Photoluminescence evolution in InAs/InP quantum dots grown by MOVPE (original) (raw)
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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.
Growth kinetics effects on self-assembled InAs��� InP quantum dots
2005
A systematic manipulation of the morphology and the optical emission properties of MOVPE grown ensembles of InAs/InP quantum dots is demonstrated by changing the growth kinetics parameters. Under non-equilibrium conditions of a comparatively higher growth rate and low growth temperature, the quantum dot density, their average size and hence the peak emission wavelength can be tuned by changing efficiency of the surface diffusion (determined by the growth temperature) relative to the growth flux. We further observe that the distribution of quantum dot heights, for samples grown under varying conditions, if normalized to the mean height, can be nearly collapsed onto a single Gaussian curve.
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
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.
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.
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.
Journal of Luminescence, 2012
We have investigated the optical properties of InAs/GaAs (1 1 3)A quantum dots grown by molecular beam epitaxy (MBE) with different growth rates by photoluminescence spectroscopy (PL) as a function of the excitation density and the sample temperature (10-300 K). Reflection high-energy electron diffraction (RHEED) is used to investigate the formation process of InAs quantum dots (QDs). A redshift of the InAs QDs PL band emission was observed when the growth rate was increased. This result was explained by the increase of the InAs quantum dot size with increasing growth rate. A significant redshift was observed when the arsenic flux was decreased. The evolution of the PL peak energy with increasing temperature has showed an S-shaped form due to the localization effects and is attributed to the efficient relaxation process of carriers in different InAs quantum dots and to the exciton transfer localized at the wetting layer.