Defect-induced photoluminescence blinking of single epitaxial InGaAs quantum dots.

Fengrui Hu,Xiaoyong Wang,Chunfeng Zhang,Zengle Cao,Min Xiao

doi:10.1038/srep08898

Fengrui Hu, Xiaoyong Wang + Show 3 more

Open Access

https://doi.org/10.1038/srep08898

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Abstract

Here we report two types of defect-induced photoluminescence (PL) blinking behaviors observed in single epitaxial InGaAs quantum dots (QDs). In the first type of PL blinking, the “off” period is caused by the trapping of hot electrons from the higher-lying excited state (absorption state) to the defect site so that its PL rise lifetime is shorter than that of the “on” period. For the “off” period in the second type of PL blinking, the electrons relax from the first excited state (emission state) into the defect site, leading to a shortened PL decay lifetime compared to that of the “on” period. This defect-induced exciton quenching in epitaxial QDs, previously demonstrated also in colloidal nanocrystals, confirms that these two important semiconductor nanostructures could share the same PL blinking mechanism.

Highlights

We report two types of defect-induced photoluminescence (PL) blinking behaviors observed in single epitaxial InGaAs quantum dots (QDs)
PL blinking was rarely observed in single epitaxial QDs, but it could be triggered by introducing physical defects on the sample surface, with the PL ‘‘off’’ periods lasting for hundreds of milliseconds and longer[24,25,26,27,28,29]
Since there are three layers of InGaAs QDs separated by 17 nm in this sample structure, we cannot completely rule out the possibility that each blinking dot might be a localized cluster of several QDs, especially when their emission peaks are all within the,940–960 nm wavelength range

Summary

Introduction

We report two types of defect-induced photoluminescence (PL) blinking behaviors observed in single epitaxial InGaAs quantum dots (QDs). Photoluminescence (PL) blinking has long been observed in a variety of single optical emitters[1,2] ranging from nanocrystal (NC), quantum dot (QD), dye, polymer, porous silicon to fluorescent protein, and most recently even to carbon nanotube[3], nitrogen-vacancy center[4] and silicon carbide[5] This intriguing optical phenomenon was first reported in single colloidal CdSe NCs in 19966 and soon explained by a theoretical model[7] proposing that the blinking ‘‘off’’ period should originate from nonradiative Auger recombination of a charged exciton. For the ‘‘off’’ period in the second type of PL blinking, the electrons relax from the QD emission state into the defect site, leading to an equal PL rise lifetime and a shortened PL decay lifetime compared to those of the ‘‘on’’ period

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