Resonant secondary emission of localized excitons in CdSI−xSex mixed crystals

Dynamics of Excitons in CdS, CdSe, and CdS1−xSex

“…The low-energy exponential tail is attributed to the localized states, while the extended excitons do still have a square root dependence. The transition between the two regions is the mobility edge EMIE D in the formation of localized excitonic states [22,23], firstly predicted in [24]. Some investigations [25,26] indicate, that a small offset exists also in the conduction band in the sense that the conduction band in CdS is several tens of meV lower than in CdSe.…”

Luminescence spectra and kinetics of disordered solid solutions

“…͑44͒ ln͓R n (Ϫi st, )͔ in form of a Taylor series in and keeping terms up to 2 we transform the integral of Eq. ͑44͒ to a Gaussian.…”

“…Street 1 has supposed that the intrinsic luminescence band of ␣ϪSi:H can be understood with the assumption that among the tail states a special group of ''radiative'' localized states exists, which forms a relatively narrow band with the maximum at 1.6 eV. Cohen and Sturge 3 and Permogorov et al 2 have claimed when studying II-VI solid solutions that the upper border of the luminescence band corresponds to the exciton mobility edge in the disordered system.…”

“…͑i͒ The steady state intrinsic luminescence at a lowexcitation levels of many disordered systems [1][2][3][4][5][6][7][8][9][10][11][12][13] including II-VI solid solutions, [2][3][4][5][6][7][8][9][10][11][12] is supposed to arise from recombination of the excitons localized in the wells of a potential profile induced by the disorder. A common spectroscopic feature of such systems is a considerable redshift of the luminescence with respect to the maximum of exciton absorption ͓or with respect to the band-gap edge, as in the case of ␣ϪSi:H ͑Ref.…”

Broadening of the excitonic mobility edge in a macroscopically disordered CdSe/ZnSe short-period superlattice

“…If this is not the case, the states of the same energy might be localized in one ''macroscopic'' part of the crystal and delocalized in another, without any possibility to communicate with each other. In spite of these restrictions, many experimental results on the dynamics of localized excitons both in bulk alloy samples 2,4,[5][6][7] and in two-dimensional ͑2D͒ QW systems 3,8,[9][10][11] of different semiconductors have been successfully interpreted in terms of the effective mobility edge concept. Furthermore, to the best of our knowledge, no experimental measurements have been so far reported, directly suggesting that extended and localized excitonic states of comparable densities may coexist at the same energy within the same disordered semiconductor medium.…”