Stark Spectroscopy and Radiative Lifetimes in Single Self-Assembled CdTe Quantum Dots

Abstract

We present studies on Coulomb interactions in single self-assembled CdTe quantum dots. We use a field effect structure to tune the charge state of the dot and investigate the impact of the charge state on carrier wave functions. The analysis of the quantum confined Stark shifts of four excitonic complexes allows us to conclude that the hole wave function is softer than electron wave function, i. e. it is subject to stronger modifications upon changing of the dot charge state. These conclusions are corroborated by time-resolved photoluminescence studies of recombination lifetimes of different excitonic complexes. We find that the lifetimes are notably shorter than expected for strong confinement and result from a relatively shallow potential in the valence band. This weak confinement facilitates strong hole wave function redistributions. We analyze spectroscopic shifts of the observed excitonic complexes and find the same sequence of transitions for all studied dots. We conclude that the universality of spectroscopic shifts is due to the role of Coulomb correlations stemming from strong configuration mixing in the valence band.

sent to Physical Review B

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Cited by in corpus (5)

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• Optical study of electron-electron exchange interaction in CdTe/ZnTe quantum dots
• Influence of exciton spin relaxation on the photoluminescence spectra of semimagnetic quantum dots
• Tuning the inter-shell splitting in self-assembled CdTe quantum dots
• Optical signatures of spin dependent coupling in semimagnetic quantum dot molecules