Exciton

About: Exciton is a research topic. Over the lifetime, 31603 publications have been published within this topic receiving 810642 citations.

Ordered arrays of quantum dots: Formation, electronic spectra, relaxation phenomena, lasing

Abstract: Elastic relaxation on facet edges, renormalization of the surface energy of the facets, and interaction between i&no3 via the strained substrate are the driving forces for self-organization of ordered arrays of uniform coherent three-dimensional is/a& on crystal surfaces. For a (100) surface of a cubic crystal, two-dimensional square lattice of pyramid-like islands (quantum dots) with the periodicity along the directions of the lowest stiffness (OlO) and (OOI) has the minimum energy among different one-dimen- sional and two-dimensional arrays. For the InAs/GaAs(lOO) system, an equilibrium array of dots of the lateral size _ 120-140 A exists in a fixed range of growth parameters. T'he main luminescence peak at 1.1 eV, as well as peaks of excited states coincide in energy with the peaks revealed in the calorimetric absorption spectra regardless of the amount of InAs deposited (2-5 ML). Raman spectra indicate significant strain in InAs dots. The "phonon bottleneck" effect is bypassed via multi-phonon exciton and carrier relaxation. Ultranarrow lines (< 0.15 meV) are observed in cathodoluminescence spectra up to high temperatures. Low threshold current density operation via zero-dimensional states and ultrahigh temperature stability of the threshold current (T, = 450 K) are realized for a quantum dot injection laser. Increase in the gain and significant reduction in the radiative lifetime are possible via the self-organization of vertically-coupled quantum dots (VECODs) arranged in a well ordered artificial three-dimensional tefragonal lattice.

All‐Inorganic CsCu2I3 Single Crystal with High‐PLQY (≈15.7%) Intrinsic White‐Light Emission via Strongly Localized 1D Excitonic Recombination

Abstract: Energy-saving white lighting from the efficient intrinsic emission of semiconductors is considered as a next-generation lighting source. Currently, white-light emission can be composited with a blue light-emitting diode and yellow phosphor. However, this solution has an inevitable light loss, which makes the improvement of the energy utilization efficiency more difficult. To deal with this problem, intrinsic white-light emission (IWE) in a single solid material gives a possibility. Here, an all-inorganic lead-free CsCu2 I3 perovskite single crystal (SC) with stable and high photoluminescence quantum yield (≈15.7%) IWE through strongly localized 1D exciton recombination is synthesized. In the CsCu2 I3 , the Cu-I octahedron, which provides most of electron states, is isolated by Cs atoms in two directions to form a 1D electronic structure, resulting a high radiation recombination rate of excitons. With this electronic structure design, the CsCu2 I3 SCs have great potential in energy-saving white lighting.

Near‐band‐gap photoluminescence from pseudomorphic Si1−xGex single layers on silicon

Abstract: The systematic study of band‐edge luminescence in pseudomorphic Si/Si1−xGex/Si double‐heterostructure layers is reported for a wide composition range, 0.12

Optical manipulation of the exciton charge state in single-layer tungsten disulfide

Abstract: Raman scattering and photoluminescence (PL) emission are used to investigate a single layer of tungsten disulfide (WS${}_{2}$) obtained by exfoliating $n$-type bulk crystals. Direct gap emission with both neutral and charged exciton recombination is observed in the low temperature PL spectra. The ratio between the trion and exciton emission can be tuned simply by varying the excitation power. Moreover, the intensity of the trion emission can be independently tuned using additional subband gap laser excitation.

Controlled Synthesis of Ag2S Quantum Dots and Experimental Determination of the Exciton Bohr Radius

Abstract: Ag2S quantum dots (QDs) have attracted increasing attention due to their appealing optical properties in the near-infrared regime. However, a full understanding of the quantum confinement effect of Ag2S QDs has not been achieved so far. Herein, for the first time, the size-dependent excited state optical properties of Ag2S QDs are systematically investigated by photoluminescence (PL), PL excitation (PLE), and time-resolved PL spectroscopy. Experimentally, we determine the exciton Bohr radius of Ag2S QDs as 2.2 nm, which is highly consistent with theoretical results.