Self-organized InP islands on (100) GaAs by metalorganic vapor phase epitaxy

The effect of growth temperature, deposition rate, and substrate misorientation angle on size, density, and uniformity of InP islands grown on (100) GaAs by metalorganic vapor phase epitaxy is investigated. The density of InP islands is observed to remain constant as a function of growth temperature in the temperature range of 620–680 °C. Below 620 °C the island density increases with decreasing temperature. Above 605 °C a subset of islands having a uniform size is observed. The degree of uniformity depends largely on the deposition rate and the size of the uniform islands on the growth temperature.Peer reviewe

Cascaded exciton emission of an individual strain-induced quantum dot

Single strain-induced quantum dots are isolated for optical experiments by selective removal of the inducing InP islands from the sample surface. Unpolarized emission of single, bi- and triexciton transitions are identified by power-dependent photoluminescence spectroscopy. Employing time-resolved experiments performed at different excitation powers we find a pronounced shift of the rise and decay times of these different transitions as expected from cascaded emission. Good agreement is found for a rate equation model for a three step cascade

Interference effects in photoreflectance of epitaxial layers grown on semi-insulating substrates

Interferences were observed in the photoreflectance spectra of homoepitaxial layers grown on semi‐insulating GaAs and InP substrates. The modulation mechanism responsible for the interference effect was studied from the frequency and temperature dependence of the interference amplitude and the effect of continuous wave illumination. The results are in agreement with the model that the modulation is due to electrons drifting to the interface from the surface. A simple model was used to fit the interference spectra to the Lorentzian wave forms from the substrate and the epitaxial layer.Peer reviewe

Catalyst-free growth of In(As)P nanowires on silicon

The catalyst-free metal organic vapor phase epitaxialgrowth of In(As)P nanowires on silicon substrates is investigated using in situ deposited In droplets as seeds for nanowiregrowth. The thin substrate native oxide is found to play a crucial role in the nanowire formation. The structure of the nanowires is characterized by photoluminescence and electron microscopy measurements. The crystal structure of the InPnanowires is wurtzite with its c axis perpendicular to the nanowire axis. Adding arsenic precursor to the gas phase during growth results in a bimodal photoluminescence spectrum exhibiting peak at the InAsP and InP band gap energies.Peer reviewe

Enhanced luminescence from catalyst-free grown InP nanowires

The surface effects in the optical properties of catalyst-free grownInPnanowires are investigated. Both as-grown nanowires and nanowires treated with hydrofluoric acid are studied using low- and room-temperature continuous-wave and time-resolved photoluminescence measurements and transmission electron microscopy. It is shown that the room-temperature photoluminescence intensity is increased by two orders of magnitude after the surface treatment, and that there is also a significant increase in the double-exponential photoluminescence decay time.Peer reviewe

Tensile-strained GaAsN quantum dots on InP

Self-assembled quantum dots are typically fabricated from compressive-strained material systems, e.g., InAs on GaAs. In this letter, self-assembled quantum dots from tensile-strained GaAsN on InP are demonstrated. GaAsN on InP has type-I band alignment. Stranski-Krastanov growth mode is not observed, but in situannealing of the uncapped samples results in the formation of islands. Photoluminescence spectra from the buried GaAsN show separate peaks due to a wetting layer and islands around the energies of 1.3 and 1.1eV, respectively.Peer reviewe

Selective growth of InGaAs on nanoscale InP islands

The formation of an InGaAs quantum well on nanoscale InP islands by selective growth using metalorganic vapor phase epitaxy is demonstrated. The structures show intense low‐temperature photoluminescence at 1.35 eV. The blueshift of the emission peak by increasing the excitation intensity suggests that the carriers are three‐dimensionally confined. The insertion of quantum well into the islands allows a better control of the properties of structuresfabricated by the self‐organizing growth, a novel technique to realize nanoscale structures without using any lithographical process steps.Peer reviewe

Carrier relaxation dynamics in quantum dots: Scattering mechanisms and state-filling effects

Stressor-induced InxGa1−xAs quantum dot structures of high structural quality allow a detailed experimental investigation of carrier relaxation between distinct zero-dimensional quantized states. Time-resolved photoluminescence studies combined with appropriate model calculations show that state filling effects, Coulomb scattering, and acoustic phonon scattering determine the relaxation scenario in a way characteristic for a zero-dimensional electronic system. These investigations allow a quantitative estimation of the inter-dot-level relaxation rates mediated by (i) Coulomb scattering and (ii) acoustic phonon scattering.Peer reviewe