Differential absorption spectroscopy on coupled InGaAs quantum dots

Chuang, Kui-Hao; Chen, C.Y.; Tzeng, T.E.; Feng, David Jui-Yang; Lay, T. S.

doi:10.1016/j.jcrysgro.2008.11.074

Cited by 7 publications

(3 citation statements)

References 7 publications

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“…9 and 25͒, and multilayered QD ensembles with varying interdot barriers 26 and allowed ultrahigh sensitivity. Ser et al applied differential transmission method to the ensemble of VAQDs and observed a single well-resolved optical transition, which exerted an enhanced Stark shift.…”

Section: Samples and Experimentsmentioning

confidence: 99%

Tunnel coupling in an ensemble of vertically aligned quantum dots at room temperature

et al. 2009

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We report unambiguous observation of the formation of mixed electronic states in an ensemble of selfassembled vertically aligned quantum dots at room temperature. Three closely spaced layers containing stacked In͑Ga͒As/GaAs quantum dots are placed in the active region of a two-section semiconductor device, and investigations of the quantum-dot optical properties at different applied electric fields are carried out by means of differential-absorption spectroscopy. A simple semianalytical model, which describes absorption of two layers of coupled quantum dots with an account of the size dispersion, is developed. A comparison between our experimental and theoretical results allows clear attribution of the observed low-photon-energy field-dependent spectral features to the four mixed optical transitions due to the two upper quantum-dot layers. Interpretation of the experimental results reveals an anticrossing of spatially direct and indirect transitions characterized by the energy splitting of approximately 30 meV.

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Section: Samples and Experimentsmentioning

confidence: 99%

Tunnel coupling in an ensemble of vertically aligned quantum dots at room temperature

et al. 2009

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“…According to our previous work [4], InGaAs/GaAs QDs grown by molecular beam epitaxy (MBE) with different spacer thickness shows stronger coupling effect from optical properties and more vertical alignment from transmission electron microscopy (TEM) image as more thinner spacer is achievable until 5 nm.…”

mentioning

confidence: 93%

Photovoltaic response for high density InGaAs coupled quantum dots

Chuang

Tzeng

et al. 2012

2012 38th IEEE Photovoltaic Specialists Conference

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In order to enhance absorption at infrared range for GaAs based solar cell, we insert the nine-layer of vertically coupled quantum dots (VCQDs) into the active layer. We fine modulated the GaAs spacer thickness of coupled Ino.75Gao. 2 5As QDs, and investigated the effects on photovoltaic response. For the open-circuit voltage (Voc), the values decreases from 0.61 V to 0.55 V as the spacer thickness (d) decreases from d= 15 nm to 5 nm for the nine-layer VCQDs solar cells. The reduction of Voc for the VCQDs solar cells is attributed to the accumulation of compressive strain energy in the active QD region. For the sample of d=10 nm shows the best performance of current density (Jsc-24 mA/cm 2 ) and efficiency (..,-10.6). The Jsc and ..,are increases by 55% and 112% more than the device without QDs, respectively.

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“…The excessive strain will induce defects to reduce the electrical output power. Previously, we reported the study on VCQDs structures of In 0.75 Ga 0.25 As QDs capped with In 0.10 Ga 0.90 As strain-reducing layers by molecular beam epitaxy (MBE) [6,7]. Strong coupling effects were observed by optical spectroscopies and transmission electron microscopy (TEM), as the spacer layer thickness of 5 nm was achieved.…”

Section: Introductionmentioning

confidence: 99%