Bound Exciton Complexes in CdSe Crystals

Cathodoluminescence and reflectivity spectra are studied in homogeneous CdS,Sel --2 mixed crystals with x = 0.85, 0.64, 0.47, 0.29 over the temperature range 7 to 110 K. It is found that the luminescence at 7 K is dominated by bound exciton emission. The binding energies of exciton complexes are deduced from the spectra and found to decrease linearly with the increase of selenium content in the crystals. It is concluded that excitons in different CdS,Sel-mixed crystals are bound to the same impurity or defect.Les spectres de cathodoluminescence e t de reflectivitk des cristaux melanges CdS,Sel -x pour x = 0,85; 0,64; 0,47; 0,29 sont etb etudib dans la gamme 7 it 110 K de la temperature. On a trouve que les excitons lies jouent un r61e dominant dans les spectres de luminescence S 7 K. En tenant compte de les spectres on a dedui I'energie de liaison de complexes d'excitons e t on a trouvb depreciation linearement de l'energie de liaison avec la croissance de contenu de sB18nium dans le cristal. On a conch que les excitons pour les differentes cristaux melanges CdS,Sel-, sont liB avec m&me I'impurities ou les mCme dkfauts. 1) 05-4006wierk, Poland. 2)

“…Pig. 3 presents the exciton binding energy as a function of composition together with the binding energies of I, and I, complexes in CdS [13] and CdSe [14].…”

Section: Discussionmentioning

confidence: 99%

A Study of Excitonic Spectra in CdS_xSe_1−x Mixed Crystals

Kozanecki¹,

Werner²,

Rzewuski³

et al. 1978

“…This will result in the shift of calculated LIC as given by (12) to higher values of I,,, with increasing T because of the temperature-induced change of I , according to (10).…”

Section: (12)mentioning

confidence: 98%

“…The dependence of y on T also can be explained by the proposed model if one makes the natural assumption that the surface recombination rate s becomes larger at higher temperatures. This will result in the shift of calculated LIC as given by (12) to higher values of I,,, with increasing T because of the temperature-induced change of I , according to (10).…”

Section: Theorymentioning

confidence: 99%

Nonlinearities in Excitonic Luminescence of Direct‐Gap Semiconductors under Very Low Optical Excitation Levels

Brodin

Gushcha

Khotiaintsev

et al. 1987

increases gradually with the decrease of I,,, and also becomes higher with increasing of temperat'ure. Linearity ( y = 1) is sometimes observed only a t sufficiently high I,,, above 10l6 quanta x x s-l. A phenomenological theoretical model is proposed which accounts for non-radiative surface recombination and non-uniform spatial distribution of the excited carriers and provides satisfactory qualitative agreement with the experimental findings.

“…2. The energetic positions of the lines are calculated with respect to the 1, line and compared with literature values [15] in Table 1. Comparing the data in Table 1 with the estimated uncertainty of +_0.08 meV in the presented analysis, we have demonstrated the power of NQBS as a spectroscopic technique.…”

Section: The Upper Curve Inmentioning

confidence: 99%

Nonlinear Quantum Beats of Excitons in CdSe

Pantke

Schillak

Erland

et al. 1992

Self Cite

By observing quantum beats in the self-diffracted signal from a nonlinear mixing process in a crystal, and by spectrally resolving this signal, information is obtained about solid state parameters, such as energy splittings and energy shifts. This technique is used to study bound excitons in CdSe with a strong, resonant third-order susceptibility. Furthermore, in the region of free exciton propagation, effects on the third-order nonlinear polarization are observed and explained by quantum beats between propagating polaritons. ')