Incorporation of zinc into CdS1?xSex nanocrystals in glass matrix studied by optical spectroscopies

Abstract

The formation of quaternary Cd1−yZnyS1−xSex nanocrystals in a borosilicate glass matrix due to incorporation of zinc into CdS1−xSex quantum dots under heat treatment is investigated by Raman scattering and optical absorption spectroscopy. Average size and composition of the nanocrystals are determined. Factors affecting the accuracy of Raman scattering‐based determination of the mixed nanocrystal composition are analyzed. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Phonon spectra of quaternary Cd1–yZny S1–xSex semiconductor nanocrystals grown in a glass matrix

“…For Cd 1-y Zn y Se the compositional transformation of the phonon spectrum is also reported as one-mode [17][18][19] or "mixed", with a rather weak band, intermediate in frequency [20][21][22]. In any case, for relatively small y, in both cases (Cd 1-y Zn y S and Cd 1-y Zn y Se), the compositional shift of the LO phonon frequencies is monotonous, the zinc-induced increment being given by Similarly to [13], the Se content for the NC series was determined from the LO phonon peak frequency difference Δν for the sample subjected to the least intense heat treatment. As follows from [23], for CdS 1-x Se x NCs x = 0.0165Δν -0.94 (Δν being taken in cm -1 ).…”

“…With the increase of the heat treatment temperature and duration the observed LO phonon frequencies increase as well as those of the two-phonon bands. Like in our earlier paper [13] where only one series of samples was studied, this is explained by partial Cd→Zn substitution and formation of quaternary Cd 1-y Zn y S 1-x Se x NCs due to the diffusion of Zn atoms from the matrix. Similarly, thermal diffusion of Zn to CdS NCs and formation of Cd 1-y Zn y S NCs was reported [5,14,15].…”

“…For ternary II-VI NCs which have been extensively studied by vibrational spectroscopy with an emphasize on nanometer-size-related effects (phonon confinement, marked contribution of surface phonons due to the high surface-tovolume ratio, size dispersion of NCs within the ensemble) [3][4][5][6][7][8][9][10][11][12]. With regard to quaternary II-VI NCs, their studies are extremely scarce [13]. The present work is aimed at obtaining Cd 1-y Zn y S 1-x Se x NCs in a borosilicate glass matrix and their characterization by Raman spectroscopy.…”

“…2 Experimental Cd 1-y Zn y S 1-x Se x NCs were grown in a borosilicate glass by solid-state precipitation technique, similar to the one described in [13]. After decolouring initial CdS 1-x Se x NC-doped alkali zinc borosilicate glass by annealing for 2 h at 1000 °C, the samples were subjected to heat treatment at T a ranging from 625 to 700 °C for 2 up to 12 h. The average size of the NCs was estimated from optical absorption spectra, measured using a LOMO MDR-23 spectrometer.…”

Thermal treatment-dependent chemical composition of ternary CdS1−xSex nanocrystals grown in borosilicate glass

“…In zinc-containing matrices an increase in the thermal treatment temperature or duration definitely results in the increase of Zn content in the ternary Cd 1 À x Zn x S [6,12] or quaternary Cd 1 À y Zn y S 1 À x Se x [26] nanocrystals obtained. Meanwhile, for chalcogen content in CdS 1 À x Se x nanocrystals a different behaviour with thermal treatment is reported.…”