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Effects of crossed states on photoluminescence excitation spectroscopy of InAs quantum dots.

Shih CI, Lin CH, Lin SC, Lin TC, Sun KW, Voskoboynikov OA, Lee CP, Suen YW - Nanoscale Res Lett (2011)

Bottom Line: Results from the PLE spectroscopy at low temperature and under a high magnetic field (up to 14 T) were compared.Our findings show that the profile of the PLE resonances associated with the bound transitions disintegrated and broadened.The degree of spectral linewidth broadening was larger for the excited state in smaller QDs because of the higher crossed joint density of states and scattering rate.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Nanoscience, National Chung Hsing University, 250 Kuo Kuang Rd,, Taichung 402, Taiwan. ysuen@phys.nchu.edu.tw.

ABSTRACT
In this report, the influence of the intrinsic transitions between bound-to-delocalized states (crossed states or quasicontinuous density of electron-hole states) on photoluminescence excitation (PLE) spectra of InAs quantum dots (QDs) was investigated. The InAs QDs were different in size, shape, and number of bound states. Results from the PLE spectroscopy at low temperature and under a high magnetic field (up to 14 T) were compared. Our findings show that the profile of the PLE resonances associated with the bound transitions disintegrated and broadened. This was attributed to the coupling of the localized QD excited states to the crossed states and scattering of longitudinal acoustical (LA) phonons. The degree of spectral linewidth broadening was larger for the excited state in smaller QDs because of the higher crossed joint density of states and scattering rate.

No MeSH data available.


Excitation power dependent PL spectra of QD2 at 77 K.
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Figure 3: Excitation power dependent PL spectra of QD2 at 77 K.

Mentions: Figures 2 and 3 show the excitation power dependence of the PL spectra at liquid nitrogen temperature for the QD1 and QD2 samples, respectively. The state filling of the excited state transitions can be observed for the QDs by increasing the pumping power. In Figure 2, the ground-state energy as well as the barrier and WL emissions of the QD1 are observed clearly at around 1.227, 1.509, and 1.422 eV, respectively. Due to the smaller size of the dots, only one excited state (1Pe → 1Ph transition) was identified and contributed to the PL spectra at 70 meV above the ground state. For the dots with a larger diameter (QD2), there are three excited states contributed to the PL spectrum (as shown in Figure 3) at 86, 161, and 213 meV above the ground state other than the emission peaks from the barrier and the WL.


Effects of crossed states on photoluminescence excitation spectroscopy of InAs quantum dots.

Shih CI, Lin CH, Lin SC, Lin TC, Sun KW, Voskoboynikov OA, Lee CP, Suen YW - Nanoscale Res Lett (2011)

Excitation power dependent PL spectra of QD2 at 77 K.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211504&req=5

Figure 3: Excitation power dependent PL spectra of QD2 at 77 K.
Mentions: Figures 2 and 3 show the excitation power dependence of the PL spectra at liquid nitrogen temperature for the QD1 and QD2 samples, respectively. The state filling of the excited state transitions can be observed for the QDs by increasing the pumping power. In Figure 2, the ground-state energy as well as the barrier and WL emissions of the QD1 are observed clearly at around 1.227, 1.509, and 1.422 eV, respectively. Due to the smaller size of the dots, only one excited state (1Pe → 1Ph transition) was identified and contributed to the PL spectra at 70 meV above the ground state. For the dots with a larger diameter (QD2), there are three excited states contributed to the PL spectrum (as shown in Figure 3) at 86, 161, and 213 meV above the ground state other than the emission peaks from the barrier and the WL.

Bottom Line: Results from the PLE spectroscopy at low temperature and under a high magnetic field (up to 14 T) were compared.Our findings show that the profile of the PLE resonances associated with the bound transitions disintegrated and broadened.The degree of spectral linewidth broadening was larger for the excited state in smaller QDs because of the higher crossed joint density of states and scattering rate.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Nanoscience, National Chung Hsing University, 250 Kuo Kuang Rd,, Taichung 402, Taiwan. ysuen@phys.nchu.edu.tw.

ABSTRACT
In this report, the influence of the intrinsic transitions between bound-to-delocalized states (crossed states or quasicontinuous density of electron-hole states) on photoluminescence excitation (PLE) spectra of InAs quantum dots (QDs) was investigated. The InAs QDs were different in size, shape, and number of bound states. Results from the PLE spectroscopy at low temperature and under a high magnetic field (up to 14 T) were compared. Our findings show that the profile of the PLE resonances associated with the bound transitions disintegrated and broadened. This was attributed to the coupling of the localized QD excited states to the crossed states and scattering of longitudinal acoustical (LA) phonons. The degree of spectral linewidth broadening was larger for the excited state in smaller QDs because of the higher crossed joint density of states and scattering rate.

No MeSH data available.