The exciton binding energy serves as a critical criterion for identification of the nature of elementary excitations (neutral excitons versus a pair of charged carriers) in semiconductor materials. An exciton binding energy of 0.41 eV is determined experimentally for a selected nanotube type, the (8,3) tube, confirming the excitonic nature of the elementary excitations. This determination is ma...

We have studied the quasi-two-dimensional exciton in ZnSe/ZnxMg12xSySe12y ~x50.85, y50.21! single quantum wells ~SQWs! by photoluminescence and photoluminescence excitation spectroscopy. Self-consistent calculations of the peak energies for a series of SQWs give the conduction band discontinuity DEc50.40DEg and the binding energy of the n51 heavy-hole exciton Eb~hh1!522.1 meV for an 8 nm well w...

Exciton binding energy and excited states in monolayers of tungsten diselenide (WSe(2)) are investigated using the combined linear absorption and two-photon photoluminescence excitation spectroscopy. The exciton binding energy is determined to be 0.37 eV, which is about an order of magnitude larger than that in III-V semiconductor quantum wells and renders the exciton excited states observable ...

The optical properties of monolayer transition metal dichalcogenides (TMDC) feature prominent excitonic natures. Here we report an experimental approach to measuring the exciton binding energy of monolayer WS₂ with linear differential transmission spectroscopy and two-photon photoluminescence excitation spectroscopy (TP-PLE). TP-PLE measurements show the exciton binding energy of 0.71 ± 0.01 eV...

The exciton binding energy (E(b)) and the band gap energy (E(g)) of poly(phenylene vinylene) are determined by high-resolution measurements of the photoconductivity excitation profile as a function of light polarization, applied electric field, and temperature. At high applied electric fields, a peak in the photoconductivity is observed when the sample is pumped at a photon energy just below th...

Hartree–Fock solutions of the Pariser–Parr–Pople and MNDO Hamiltonians are shown to give reasonable predictions for the ionization potentials and electron affinities of gas-phase polyenes. However, the energy predicted for formation of a free electron-hole pair on an isolated chain of polyacetylene is much larger than that seen in the solid state. The prediction is 6.2 eV if soliton formation i...

The scaling of exciton binding energy in semiconductor quantum wires is investigated theoretically through a non-variational, fully three-dimensional approach for a wide set of realistic state-of-the-art structures. We find that in the strong confinement limit the same potential-to-kinetic energy ratio holds for quite different wire cross-sections and compositions. As a consequence, a universal...

In the present work we report on the AlN gap energy temperature dependence studied through the optical properties of high-quality large bulk AlN single crystals grown by a sublimation–recondensation technique. The cathodoluminescence, transmission/absorption as well as optical reflectance measurements at low temperature show a clear feature at about 6.03 eV, which could be attributed to the fre...