Enhanced phonon-assisted absorption in single InAs/GaAs quantum dots

Resonant spectroscopy of II-VI self-assembled quantum dots: Excited states and exciton–longitudinal optical phonon coupling

“…1a. Similar LO phonon-related absorption lines have been recently found for single InAs QDs [24] and single CdSe QDs [25]. Typically we observe up to three such resonances and the linewidth of all replicas is approximately the same.…”

“…We tentatively assign them to the direct excited state (ES) -ground state (GS) excitations (see inset to Fig.1b). It seems that on average the ES energy for CdTe QDs is significantly larger than, for instance, that observed for InAs [24] or CdSe QDs [25]. Since the ES-GS splitting is associated with the strength of spatial confinement, we may conclude that excitons in these CdTe QDs are very strongly confined.…”

Enhanced Exciton–Phonon Coupling in Colloidal Type-II CdTe-CdSe Heteronanocrystals

“…32 Further, it has been argued that the coupling is highly sensitive to the exact form of the electron and hole wave functions. 52 Extrinsic effects such as the presence of charged point defects and surface trapping have also been invoked. 12,13,31,42,43,52 In the specific case of CdSe QDs, the experimental values reported in the literature for the Huang−Rhys parameter S vary by 2 orders of magnitude (viz., from 0.03 to 3).…”

“…52 Extrinsic effects such as the presence of charged point defects and surface trapping have also been invoked. 12,13,31,42,43,52 In the specific case of CdSe QDs, the experimental values reported in the literature for the Huang−Rhys parameter S vary by 2 orders of magnitude (viz., from 0.03 to 3). 24,25,32,43−50 This large disparity can be rationalized by considering that the S values have been deduced from different photophysical properties (viz., homogeneous linewidths, exciton dephasing rates, intensity ratios, etc.…”

Single photon emission with high degree of circular polarization from a single quantum dot under zero magnetic field

“…Figure 3(a) illustrates the results of the photoluminescence-excitation (PLE) measurements detected at both the X + and X − lines. There is striking difference between two charged exciton species, i.e., the X − line was almost quenched below about 85 meV from the detection energy, while the X + survived at lower energy and much richer structures tentatively attributed to phonon resonances and excitation states [15][16][17][18] were observed. For delocalized state excitation, since the absorption coefficient is identical for both the neutral and charged trions, carrier capture process will determine the exciton charging states [11,12].…”