InAs quantum dots grown on InAlGaAs lattice matched to InP (original) (raw)
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Optical properties of InAs quantum dots: Common trends
1999
We compare results obtained in several tens of samples grown by molecular-beam epitaxy under different growth conditions with a substantial amount of data found in the literature. By plotting the photoluminescence PL peak energy (E p ) of the quantum dot QD bands as a function of the nominal thickness of deposited InAs L three regions are clearly evidenced in the (E p ,L) plane. Below the so-called critical thickness (L c ), three-dimensional precursors of QD's show a smooth dependence of their emission energy on L. Around L c , QD's show a steep dependence of E p on L, independent of the growth conditions. Finally, for L2 ML one observes a saturation of the PL energy. This energy assumes only discrete values dependent on the growth conditions, which is attributed to the aggregation of quantum dots with different faceting. S0163-18299901311-9 PHYSICAL REVIEW B 15 MARCH 1999-I VOLUME 59, NUMBER 11 PRB 59 0163-1829/99/5911/76204/$15.00 7620
Spectroscopy of the electronic states in InAs quantum dots grown on InxAl1-xAs/InP(001
Physical Review B, 2004
We have investigated optical properties of high-density InAs self-assembled quantum dots ͑QDs͒ in an In x Al 1Ϫx As matrix, lattice matched to an InP ͑001͒ substrate. The weak lattice mismatch (ϳ3%) results in a 90% coverage of the In x Al 1Ϫx As surface with InAs QDs. By means of interband and intraband spectroscopies crossed with atomic force microscopy ͑AFM͒ measurements, we have determined that the InAs QDs optical properties depend on the deposited amount of InAs. Photoinduced absorption spectroscopy has been used to investigate midinfrared intraband absorptions. For three monolayers ͑ML͒ InAs deposit thickness, just above two-dimensional ͑2D͒/3D growth mode transition ͑2.5 ML͒, the islands form as isolated elliptical dots elongated along the ͓110͔ direction and exhibit intraband resonances polarized either along the ͓110͔ or the ͓110͔ direction. For thicker deposition (Ͼ3 ML), InAs islands form chains of elliptical dots along the ͓110͔ direction where the quantum confinement is lost, resulting in a quantum-wire-like behavior. In this paper, we also report on photoluminescence and photocurrent spectroscopies, in order to get insight into the InAs/In x Al 1Ϫx As island band structure. These experimental results are in good agreement with that of a multiband k•p model.
Applied Surface Science, 2002
Self-assembled InAs quantum dots (QDs) on In 0.52 Al 0.48 As layer lattice matched to (1 0 0) InP substrates have been grown by molecular beam epitaxy (MBE) and evaluated by transmission electron microscopy (TEM) and photoluminescence (PL). TEM observations indicate that defect-free InAs QDs can be grown to obtain emissions over the technologically important 1.3-1.55 mm region. The PL peak positions for the QDs shift to low energy as the InAs coverage increases, corresponding to increase in QD size. The room temperature PL peak at 1.58 mm was observed from defect-free InAs QDs with average dot height of 3.6 nm.
The formation of InAs quantum dots by Stransky-Krastanow method on (311)B InP substrates has been studied. On Al0.48In0.52As alloy lattice matched on InP, large changes of the quantum dot structural characteristics have been observed as a function of the amount of InAs deposited and of the Arsenic pressure during the InAs quantum dot formation. Small quantum dots (minimum diameter = 20 nm) in very high density (1.3 x1011 quantum dots per cm2) have been achieved in optimized growth conditions. These results are interpreted from the strong strain field interaction through the substrate at high density and from the InAs surface energy evolutions with the Arsenic pressure. The effect on quantum dot characteristics of the arsenic pressure during the growth of Al0.48In0.52As buffer layers has been also investigated. Despite the importance of this parameter on the Al0.48In0.52As clustering, weak changes have been observed.
OMVPE of InAs quantum dots on an InGaP surface
Materials Science in Semiconductor Processing, 2013
The organometallic vapor phase epitaxy of InAs quantum dots has been investigated by comparing the effect the underlying surface has on the quantum dot physical characteristics. Atomic force microscopy measurements were used to identify the InAs QDs coalesce to significantly larger size when deposited on an InGaP surface compared to a GaAs surface. Quantitative assessment of the total QD volume on different surfaces such as GaAs, InGaP, and GaAsP implicates the role of indium in the underlying surface for the increase in QD size on InGaP surfaces.
Journal of Crystal Growth, 2004
Self-assembled InAs quantum dots (QDs) with In 0.15 Ga 0.85 As were grown by a molecular beam epitaxy and their optical properties were investigated by photoluminescence (PL) spectroscopy. For InAs QDs inserted in an asymmetric In 0.15 Ga 0.85 As quantum well, the emission peak position of QDs is 1.30 mm (0.953 eV) with narrower PL linewidth and larger energy-level spacing between the ground states and the first excited states compared to those of QDs embedded in a GaAs matrix. While the room temperature PL yield for InAs QDs in a GaAs matrix was reduced by 1/99 from that measured at 18 K, the reduction in PL yield for InAs QDs, grown on a 1 nm In 0.15 Ga 0.85 As layer, with a 6 nm In 0.15 Ga 0.85 As overgrowth layer was only 1/27. Also, using the In 0.15 Ga 0.85 As overgrowth layer significantly reduced the temperature sensitivity of the peak energy for InAs QDs. The relatively better temperature PL characteristics of the QDs with In 0.15 Ga 0.85 As, as well as the ability to control the emission peak position and the energy-level spacing are interesting and important for device applications. r
Structural and physical properties of InAlAs quantum dots grown on GaAs
Physica B-condensed Matter, 2018
Quantum dots (QDs), which have particular physical properties due to the three dimensions confinement effect, could be used in many advanced optoelectronic applications. We investigated the properties of InAlAs/AlGaAs QDs grown by molecular beam epitaxy on GaAs/Al 0.5 Ga 0.5 As layers. The optical properties of QDs were studied by low-temperature photoluminescence (PL). Two bandgap transitions corresponding to the X-S h and X-P h energy structure were observed. The QDs structure was investigated using high-resolution X-ray diffraction (HRXRD) and high-resolution transmission electron microscopy (HRTEM). HRXRD investigations showed that the layers grew epitaxially on the substrate, with no relaxation. HRTEM investigations confirmed the epitaxial nature of the grown structures. In addition, it was revealed that the In atoms aggregated in some prismatic regions, forming areas of high In concentration, that were still in perfect registry with the substrate.
Optical properties of self-assembled InAs quantum dots on high-index GaAs substrates
Superlattices and Microstructures, 1997
In this work we have studied the optical properties of InAs quantum dots (QDs) grown by molecular-beam epitaxy on GaAs (211)A, on (n11)A/B (where n is 1, 5 and 7), and on reference (100) substrates. Investigation of orientation and polarity effects by means of photoluminescence (PL) are also presented. The PL spectra reveal interesting differences in amplitude, integral luminescence, peak position and peak shape. The PL temperature dependence indicates an additional lateral confinement on (100), (n11)B, (211)A and (111)A surfaces. Our results also show an enhancement of the QD onset thermal quenching energy by a factor of ∼ 3 for these orientations. In contrast, the structures grown on (711)A and (511)A surfaces do not exhibit QD formation.