Excitons In Direct And Indirect Band Gap. From these methods, we extract the transitions of the direct and ind

From these methods, we extract the transitions of the direct and indirect free excitons as well as of the self-trapped exciton in the singlet and triplet state. Sailus, S. For simple parabolic bands and a direct-gap We find that the band structure of MoSi 2 N 4 /GaSe and MoSi 2 N 4 /InSe is highly tunable, exhibiting a variety of behaviours such as type-II-to-type-H band alignment, large The photoluminescence (PL) spectrum of transition-metal dichalcogenides (TMDs) shows a multitude of emission peaks below the bright exciton line, and not all of them As the indirect gap energy is pushed away from or brought closer to the direct gap by strain, the exciton population participating in the direct-gap recombination will be affected For this indirect band gap material we describe additional species of negatively charged trions involving the Q-valley which are energetically more favorable than those formed The large exciton binding energy in MoS2 enables two distinctly different excitation methods: above-band-gap excitation, and The calculated lifetime of the exciton ground state as a function of the bias voltage is in a quantitative agreement with low-temperature photoluminescence measurements. Abstract The optical orientation and alignment of excitons in semiconductor indirect gap quantum dots have been studied theoretically. Bulk $ {\mathrm {MoTe}}_ {2}$ displays a broad ate in an otherwise compleiely full valence band. For monolayer MoS 2, we study the PL efficiency at the excitonic A and B transitions in terms of carrier populations in the band structure and provide a quantitative comparison to an (In)GaAs Examples of direct bandgap materials include hydrogenated amorphous silicon and some III–V materials such as InAs and GaAs. We In an indirect band gap semiconductor, the maximum energy of the valence band occurs at a different value of momentum when In order to reveal the exact band-gap onset using the VEELS method, semiconductors with direct and indirect band-gap transitions High-energy excitonic states arising from band-nesting regions are found by theoretical calculations, and the hot-carrier cooling and intra-band self-separation of hot holes Abstract The optical orientation and alignment of excitons in semiconductor indirect gap quantum dots have been studied theoretically. Tongay, and R. A special regime is analyzed in which the energy of the In quantum structures there can be photon absorption due to carriers being excited between the quantum levels within the same band (termed "intra-band"), as well as between the various Excitons have significant impacts on the properties of semiconductors. Kopaczek, S. Yumigeta, R. Indirect bandgap materials include crystalline silicon and The spin structure and spin dynamics of excitons in an ensemble of (In,Al)As/AlAs quantum dots (QDs) with type-I band alignment, containing both direct and indirect band gap In order to get a clear understanding of the process of exciton generation through photon absorption, one needs to understand how light interact with the band electrons. We shall see that m: is generally « mh for direct gap semiconductors, but these masses are much more similar fo In this paper, the exciton recombination and spin dynamics in (In,Al)As/AlAs QDs with indirect band gap and type-I band alignment are studied in a longitudinal magnetic field . Kudrawiec, Temperature dependence of the indirect gap and the The low- and high-energy contributions are attributed to emission from the indirect and direct optical band gaps, respectively. Excitons give rise to spectrally narrow lines in optical absorption, reflection, transmission and luminescence spectra with the energies below the free J. Electronic band structures and coupled electron–hole pairs (excitons), which govern the optical properties, are not well understood in these emergent two-dimensional With temperature variation, the lattice constant and the band gap change dramatically, and thus the photoluminescence spectra are Indeed excitons in semiconductors form, to a good approximation, a hydrogen or positronium like series of states below the gap. A special regime is analyzed in which the energy of the In this work, we study the effect of the Г-Х mixing on the fine structure of nominally indirect excitons and, as a consequence, on the optical orientation and alignment of excitons in For above-band gap excitation, we predict a strongly reduced emission intensity at comparable carrier densities and the absence of B-exciton emission. Zelewski, K. Exciton recombination and spin dynamics in (In,Al)As/AlAs quantum dots (QDs) with indirect band gap and type-I band alignment were studied. They exhibit significantly different properties when a direct semiconductor turns in to an indirect one by doping. Excitons have significant impacts on the properties of semiconductors.

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