Influence of the excitation density and temperature on the optical properties of type I InAs/GaAsSb quantum dots

The CdSe, type-II CdSe/CdTe core/shell and type-II/type-I CdSe/CdTe/ZnS core/shell/shell quantum dots (QDs) were successfully synthesized in a noncoordinating solvent. The phonon characterizations, optical properties and structures of the synthesized QDs were characterized by Raman scattering (RS) spectra, photoluminescence (PL) spectroscopy, PL-decay lifetime, absorption spectroscopy (Abs), and X-ray diffraction (XRD). The growth of QDs was monitored by using RS, which demonstrated the formation of correct of the core/shell and core/shell/shell structures. Observation results from XRD reveal that all QDs crystallize in the cubic phase with zinc-blende structure. The typical characteristics of spatially indirect recombination for type-II QDs were observed through Abs and PL spectroscopy. The ZnS shell significantly enhanced the PL quantum yeild (QY), the optical durability, the chemical stability and separating CdSe/CdTe QDs from the surroundings. The effect of excitation power on the PL properties of the CdSe core, CdSe/CdTe and CdSe/CdTe/ZnS QDs has been investigated.

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Optical properties of type-I and II quantum dots

Brazilian Journal of Physics ◽

10.1590/s0103-97332004000400004 ◽

2004 ◽

Vol 34 (2b) ◽

pp. 555-559 ◽

Cited By ~ 3

Author(s):

F. Iikawa ◽

M. P. F. Godoy ◽

M. K. K. Nakaema ◽

M. J. S. P. Brasil ◽

M. Z. Maialle ◽

...

Keyword(s):

Quantum Dots ◽

Optical Properties ◽

Type I

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Size and Shape Evolution of GaAsSb-Capped InAs/GaAs Quantum Dots: Dependence on the Sb Content

Crystals ◽

10.3390/cryst9100530 ◽

2019 ◽

Vol 9 (10) ◽

pp. 530

Author(s):

Khairiah Alshehri ◽

Abdelmajid Salhi ◽

Niyaz Ahamad Madhar ◽

Bouraoui Ilahi

Keyword(s):

Quantum Dots ◽

Optical Properties ◽

Numerical Evaluation ◽

Band Alignment ◽

Accurate Estimation ◽

Type I ◽

Shape Evolution ◽

Photoluminescence Spectra ◽

Size And Shape ◽

Shape And Size

Capping InAs/GaAs quantum dots (QDs) with a thin GaAsSb layer alters the QDs structural properties, leading to considerable changes in their optical properties. The increase of the Sb content induces a redshift of the emission energies, indicating a change in the buried QDs shape and size. The presence of well-defined ground- and excited-state emission bands in all the photoluminescence spectra allow an accurate estimation of the buried QDs size and shape by numerical evaluation and tuning of the theoretical emission energies. For an Sb content below 14%, the QDs are found to have a type I band alignment with a truncated height pyramidal form. However, for higher Sb content (22%), the QDs are present in a full pyramidal shape. The observed behavior is interpreted in terms of increasing prevention of InAs QDs decomposition with increasing the Sb content in the cap layer.

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