Identification of electric dipole moments of excitonic complexes in nitride-based quantum dots

Manifestation of unconventional biexciton states in quantum dots

“…We can observe a striking agreement between experiment and theory that already supports the identification of the hybrid-XX. The only parameters that had to be matched to the experiment for the simulation are the linewidth induced by spectral diffusion 44,45 and the particular excitation power and temperature dependencies, varying the intensity balance between X1, X2, XX as shown in Supplementary Figs 2 and 3. Neither material nor geometric QD parameters were varied to approach the measurement causing the apparent slight discrepancies for the luminescence energies.…”

“…Therefore, also the bright X states show a QD anisotropy-dependent smaller fine-structure splitting of E1 meV in the simulations and a slightly larger hybrid XX-binding energy. The visible emission energy variations of the measured emission lines (a) during the polarization angle scan are caused by the spectral diffusion in GaN/AlN QDs 44,45 , which can be suppressed by lowering the temperature, sacrificing the intensity balance of the bright exciton states (see Fig. 5).…”

“…ARTICLE equalize R1 and R2*, proving the existence of a phonon-limited hybrid-XX cascade including a transition from the dark to the bright X states. The apparent temporally broad (E ± 25 ns) bunching phenomenon in both correlation functions arises from spectral diffusion 44,45 and is modelled as described by Sallen et al 55 . Further standard techniques for the identification of QD emission lines are discussed in Supplementary Note 2.…”

Measurement of the Emission Lifetime of a GaN Interface Fluctuation Quantum Dot by Power Dependent Single Photon Dynamics

“…However, III‐Nitrides have limitations because they suffer from a spectral diffusion induced linewidth broadening (which can result in emission linewidths of a few meV) . This spectral diffusion occurs due to an interaction between the internal‐field induced exciton permanent dipole moment and the fluctuating electric field of charges trapped in relatively large densities of surrounding defects . Recently, interface fluctuation GaN QDs have been successfully fabricated, which exhibit narrow emission linewidths and ultra‐clean single photon emission …”

Spectral diffusion in nitride quantum dots: Emission energy dependent linewidths broadening via giant built‐in dipole moments

“…The general phenomenon of spectral diffusion was first described in nuclear magnetic resonance experiments 17, 18 and was then applied to light‐emitting systems such as rare‐earth ions 19, nitrogen vacancies in diamond 20, and semiconductor QDs 21–23. For the case of a semiconductor QD the emitter can be situated in a semiconductor matrix material containing defects that stochastically trap and release charges and hence generate a fluctuating Coulomb field 24. As a consequence an exciton inherent to the QD senses the charged defects in the matrix material mediated by a basic electrostatic interaction resulting in a continuous change of the associated emission energy.…”