Growth kinetics effects on self-assembled InAs��� InP quantum dots (original) (raw)
Related papers
Photoluminescence evolution in InAs/InP quantum dots grown by MOVPE
Self-assembled quantum dots of InAs have been grown on InP substrates by metal-organic vapour phase epitaxy. The effect of the growth temperature and the growth rate on the morphology and the optical properties of the quantum dots is studied using atomic force microscopy and photoluminescence spectroscopy. The spectral shape of the low temperature photoluminescence depends strongly on the growth conditions. A single peak, observed at a high growth rates, develops into two o r even three distinct peaks for different samples grown at progressively lower growth rates. These findings weakly correlate with the observed size distribution of the quantum dots although the role of arsenic/phosphorous exchange at the Group-V sites may also be important. The temperature dependence of the photoluminescence spectra for the samples with a single peak is also discussed.
Journal of Electronic Materials, 2001
We report the characteristics of InP self-assembled quantum dots embedded in In 0.5 Al 0.5 P on GaAs substrates grown by metalorganic chemical vapor deposition. The InP quantum dots show increased average dot sizes and decreased dot densities, as the growth temperature increases from 475°C to 600°C with constant growth time. Above the growth temperature of 600°C, however, dramatically smaller and densely distributed self-assembled InP quantum dots are formed. The small InP quantum dots grown at 650°C are dislocation-free "coherent" regions with an average size of ~20 nm (height) and a density of ~1.5 × 10 8 mm -2 . These InP quantum dots have a broad range of luminescence corresponding to red or orange in the visible spectrum.
Photoluminescence of InAs Self-Organized Quantum Dots Formation on InP Substrate by MOCVD
Optical and Quantum Electronics, 1998
In this letter, we present results of photoluminescence (PL) emission from single-layer and multilayer InAs self-organized quantum dots (QDs), which were grown on (001) InP substrate. The room temperature PL peak of the single-layer QDs locates at 1608 nm, and full width at half-maximum (FWHM) of the PL peak is 71 meV. The PL peak of the multilayer QDs locates at 1478 nm, PL intensity of which is stronger than that of single-layer QDs. The single-layer QD PL spectra also display excited state emission and state filling as the excitation intensity is increased. Low temperature PL spectra show a weak peak between the peaks of QDs and wetting layer (WL), which suggests the recombination between electrons in the WL and holes in the dots.
Journal of Crystal Growth, 2003
The surface morphology changes associated with the formation of InAs/InP(3 1 1)B quantum dots grown according to a proposed growth procedure (double cap) have been investigated using atomic force microscopy (AFM). We show that the deposit of an InP capping layer thinner than the highest dot, followed by the annealing under phosphorous overpressure, leads to the smoothing of the growth front. It induces a drastic reduction of the dot height and of its dispersion. Transmission electron microscopy and photoluminescence experiments show a clear correlation between the QD height and the deposited InP layer thickness. Using this modified capping growth process, a 1.55 mm emission wavelength with a narrower PL linewidth (50 meV) is achieved. Finally, we report ground state laser emission from QDs at 1.52 mm, which supports the DC process for the fabrication of QD devices emitting in the 1.5 mm range. r
Another origin of bimodal size distribution in InAs self-assembled quantum dots
2005
The evolution of InAs quantum dots grown on InP substrates by metal-organic vapour phase epitaxy is studied as a function of InAs coverage. Under specific growth conditions, the onset of the two-to three-dimensional transition is seen to proceed via two distinct pathways: through (i) an abrupt appearance of quantum dots as expected in the usual Stranski-Krastanov growth picture and (ii) a continuous evolution of small surface features into well developed quantum dots. The average size of the features in both these families increases with coverage, leading to a bimodal distribution in dot sizes at an intermediate stage of growth evolution that eventually becomes a unimodal distribution as more material is deposited. Complementary information obtained from independent measurements of photoluminescence spectra and surface morphology is correlated and is found to be independently consistent with the picture of growth proposed.
Quantum Dots Grown In-Situ by MOVPE: Sizes, Densities and Optical Properties
1997
This paper focuses on the strain-induced self-organization, or \self-assembly" e ect, producing quantum dots. Particularly the following aspects will be addressed: (i) the phenomenology of the 2D-3D morphology transition, (ii) the e ects of materials choices and growth conditions on density, size and homogeneity of dots, (iii) manipulations to get laterally aligned and vertically stacked dot structures and (iv) optical properties of free-standing and buried dots of InP grown on GaInP/GaAs(001). Free-standing as well as buried dots of InP on GaInP/GaAs show luminescence and quantum con nement e ects which depend on the size of the islands. Luminescence arising from single dots will be demonstrated.
Journal of Electronic Materials, 2003
Quasi zero-dimensional semiconductor quantumdot (QD) structures having delta-function distribution of the density of states and the discrete energy levels of carriers induced by three-dimensional quantum confinement provide the potential for more efficient light emitting diodes and lasers employing quantum dots as an active medium. 1,2,3 The direct growth technique of coherently strained defect-free self-assembled quantum dots (SAQDs) 4 on planar substrates using the coherent Stranski-Krastanov growth mode 5 offers the potential to realize quantum-dot-based devices with improved performance, which has been theoretically predicted. 1 Also, due to its intrinsic strain-induced growth mode, self-assembled quantum dot growth can overcome the limitations of the requirement for lattice matching between the substrate and the active quantumdot layer, making it possible to produce bandgapengineered high-quality materials, hence, providing a wider wavelength range for high-efficiency light emitters. Especially, III-Phosphide SAQD structures can be used for light emitters operating in the visible spectral region, depending on the size and composition of the quantum dots. Considering the "blue shift" effect of the emission from the SAQDs induced from multiple orders of quantum confinement and compressive strain on QDs, binary and ternary III-Phosphide SAQD structures have a potential to extend the wavelength of light emitters to the yellow or green spectral regions.
Influence of surface reconstructions on the shape of InAs quantum dots grown on InP (001)
2008
Growth mechanisms controlling the shape of InAs quantum dots grown by solid source MBE on InP(001) are studied. InAs surface reconstructions play an important role to get more isotropic quantum dots rather than elongated quantum dashes. Dash to dot shape transition is also demonstrated with postgrowth treatments that change InAs surface reconstructions. Properties of such single InAs/InP quantum dots on low density samples are finally evaluated with microphotoluminescence and cathodoluminescence studies. Index Terms-Self-organized growth, InAs/InP quantum dots; solid source MBE; shape transition; surface reconstructions; single quantum dot
Self-assembling InAs and InP quantum dots for optoelectronic devices
Thin Solid Films, 2000
Stranski-Krastanov growth in molecular beam epitaxy allows the preparation of self assembling InAs and InP quantum dots on GaAs and Ga0,521no,4,P buffer layers, respectively. InAs dots in GaAs prepared by slow growth rates and low temperature overgrowth provide intense photoluminescence at the technologically important wavelength of 1.3 p,m at room temperature. Strain induced vertical alignment, size modification and material interdiffusion for stacked dot layers are studied. A blue shift of the ground state transition energy is observed for the slowly deposited stacked InAs dots. This is ascribed to enhanced strain driven intermixing in vertically aligned islands. For very small densely stacked InP and InAs dots the reduced confinement shift causes a red shift of the ground state emission. The InP quantum dots show intense and narrow photoluminescence at room temperature in the visible red spectral range. First InP/Ga0,521no,4,P quantum dot injection lasers are prepared using threefold stacked InP dots. We observe lasing at room temperature in the wavelength range between 690-705 nm depending on the size of the stacked InP dots.
Semiconductor Science and Technology, 2002
We report on an optical study of InAs quantum dots grown on an InP(311)B substrate, and lasing at 1.55 µm wavelength. A new growth technique, called the 'double-cap' technique, has been used to reach 1.55 µm at 300 K. The samples are characterized at low temperature and room temperature by continuous-wave and time-resolved photoluminescence techniques. The wetting layer emission and a dot excited state emission are clearly observed for the first time in this kind of dot, and the results are consistent with theoretical calculations. At the same time, these structures seem to have a better capture efficiency.