The effects of carrier thermal escape and retrapping on the temperature dependence photoluminescence InAs/GaAs self-assembled quantum dots are investigated. A systematic experimental study evolution spectra in two different sets samples is reported. behavior well reproduced terms a steady state model for dynamics which takes into account quantum-dot size distribution, random population effects, capture, relaxation, retrapping. relative contributions these processes to quenching discussed.

We investigated the temperature dependence (10–180 K) of photoluminescence (PL) emission spectrum self-organized InAs/GaAs quantum dots grown under different conditions. The PL intensity is determined by two thermally activated processes: (i) quenching due to escape carriers from and (ii) carrier transfer between via wetting layer states. existence dot families confirmed deconvolution spectra in gaussian components with full width half maxima 20–30 meV. excitation responsible for sigmoidal...

We present a complete study both by experiments and model calculations of quantum dot strain engineering, which few optical properties nanostructures can be tailored using the dots as parameter. This approach used to redshift beyond 1.31μm and, possibly, towards 1.55μm room-temperature light emission InAs embedded in InGaAs confining layers grown on GaAs substrates. show that controlling simultaneously lower layer thickness layers’ composition, energy gap material band discontinuities...

We prepared by molecular-beam epitaxy and studied structures of InAs quantum dots embedded in InxGa1−xAs confining layers. The were designed so that the strain could be controlled independently In composition such a way, we single out effect on energy photoluminescence emission. show can effectively used to tune emission dots, room-temperature at 1.3 μm obtained. Our results suggest quantum-dot engineering, it will possible extend wavelength beyond 1.55 μm.

We report on the growth by molecular beam epitaxy and study atomic force microscopy photoluminescence of low density metamorphic InAs/InGaAs quantum dots. subcritical InAs coverages allow to obtain 108 cm−2 dot InxGa1−xAs (x=0.15,0.30) confining layers result in emission wavelengths at 1.3 μm. discuss optimal parameters demonstrate single up 1350 nm temperatures, distinguishing main exciton complexes these nanostructures. Reported results indicate that dots could be valuable candidates as...

Multilayer structures of InAs quantum dots have been studied by means photoluminescence techniques. A strong increase the radiative lifetime with increasing number stacked dot layers has observed at low temperatures. Moreover, a temperature dependence lifetime, which is not present in single layer samples, found multistacked structures. The effects are nicely explained as consequence electronic coupling between electrons and holes induced vertical ordering.

We present design, preparation by molecular beam epitaxy, and characterization photoluminescence of long-wavelength emitting, strain-engineered quantum dot nanostructures grown on GaAs, with InGaAs confining layers additional InAlAs barriers embedding InAs dots. Quantum strain induced metamorphic lower is instrumental to redshift the emission, while a-few-nanometer thick allow significantly increase activation energy carriers’ thermal escape. This approach results in room temperature...

Photoluminescence (PL) and resonant PL (RPL) have been performed at low temperatures in a number of InAs/GaAs quantum dots (QD's) whose emission energies range from 1.4 to 1.08 eV. A simple, standard electron-phonon interaction model reproduces RPL spectra well. The value the $S$ is large for small QD's evolves values large, well-formed QD's. This trend consistent with recent experimental results InAs provides an basis theoretical speculations.

We designed and prepared by molecular beam epitaxy strain-engineered InAs∕InGaAs∕GaAs quantum dot (QD) nanostructures where we separately controlled: (i) the mismatch f between QDs confining layers (CLs), and, then, QD strain, changing thickness of a partially relaxed InGaAs lower CL (ii) composition x. The appropriate values x to tune emission energies at wavelengths in 1.3–1.55μm range were calculated means simple model. Comparing model calculations activation photoluminescence quenching,...

We report a detailed study of InAs∕GaAs quantum dot (QD) structures grown by molecular beam epitaxy with InAs coverages θ continuously graded from 1.5 to 2.9 ML. The effect coverage on the properties QD was investigated combining atomic force microscopy, transmission electron x-ray diffraction, photoluminescence, capacitance-voltage, and deep level transient spectroscopy. In 1.5–2.9 ML range small-sized coherent QDs are formed diameters densities that increase up 15nm 2×1011cm−2,...

We report on a photoluminescence and photoreflectance study of metamorphic InAs/InGaAs quantum dot strain-engineered structures with without additional InAlAs barriers intended to limit the carrier escape from embedded dots. From: (1) substantial correspondence activation energies for thermal quenching differences between wetting layer transition (2) unique capability assessing confined nature states, we confidently identify states as final ones process dots, which is responsible quenching....

In this work, we present a study of InAs quantum dots deposited on InGaAs metamorphic buffers by molecular beam epitaxy. By comparing morphological, structural, and optical properties such nanostructures with those InAs/GaAs dot ones, were able to evidence characteristics that are typical InAs/InGaAs structures. The more relevant are: the cross-hatched surface overgrown dots, change in critical coverages for island nucleation ripening, new defects capping layers, redshift emission energy....

Abstract New optical fiber based spectroscopic tools open the possibility to develop more robust and efficient characterization experiments. Spectral filtering light reflection have been used produce compact versatile cavities sensors. Moreover, these technologies would be also suitable study N-photon correlations, where high collection efficiency frequency tunability is desirable. We demonstrated single photon emission of a quantum dot emitting at 1300 nm, using Fiber Bragg Grating for...

Self-assembled InAs quantum dots have been grown by molecular beam epitaxy in such a way as to obtain continuous variation of coverages across the wafer. Structured photoluminescence spectra are observed after excitation large number dots; deconvolution into Gaussian components yields narrow emission bands (full width at half-maximum 20–30 meV) separated energy an average spacing 30–40 meV. We ascribe individual low families with similar shapes and heights differing one monolayer, strongly...

We compare results obtained in several tens of samples grown by molecular-beam epitaxy under different growth conditions with a substantial amount data found the literature. By plotting photoluminescence (PL) peak energy ${(E}_{p})$ quantum dot (QD) bands as function nominal thickness deposited InAs (L) three regions are clearly evidenced ${(E}_{p},L)$ plane. Below so-called critical ${(L}_{c}),$ three-dimensional precursors QD's show smooth dependence their emission on L. Around ${L}_{c},$...

We present a detailed study of the carrier thermodynamics in $\mathrm{InAs}∕{\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ self-assembled quantum dots performed via an accurate determination dependence dot photoluminescence efficiency on temperature, excitation power density and wavelength. have found experimental evidences that electron hole populations are highly correlated. also show other puzzling effects, like onset superlinear integrated intensity density, stem from...

In this work we study the properties of energy levels two-dimensional quantum system composed by wetting layers and thin capping in low density InAs/InGaAs dot structures, that can be used as single photon sources at fiber-optic wavelength 1.3 μm. We show how, thanks to dots, x-ray characterization structures allows extract thicknesses compositions InAs layer well formed InGaAs layer, resulting substantial deviations from simplified picture a consisting 1.6 monolayer thick square well. The...

III-V semiconductor quantum dots are strong candidates for single photon sources and fundamental cornerstones in the growing field of cryptography computing. We present an original MBE growth approach, based on deposition sub-critical coverages InAs metamorphic InGaAs buffers, that allows us to obtain low surface densities QDs emitting 1.3–1.55 μm telecom spectral window. Thanks unique properties system, which independently change QD strain buffer composition, we discuss how regime is...

We study the growth by Molecular Beam Epitaxy of InAs quantum dots (QDs) on InGaAs metamorphic buffers (MBs), allowing independent control mismatch f between QDs and MBs (7.2% > 4.5%) In content x surface underlying (0 ≤ 0.35), taking advantage dependence MB strain relaxation thickness. AFM characterization indicated an enlargement QD diameters for ≥ 0.35, while changing had negligible effects. The two-dimensional (2D) to three-dimensional (3D) critical thickness θc was measured RHEED: fixed...

Strain engineering allows the physical properties of materials and devices to be widely tailored, as paradigmatically demonstrated by strained transistors semiconductor lasers employed in consumer electronics. For this reason, its potential impact on our society has been compared that chemical alloying. Although significant progress made last years nanomaterials, strain fields (which are tensorial nature, with six independent components) still mostly used a "scalar" and/or static fashion....

We present research carried out on molecular beam epitaxy grown InAs/(In)GaAs quantum dot structures for single-photon operation at long wavelengths. The optical and morphological properties of the are studied as functions growth parameters InGaAs upper confining layer thickness composition. show that low rate, high temperature reduced coverage very effective in reducing density but, owing to In desorption effects size reduction, this result is not always concomitant with achievement...