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Strong enhancement of terahertz emission from GaAs in InAs/GaAs quantum dot structures
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View: Figures


Image of FIG. 1.
FIG. 1.

Normalized 77 K PL of the SLQD and MLQD samples. Results reveal that more uniform and larger-sized QD structures dominate the MLQD. The inset shows a comparison of the normalized broadband terahertz radiation power from the MLQD, SLQD, -InAs, -InAs, and reference SI- and UD-GaAs samples. Both QD wafers emit more strongly than -InAs and the MLQD radiation power reaches up to 70% that of -InAs.

Image of FIG. 2.
FIG. 2.

(a) The excitation wavelength spectra comparison for the QD samples, -InAs, and UD-GaAs. The QD samples’ terahertz emission is due photocarriers from UD GaAs absorption and not from the QD structures. (b) The azimuthal angle dependence of the terahertz radiation power in the QD samples show the dominance of an angularly independent surge current mechanism as in the reference samples, surmised to be due to the transient current as the photocarriers are swept across the strain field of the GaAs/InAs interface region.

Image of FIG. 3.
FIG. 3.

(a) Excitation fluence dependence comparison for the samples that were studied. At low fluence excitation, the MLQD emission is comparable to that of -InAs. (b) The terahertz emission spectra show that the MLQD terahertz bandwidth is similar to the -InAs. The presence of Fabry–Perot oscillations is attributed to GaAs being transparent at terahertz frequencies and to the multilayer structures in the QD samples. It can be noted that both the MLQD and the SLQD emit more strongly than -InAs.


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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Strong enhancement of terahertz emission from GaAs in InAs/GaAs quantum dot structures