysse, et al.. Effects of electron-phonon interactions on the electron tunneling spectrum of PbS quantum dots. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2015, 92, pp.41403 - 41403. ⟨10.1103/PhysRevB.92.041403⟩. ⟨hal-01438653⟩