The interplay between structural properties and charge transfer in self-assembled quantum ring (QR) chains grown by molecular beam epitaxy on top of an InGaAs/GaAs quantum dot (QD) superlattice template is analyzed and characterized. The QDs and QRs are vertically stacked and laterally coupled as well as aligned within each layer due to the strain field distributions that governs the ordering. The strong interdot coupling influences the carrier transfer both along as well as between chains in the ring layer and dot template structures. A qualitative contrast between different dynamic models has been developed. By combining temperature and excitation intensity effects, the tuning of the photoluminescence gain for either the QR or the QD mode is attained. The information obtained here about relaxation parameters, energy scheme, interlayer and interdot coupling resulting in creation of 1D structures is very important for the usage of such specific QR–QD systems for applied purposes such as lasing, detection, and energy-harvesting technology of future solar panels.
Articles you may be interested inInGaAs/GaAsP strain balanced multi-quantum wires grown on misoriented GaAs substrates for high efficiency solar cells Appl. Phys. Lett. 105, 083124 (2014); 10.1063/1.4894424 Theoretical analysis of GaAs/AlGaAs quantum dots in quantum wire array for intermediate band solar cell Detailed studies of solar cell efficiency as a function of temperature were performed for quantum wire intermediate band solar cells grown on the (311)A plane. A remotely doped one-dimensional intermediate band made of self-assembled In 0.4 Ga 0.6 As quantum wires was compared to an undoped intermediate band and a reference p-i-n GaAs sample. These studies indicate that the efficiencies of these solar cells depend on the population of the one-dimensional band by equilibrium free carriers. A change in this population by free electrons under various temperatures affects absorption and carrier transport of non-equilibrium carriers generated by incident light. This results in different efficiencies for both the doped and undoped intermediate band solar cells in comparison with the reference GaAs p-i-n solar cell device. V C 2014 AIP Publishing LLC.
The optical analysis of multilayer structures formed from the topmost layer of InGaAs/GaAs quantum rings (QRs) grown on a vertically stacked and laterally aligned InGaAs/GaAs quantum dot (QD) superlattice has been performed to elucidate the nature of the contribution from each layer. These hybrid structures representing a coupled QR chain layer and the layers of self-assembled QD chains display strong optical anisotropy. Unusually strong oscillations are observed in the circularly polarized photoluminescence (PL) intensities under magnetic field for emissions in the spectral range of the QD structure and these oscillations occur simultaneously with weaker oscillations related to the Aharonov-Bohm interference that modulates the emissions from the QR top layer of the structure. The behavior seen in the magneto-PL spectrum is interpreted in terms of joint effects associated to strain, spatial, and magnetic field confinements on the valence band states forming the magnetoexciton ground state of this multilayered structure. The result can be ascribed to a magnetically induced dark exciton contribution where the heavy-hole (type II) state becomes localized outside, whereas light-hole (type I) as well as electron states remain inside the spatial confinement area of the QD.
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