Abstract
In this work we study theoretically and experimentally the multi-particle structure of the so-called type-II quantum dots with spatially separated electrons and holes. Our calculations based on customarily developed full configuration interaction ap- proach reveal that exciton complexes containing holes interacting with two or more electrons exhibit fairly large antibinding energies. This effect is found to be the hallmark of the type-II confinement. In addition, an approximate self-consistent solution of the multi-exciton problem allows us to explain two pronounced phenomena: the blue-shift of the emission with pumping and the large inhomogeneous spectral broadening, both of those eluding explanation so far. The results are confirmed by detailed intensity and polarization resolved photoluminescence measurements on a number of type-II samples.
Highlights
In this work we study theoretically and experimentally the multi-particle structure of the socalled type-II quantum dots with spatially separated electrons and holes
We have recently demonstrated a method to determine the vertical position of the hole wavefunction in real samples[23], more obstacles associated with type-II quantum dots (QDs) remain
We provide the theoretical description of the excitonic structure of type-II QDs using a Full Configuration Interaction (CI) method developed for this purpose, as well as the experimental observation of the recombination of multi-particle states by intensity and polarization resolved photoluminescence (PL) measurements
Summary
In this work we study theoretically and experimentally the multi-particle structure of the socalled type-II quantum dots with spatially separated electrons and holes. Because of the inhomogeneous broadening of the spectral bands there has been only a small amount of experimental[24] or theoretical[25,26] studies of the excitonic structure of type-II QDs. there is still an ongoing discussion about the physical nature of the emission energy blue-shift with pumping[27,28,29,30].
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