Exciton confinement and trapping dynamics in double-graded-bandgap quantum nanowires

Abstract

We fabricate and study quantum dot structures incorporating quasi-one-dimensional excited states. The structures are realized by graded bandgap GaAs/AlGaAs quantum wires self-formed inside inverted tetrahedral pyramids. The ground state transitions exhibit typical characteristics of fully confined excitons, including single photon emission. Efficient carrier thermalization and relaxation, as well as correlated photon emission is observed also among the excited states, indicating the formation of quasi-one-dimensional multi-exciton states. These structures offer interesting possibilities for collecting and directing charge carriers towards heterostructured potential traps.

Photophysical Aspects of Varying Zn2+/ PbSe Nanostructures Mediated by RNA Leading to the Formation of Honeycomb-like Novel Porous Morphology

“…It is likely to have arisen because of the production of multiexciton per single photon upon excitation of PbSe in ZnSP1 at higher energies (2.755 eV) greater than the bandgap energy (0.278 eV) as shown below in eq . This aspect has earlier been demonstrated in IV– VI semiconductors by a number of workers. − Moreover, multiple exciton generation with higher charge carrier densities may create higher-energy states, which might transfer energy to the adsorbed dye, NB having higher standard redox potential (−0.12), before they could annihilate (eq ). The excited NB then emits at higher energy (670 nm; 1.85 eV) than that of PbSe (806 nm; 1.53 eV). Zn 2 + / ( PbSe ) n → hv Zn 2 + / ( PbSe ) n ( e − − h + ) x Zn 2 + / false( PbSe false) italicn false( normale − − normalh + false) italicy + NB → Zn 2 + / false( PbSe false) italicn + NB* where n is the agglomeration number, x > 1, and y > x .…”

“…This aspect has earlier been demonstrated in IV− VI semiconductors by a number of workers. 24−26 Moreover, multiple exciton generation with higher charge carrier densities may create higher-energy states, 27 which might transfer energy to the adsorbed dye, NB having higher standard redox potential (−0.12), 28 before they could annihilate (eq ii). The excited NB then emits at higher energy (670 nm; 1.85 eV) than that of PbSe (806 nm; 1.53 eV).…”

Numerical study of valence band states evolution in AlxGa1-xAs [111] QDs systems

“…1A) (Zhu et al, 2006), QDs (Fig. 1B) (Zhu et al, 2007), tailored QDs (Lazarev, Rudra & Kapon, 2023;Szeszko et al, 2012;Zhu et al, 2006) (Fig. 1E), QDMs (Zhu et al, 2009) (Fig.…”