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Optical characterization of In-flushed InAs/GaAs quantum dots emitting a broadband spectrum with multiple peaks at ~1 μm.

Kitamura S, Senshu M, Katsuyama T, Hino Y, Ozaki N, Ohkouchi S, Sugimoto Y, Hogg RA - Nanoscale Res Lett (2015)

Bottom Line: By using the In-flush technique for setting the height of self-assembled InAs QDs, we have tuned the emission wavelength of InAs QDs to the ~1 μm regime, which can be utilized as a non-invasive and deeply penetrative probe for biological and medical imaging systems.The controlled emission exhibited a broadband spectrum comprising multiple peaks with an interval of approximately 30 meV.This feature can be advantageous for realizing a broadband light source centered at the ~1 μm regime, which is especially suitable for the non-invasive cross-sectional biological and medical imaging system known as optical coherence tomography.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Engineering, University of Fukui, Fukui, 910-8507 Japan.

ABSTRACT
We investigated optical properties of In-flushed InAs quantum dots (QDs) grown on a GaAs substrate by molecular beam epitaxy. By using the In-flush technique for setting the height of self-assembled InAs QDs, we have tuned the emission wavelength of InAs QDs to the ~1 μm regime, which can be utilized as a non-invasive and deeply penetrative probe for biological and medical imaging systems. The controlled emission exhibited a broadband spectrum comprising multiple peaks with an interval of approximately 30 meV. We examined the origin of the multiple peaks using spectral and time-resolved photoluminescence, and concluded that it is attributed to monolayer step fluctuations in the height of the In-flushed QDs. This feature can be advantageous for realizing a broadband light source centered at the ~1 μm regime, which is especially suitable for the non-invasive cross-sectional biological and medical imaging system known as optical coherence tomography.

No MeSH data available.


Related in: MedlinePlus

Photoexcitation power dependence of RT–PL obtained from a as-grown InAs QDs and b In-flushed QDs. The excitation power densities were approximately 100 (black), 200 (blue), and 300 (red) W/cm2. c Schematic drawing of ML-step height fluctuations of the In-flushed QDs
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Fig3: Photoexcitation power dependence of RT–PL obtained from a as-grown InAs QDs and b In-flushed QDs. The excitation power densities were approximately 100 (black), 200 (blue), and 300 (red) W/cm2. c Schematic drawing of ML-step height fluctuations of the In-flushed QDs

Mentions: Figure 3a, b shows the RT–PL spectra obtained using various photoexcitation powers (approximately 100, 200, and 300 W/cm2) from the as-grown QDs and the In-flushed QDs, respectively. As shown in Fig. 3a, the as-grown QDs emit a dominant peak at approximately 1.02 eV (λ = 1.22 μm) and an additional peak at approximately 1.09 eV (λ = 1.13 μm). These emission peaks originate from discrete states due to the quantum confinement of electrons and holes in QDs; the lower energy emission arises from the recombination between the fundamental ground states (GS) of electrons and holes, and the higher energy emission arises from the recombination between excited states (ES). The inhomogeneous broadening of the peaks originate from the size and composition distributions of the QDs. The full width at half maximum (FWHM) of the GS emission is approximately 36 meV. As seen in the normalized PL spectra, the different excitation power dependence between the GS and ES emissions is attributed to the state filling of the GS with photogenerated carriers, resulting in a saturation of GS emission intensity and a subsequent increase in ES emission intensity.Fig. 3


Optical characterization of In-flushed InAs/GaAs quantum dots emitting a broadband spectrum with multiple peaks at ~1 μm.

Kitamura S, Senshu M, Katsuyama T, Hino Y, Ozaki N, Ohkouchi S, Sugimoto Y, Hogg RA - Nanoscale Res Lett (2015)

Photoexcitation power dependence of RT–PL obtained from a as-grown InAs QDs and b In-flushed QDs. The excitation power densities were approximately 100 (black), 200 (blue), and 300 (red) W/cm2. c Schematic drawing of ML-step height fluctuations of the In-flushed QDs
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4446289&req=5

Fig3: Photoexcitation power dependence of RT–PL obtained from a as-grown InAs QDs and b In-flushed QDs. The excitation power densities were approximately 100 (black), 200 (blue), and 300 (red) W/cm2. c Schematic drawing of ML-step height fluctuations of the In-flushed QDs
Mentions: Figure 3a, b shows the RT–PL spectra obtained using various photoexcitation powers (approximately 100, 200, and 300 W/cm2) from the as-grown QDs and the In-flushed QDs, respectively. As shown in Fig. 3a, the as-grown QDs emit a dominant peak at approximately 1.02 eV (λ = 1.22 μm) and an additional peak at approximately 1.09 eV (λ = 1.13 μm). These emission peaks originate from discrete states due to the quantum confinement of electrons and holes in QDs; the lower energy emission arises from the recombination between the fundamental ground states (GS) of electrons and holes, and the higher energy emission arises from the recombination between excited states (ES). The inhomogeneous broadening of the peaks originate from the size and composition distributions of the QDs. The full width at half maximum (FWHM) of the GS emission is approximately 36 meV. As seen in the normalized PL spectra, the different excitation power dependence between the GS and ES emissions is attributed to the state filling of the GS with photogenerated carriers, resulting in a saturation of GS emission intensity and a subsequent increase in ES emission intensity.Fig. 3

Bottom Line: By using the In-flush technique for setting the height of self-assembled InAs QDs, we have tuned the emission wavelength of InAs QDs to the ~1 μm regime, which can be utilized as a non-invasive and deeply penetrative probe for biological and medical imaging systems.The controlled emission exhibited a broadband spectrum comprising multiple peaks with an interval of approximately 30 meV.This feature can be advantageous for realizing a broadband light source centered at the ~1 μm regime, which is especially suitable for the non-invasive cross-sectional biological and medical imaging system known as optical coherence tomography.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Engineering, University of Fukui, Fukui, 910-8507 Japan.

ABSTRACT
We investigated optical properties of In-flushed InAs quantum dots (QDs) grown on a GaAs substrate by molecular beam epitaxy. By using the In-flush technique for setting the height of self-assembled InAs QDs, we have tuned the emission wavelength of InAs QDs to the ~1 μm regime, which can be utilized as a non-invasive and deeply penetrative probe for biological and medical imaging systems. The controlled emission exhibited a broadband spectrum comprising multiple peaks with an interval of approximately 30 meV. We examined the origin of the multiple peaks using spectral and time-resolved photoluminescence, and concluded that it is attributed to monolayer step fluctuations in the height of the In-flushed QDs. This feature can be advantageous for realizing a broadband light source centered at the ~1 μm regime, which is especially suitable for the non-invasive cross-sectional biological and medical imaging system known as optical coherence tomography.

No MeSH data available.


Related in: MedlinePlus