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Electronic Coupling in Nanoscale InAs/GaAs Quantum Dot Pairs Separated by a Thin Ga(Al)As Spacer.

Liu Y, Liang B, Guo Q, Wang S, Fu G, Fu N, Wang ZM, Mazur YI, Salamo GJ - Nanoscale Res Lett (2015)

Bottom Line: A thin Al0.5Ga0.5As barrier greatly changes the energy transfer process and the optical performance of the QD pairs.As a result, the QD PL intensity ratio shows different dependence on the intensity and wavelength of the excitation laser.These results provide useful information for fabrication and investigation of artificial QD molecules for implementing quantum computation applications.

View Article: PubMed Central - PubMed

Affiliation: College of Physics Science & Technology, Hebei University, Baoding, 071002, People's Republic of China.

ABSTRACT
The electronic coupling in vertically aligned InAs/GaAs quantum dot (QD) pairs is investigated by photoluminescence (PL) measurements. A thin Al0.5Ga0.5As barrier greatly changes the energy transfer process and the optical performance of the QD pairs. As a result, the QD PL intensity ratio shows different dependence on the intensity and wavelength of the excitation laser. Time-resolved PL measurements give a carrier tunneling time of 380 ps from the seed layer QDs to the top layer QDs while it elongates to 780 ps after inserting the thin Al0.5Ga0.5As barrier. These results provide useful information for fabrication and investigation of artificial QD molecules for implementing quantum computation applications.

No MeSH data available.


Related in: MedlinePlus

TRPL results for the SQDs and TQDs for both sample A and sample B
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Fig5: TRPL results for the SQDs and TQDs for both sample A and sample B

Mentions: The carrier coupling is further investigated through the temporal decay behavior for both samples at 10 K. For TRPL experiments, the samples are excited by a Ti:Sapphire mode-locked laser (780 nm, 78 MHz, 2.7 ps) and a C5680 Hamamatsu streak camera with the infrared-enhanced photocathode is used as detection system. The decay curves are measured with excitation intensity of ~4 × 107 photons/pulse for the QDs of both the seed and the top layers. As shown in Fig. 5, for both samples, the SQDs have a faster decay than the TQDs. This indicates that there is carrier tunneling between the two layers of QDs. However, the SQDs of sample A have a very short decay time (τ(E1) = 0.48 ns) in comparison with the TQDs(τ(E0) = 1.85 ns), while the SQDs of the sample B have a relatively long decay time (τ(E1) = 1.3 ns). The TRPL indicates the existence of a strong competition between tunneling and radiative recombination for the carriers inside the SQDs. Taking a simple model of the SQDs and the TQDs forming a three-level system, the measured PL decay time τt for the SQDs is approximately given by:Fig. 5


Electronic Coupling in Nanoscale InAs/GaAs Quantum Dot Pairs Separated by a Thin Ga(Al)As Spacer.

Liu Y, Liang B, Guo Q, Wang S, Fu G, Fu N, Wang ZM, Mazur YI, Salamo GJ - Nanoscale Res Lett (2015)

TRPL results for the SQDs and TQDs for both sample A and sample B
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4489975&req=5

Fig5: TRPL results for the SQDs and TQDs for both sample A and sample B
Mentions: The carrier coupling is further investigated through the temporal decay behavior for both samples at 10 K. For TRPL experiments, the samples are excited by a Ti:Sapphire mode-locked laser (780 nm, 78 MHz, 2.7 ps) and a C5680 Hamamatsu streak camera with the infrared-enhanced photocathode is used as detection system. The decay curves are measured with excitation intensity of ~4 × 107 photons/pulse for the QDs of both the seed and the top layers. As shown in Fig. 5, for both samples, the SQDs have a faster decay than the TQDs. This indicates that there is carrier tunneling between the two layers of QDs. However, the SQDs of sample A have a very short decay time (τ(E1) = 0.48 ns) in comparison with the TQDs(τ(E0) = 1.85 ns), while the SQDs of the sample B have a relatively long decay time (τ(E1) = 1.3 ns). The TRPL indicates the existence of a strong competition between tunneling and radiative recombination for the carriers inside the SQDs. Taking a simple model of the SQDs and the TQDs forming a three-level system, the measured PL decay time τt for the SQDs is approximately given by:Fig. 5

Bottom Line: A thin Al0.5Ga0.5As barrier greatly changes the energy transfer process and the optical performance of the QD pairs.As a result, the QD PL intensity ratio shows different dependence on the intensity and wavelength of the excitation laser.These results provide useful information for fabrication and investigation of artificial QD molecules for implementing quantum computation applications.

View Article: PubMed Central - PubMed

Affiliation: College of Physics Science & Technology, Hebei University, Baoding, 071002, People's Republic of China.

ABSTRACT
The electronic coupling in vertically aligned InAs/GaAs quantum dot (QD) pairs is investigated by photoluminescence (PL) measurements. A thin Al0.5Ga0.5As barrier greatly changes the energy transfer process and the optical performance of the QD pairs. As a result, the QD PL intensity ratio shows different dependence on the intensity and wavelength of the excitation laser. Time-resolved PL measurements give a carrier tunneling time of 380 ps from the seed layer QDs to the top layer QDs while it elongates to 780 ps after inserting the thin Al0.5Ga0.5As barrier. These results provide useful information for fabrication and investigation of artificial QD molecules for implementing quantum computation applications.

No MeSH data available.


Related in: MedlinePlus