Limits...
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.


PLE spectrum of QD2 recorded at 1.4 K with detection energy fixed.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3211504&req=5

Figure 8: PLE spectrum of QD2 recorded at 1.4 K with detection energy fixed.

Mentions: The PLE spectra of QD2 at 1.4 K are given in Figure 7 with the detection energy fixed at 1.1 eV (the maximum of the QD2 ground-state transition at 1.4 K). The energy of excited luminescence intensity was also displayed with respect to the detection energy (Edet). Due to the limited laser tuning range, the PLE spectra down to 1.236 eV (i.e., 136 meV above Edet) were recorded only. In contrast to the PLE results of smaller QDs, two resonance peaks were resolved clearly at 158 and 222 meV above the Edet. However, the PLE resonance at 222 meV is much broader than the one at a lower energy. When PLE spectra recorded at five different detection energies (as shown in Figure 8) were compared, two PLE resonances clearly shifted according to the change in detection energy. Therefore, there is reason to believe that these two resonances are due to the bound-to-bound absorption.


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)

PLE spectrum of QD2 recorded at 1.4 K with detection energy fixed.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 8: PLE spectrum of QD2 recorded at 1.4 K with detection energy fixed.
Mentions: The PLE spectra of QD2 at 1.4 K are given in Figure 7 with the detection energy fixed at 1.1 eV (the maximum of the QD2 ground-state transition at 1.4 K). The energy of excited luminescence intensity was also displayed with respect to the detection energy (Edet). Due to the limited laser tuning range, the PLE spectra down to 1.236 eV (i.e., 136 meV above Edet) were recorded only. In contrast to the PLE results of smaller QDs, two resonance peaks were resolved clearly at 158 and 222 meV above the Edet. However, the PLE resonance at 222 meV is much broader than the one at a lower energy. When PLE spectra recorded at five different detection energies (as shown in Figure 8) were compared, two PLE resonances clearly shifted according to the change in detection energy. Therefore, there is reason to believe that these two resonances are due to the bound-to-bound absorption.

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.