“…However, these abnormalities disappear progressively after post-growth intermixing processes in the InAs/InGaAs/GaAs QD heterostructures as shown by Ilahi et al [ 9 ]. Heterostructures similar to those of the present study have been investigated for their efficiency in photovoltaic applications by Sayari et al [ 10 ]. Many models have been proposed during the last decades, such as the Passler, Vina, and Varshni one.…”
Section: Introductionmentioning
confidence: 80%
“… Fig. 2 Real ( ϵ 1 ) ( dashed red line ) and imaginary ( ϵ 2 ) ( solid blue line ) parts of dielectric functions of the InAs/InGaAs QD heterostructure obtained from SE measurements [ 10 ] …”
Section: Resultsmentioning
confidence: 99%
“…b RHEED patterned after growth of 2.5 ML of InAs (three-dimensional growth). c RHEED patterned during growth of 5 nm InGaAs (two-dimensional growth) [ 10 ] …”
This paper reports on experimental and theoretical investigations of atypical temperature-dependent photoluminescence properties of multi-stacked InAs quantum dots in close proximity to InGaAs strain-relief underlying quantum well. The InAs/InGaAs/GaAs QD heterostructure was grown by solid-source molecular beam epitaxy (SS-MBE) and investigated via photoluminescence (PL), spectroscopic ellipsometry (SE), and picosecond time-resolved photoluminescence. Distinctive double-emission peaks are observed in the PL spectra of the sample. From the excitation power-dependent and temperature-dependent PL measurements, these emission peaks are associated with the ground-state transition from InAs QDs with two different size populations. Luminescence measurements were carried out as function of temperature in the range of 10–300 K by the PL technique. The low temperature PL has shown an abnormal emission which appeared at the low energy side and is attributed to the recombination through the deep levels. The PL peak energy presents an anomalous behavior as a result of the competition process between localized and delocalized carriers. We propose the localized-state ensemble model to explain the usual photoluminescence behaviors. The quantitative study shows that the quantum well continuum states act as a transit channel for the redistribution of thermally activated carriers. We have determined the localization depth and its effect on the application of the investigated heterostructure for photovoltaic cells. The model gives an overview to a possible amelioration of the InAs/InGaAs/GaAs QDs SCs properties based on the theoretical calculations.
“…However, these abnormalities disappear progressively after post-growth intermixing processes in the InAs/InGaAs/GaAs QD heterostructures as shown by Ilahi et al [ 9 ]. Heterostructures similar to those of the present study have been investigated for their efficiency in photovoltaic applications by Sayari et al [ 10 ]. Many models have been proposed during the last decades, such as the Passler, Vina, and Varshni one.…”
Section: Introductionmentioning
confidence: 80%
“… Fig. 2 Real ( ϵ 1 ) ( dashed red line ) and imaginary ( ϵ 2 ) ( solid blue line ) parts of dielectric functions of the InAs/InGaAs QD heterostructure obtained from SE measurements [ 10 ] …”
Section: Resultsmentioning
confidence: 99%
“…b RHEED patterned after growth of 2.5 ML of InAs (three-dimensional growth). c RHEED patterned during growth of 5 nm InGaAs (two-dimensional growth) [ 10 ] …”
This paper reports on experimental and theoretical investigations of atypical temperature-dependent photoluminescence properties of multi-stacked InAs quantum dots in close proximity to InGaAs strain-relief underlying quantum well. The InAs/InGaAs/GaAs QD heterostructure was grown by solid-source molecular beam epitaxy (SS-MBE) and investigated via photoluminescence (PL), spectroscopic ellipsometry (SE), and picosecond time-resolved photoluminescence. Distinctive double-emission peaks are observed in the PL spectra of the sample. From the excitation power-dependent and temperature-dependent PL measurements, these emission peaks are associated with the ground-state transition from InAs QDs with two different size populations. Luminescence measurements were carried out as function of temperature in the range of 10–300 K by the PL technique. The low temperature PL has shown an abnormal emission which appeared at the low energy side and is attributed to the recombination through the deep levels. The PL peak energy presents an anomalous behavior as a result of the competition process between localized and delocalized carriers. We propose the localized-state ensemble model to explain the usual photoluminescence behaviors. The quantitative study shows that the quantum well continuum states act as a transit channel for the redistribution of thermally activated carriers. We have determined the localization depth and its effect on the application of the investigated heterostructure for photovoltaic cells. The model gives an overview to a possible amelioration of the InAs/InGaAs/GaAs QDs SCs properties based on the theoretical calculations.
“…This structure leads to decreasing the energy transition, then increasing the wavelength which increase the response of the QDs solar cells [37,38]. Additionally, in the case of the high index substrate, the present piezoelectric field can efficiently extract the photogenerated carriers by exceeding the critical electric field for optimized carrier collection [39].…”
Section: Single Qd-in-well Of Inas Qds Imbedded In In X Ga 1−x As Witmentioning
“…The implementation of GaAsSb/InAs/GaAs QDs in photovoltaic devices will be the focus of this chapter. The application of thin CLs to QD solar cells has hardly been investigated thus far [207,208] for what the novel use of GaAsSb CLs could bring additional advantages. The ability to tune and thereby extend the QD ground state to longer wavelengths is expected to provide QD solar cells with an additional infrared contribution to the PC.…”
Quantum-dot (QD) technology has become a very transversal technology finding application in an increasing number of scientific and industrial fields. At the forefront of this development is the well-studied InAs/GaAs QD system. However, the limitations imposed by the fixed InAs-GaAs band offsets and by the difficulties to control the QD morphology due to the capping process still difficult the precise control of QD band structure that would allow the required design in different applications. The use of a certain capping layer (CL) material different than GaAs has been particularly employed to tune the ground state energy of InAs/GaAs QDs through strain and band structure engineering, so achieving the longwavelength telecommunication windows as one of the most pursued targets. This work is mainly focused on the achievement of a higher tunability of the properties of InAs/GaAs QDs by the application of thin GaAs(Sb)(N) CLs and the optimization of the capping process in order to improve their suitability to any optoelectronic device, and more in particular to laser diodes and solar cells. GaAs(Sb)(N)/InAs/GaAs QDs are a highly versatile system in which the use of Sb and N allows for the tunability of the QD ground state while providing a huge degree of freedom regarding the QD-CL band-alignment, according to the requirements of the field of application. quieren, por lo tanto, enfoques alternativos con el fin de mejorar la eficiencia de conversión. En particular, se demuestra que parámetros como la profundidad del pozo de potencial en el CL, su espesor, y su estructura, así como el alineamiento de bandas resultante, juegan un papel importante en la extracción y el transporte de portadores en células solares de QD.
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