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Amorphous Cd-doped GeS2 films were prepared by thermal evaporation. In the Raman spectra of GeS2:Cd films with nominal Cd content above 8% at high laser power densities (above 200 kW/cm2), Raman peaks of the CdS LO and 2LO phonons are observed as evidence for the formation of CdS nanocrystals in the films under laser irradiation. The nanocrystals are formed due to the photoenhanced diffusion of atoms in the GeS2:Cd films, which is caused by non-thermal photofluidity (a drastic decrease of the film viscosity under illumination) that enables the aggregation of Cd and S atoms in nanocrystals. Factors responsible for the variation of the CdS LO phonon peak as a function of laser power density are discussed.

Basing on dilatometric and optical anisotropy studies, we have obtained (x, T)-phase diagram for TlIn(S1–xSex)2 solid solutions in the range 0 ≤ × ≤ 0.25 of selenium concentrations. It has been fou...

Features related to molecular dimers of selenium Se2 are observed in the Raman spectra of borosilicate glass doped with Se-rich II–VI nanocrystals as well as in the Raman spectra of decolored (ther...

Zn-doped As2Se3 and As2S3 films were prepared by thermal evaporation. Their amorphous structure was confirmed by Raman spectroscopy. Zinc chalcogenide nanocrystals can be formed in the films under laser irradiation due to the photoenhanced diffusion of atoms in the arsenic chalcogenide films, which enables aggregation of Zn and S(Se) atoms in nanocrystals. For As2S3:Zn films, not only ZnS, but also ZnO crystallites can be formed under irradiation with UV laser light due to oxidation of the film surface with abundant zinc atoms.

Temperature and pressure dependences of dielectric characteristics of TlIn(S1−xSex)2 polycrystals for 0 ≤x≤ 0.15 are studied. Their phase (x, T) and (p, T) diagrams are built. With increasing Se co...

Amorphous In-doped As2Se3 films with nominal indium contents x up to 7 at.% were prepared by thermal evaporation. Atomic force microscopy studies confirm the uniform film structure with a surface roughness near 5 nm, noticeably higher than for similarly prepared undoped As2Se3 film. X-ray photoelectron spectroscopy (XPS) studies enabled the chemical composition of the films to be examined. As follows from the XPS data, the In content in the film strongly decreases with the film depth. For films with x ≥ 2 at.%, Raman features attributed to transverse and longitudinal optical phonons of InAs are revealed in the Raman spectra as an evidence for the formation of InAs nanocrystallites in the As2Se3:In film under laser illumination.

Amorphous As2S3 films with surface roughness near 0.5 nm were prepared by thermal evaporation. Raman measurements performed under ultraviolet (UV) laser excitation (325 nm) revealed a series of sharp intense peaks appearing at laser power density Pexc above 150 kW/cm2. No such effects were observed at Raman measurements under visible (514.7 or 632.8 nm) light excitation, even for much higher Pexc values. The new Raman peaks are identified as arsenolite (As2O3) features. UV light-assisted oxidation of the As2S3 surface is discussed.

Raman spectra of TlIn(S 1– x Se x ) 2 (0 ≤ x ≤ 0.25) single crystals in the frequency range 16–400 cm −1 were studied at T = 30 K in the Z ( XX+XY ) Z ¯ configuration. The experimental Raman spectra of TlIn(S 1-x Se x ) 2 single crystals were analyzed by multi-peak simulation by Lorentzian contours, enabling the peak frequencies, halfwidths and intensities to be determined. Their compositional dependences were studied. Compositional behaviour of Raman features revealed in the spectral regions 40–85 cm −1 and 190–220 cm −1 is discussed in view of different number of isovalent S and Se atoms in structural groups corresponding to the general formula of In 4 S 10– y Se y .

Amorphous Cd-doped As 2 Se 3 films with nominal Cd contents up to 12 at.% were prepared by thermal evaporation. Atomic force microscopy studies confirm the uniform film structure with surface roughnesses below 1 nm, independent of the Cd content. As shown by energy-dispersive X-ray spectroscopy, the Cd content in the film reveals a strong gradient and decreases with the film depth. For heavily Cd-doped (above 7 at.%) As 2 Se 3 films, Raman features attributed to CdSe longitudinal optical (LO) phonon and its overtone (2LO) are revealed in the Raman spectra as an evidence for the formation of CdSe nanocrystallites in the As 2 Se 3 :Cd film under above-bandgap or below-bandgap laser illumination. The CdSe nanocrystallites undergo tensile strain due to a photoplastic effect in the As 2 Se 3 film, i. e. partial removal of the material from the laser spot. The tensile strain value, estimated from the LO phonon frequency shift, is shown to reach nearly 2 GPa.

Photoinduced deformation of an amorphous As2S3 film surface under illumination by sub-bandgap (638 nm) and above-bandgap (532 nm) polarized laser light at oblique incidence are studied by atomic force microscopy performed directly after the film exposure to the laser beam. Photoinduced expansion as well as directional mass transport from the laser spot are observed. The photodeformation character under sub-bandgap and above-bandgap illumination are discussed in view of the optical forces (gradient force and scattering force) due to the interaction of light with the amorphous As2S3 film .

Real and imaginary parts of the dielectric function of TlIn(S 1- x Se x ) 2 ( x = 0.05, 0.08, 0.25) single crystals were determined in the spectral range from 1 to 5 eV within a temperature interval 140–293 K from spectroscopic ellipsometry measurements. The energies of interband transitions (critical points) of the TlIn(S 1− x Se x ) 2 crystals were obtained from the second derivative of the real and imaginary parts of dielectric function. Structural phase transitions are behind the observed change of electronic band structure.

The paper by M. Xia et al. (Journal of Luminescence 186 (2017) 30–33) claims the formation of CdS/Cd1–xZnxS semiconductor quantum dots with a sandwiched (core/shell) structure in silicate glass by thermal treatment. We critically discuss their results and conclusions and compare them to other data available in literature, showing that by this technique only ternary nanocrystals can be formed in silicate glass and the data presented give no evidence for the formation of core/shell structures.

Yu.M. Azhniuk is grateful to Deutscher Akademischer Austauschdienst (DAAD) for the support of his research at Chemnitz University of Technology.

(As 2 S 3 ) 0.45 (SbSI) 0.55 thin films were studied by Raman spectroscopy and atomic force microscopy. Laser-induced crystallization of SbSI crystallites from the amorphous (As 2 S 3 ) 0.45 (SbSI) 0.55 thin films was observed in micro-Raman measurements as a result of local laser beam heating. The dependence of the observed effect on the laser power and the film pre-heating duration is discussed. No such effects were observed for bulk glasses with a similar composition.

Amorphous Zn-doped As2Se3 films with a nominal zinc content x up to 10 at.% were prepared by thermal evaporation. Their structure is characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoemission spectroscopy (XPS), and Raman spectroscopy. The AFM data show a considerable increase of the film surface roughness for films with x > 5 at.%. A strong gradient of the Zn content decreasing into the film depth is confirmed by the EDX and XPS data. Heavily Zn-doped (above 7 at.%) As2Se3 films reveal photostructural changes in the course of the Raman measurements. New Raman features are attributed to TO and LO vibrations of ZnSe nanocrystallites formed in the film under laser illumination. Depending on the laser wavelength and power density, the ZnSe nanocrystallites can experience tensile strain in the film due to a non-thermal photoplastic effect in the As2Se3 film resulting in a partial removal of the material from the laser spot. The tensile strain value, estimated from the TO and LO phonon frequency shift, is shown to reach up to 2.9 GPa.

The unpolarized Raman spectra of TlIn(S0.95Se0.05)2 single crystals in the frequency interval 16–340 cm−1 are studied in the temperature interval 30 ≤ T ≤ 293 K. The Raman spectra are analyzed by a multipeak simulation using Lorentzian contours. The temperature behavior of the vibrational band parameters (half-width, intensity, and frequency) is studied with the emphasis on the temperature range, where changes related to phase transformations are revealed.

Cd1−xZnxSe nanocrystals with x up to 0.28 and average diameter ranging from 6.5 to 12.5 nm were obtained in borosilicate glass by diffusion-limited growth. Their average size and chemical composition were determined from the optical absorption and Raman scattering spectra. Comparison of the absorption and photoluminescence spectra exhibits a slight decrease of the Stokes shift with increasing nanocrystal size.

Tl–In–As–Se glasses are obtained by co-melting of As2Se3 and TlInSe2. Laser-induced crystallization of TlInSe2 in the glass due to local laser beam heating is observed in the course of micro-Raman measurements. Dependence of the crystallization process on the laser power is studied. Simultaneously a photoplastic effect in the glass is observed leading to the mass transfer from the laser spot.

Real and imaginary parts of the dielectric function of TlInS2 single crystals in the spectral range from 1 to 5 eV were determined within a temperature range of 133–293 K from spectroscopic ellipsometry measurements. The energies of interband transitions (critical points) for TlInS2 were obtained from the second derivatives of the dielectric function. Temperature dependent features observed in the temperature range of the structural phase transition (190–220 K) and at lower temperatures are discussed. Дійсну та уявну частини діелектричної функції кристалу TlInS2 визначено в спектральному діапазоні від 1 до 5 еВ в інтервалі температур 133-293 К із спектроскопічних еліпсометричних досліджень. Енергії міжзонних переходів (критичних точок) отримано для TlInS2 з других похідних від діелектричних функцій. Обговорюються особливості в області структурних фазових переходів (190-220 К) та при нижчих температурах. Из спектроскопических эллипсометрических исследований определена действительная и мнимая части диэлектрической функции кристалла TlInS2 в спектральном диапазоне от 1 до 5 эВ в интервале температур 133–293 К. Энергии между зонных переходов (критических точек) получено для TlInS2 из вторых производных от диэлектрических функций. Обсуждаются особенности в области структурных фазовых превращений (190–220 К) и при меньших температурах.

Phone: þ380 312 643 772, Fax: þ380 312 643 650The effect of X-ray irradiation (up to 3200Gy) on thephotoluminescence (PL) of CdSe nanocrystals embedded inpolyacrylamide and borosilicate glass matrices is studied. Inboth cases no PL quenching is observed: for the polyacryla-mide-embedded CdSe nanocrystals the PL intensity remainsstable, while for the borosilicate glass-embedded nanocrystalsit increases somewhat. The obtained PL behavior correlateswell with the optical absorption data. This testifies to theradiation stability of the optical characteristics of CdSenanocrystals inpolyacrylamide andirradiation-induced chargetransfer between the nanocrystals and the borosilicate glass.

A series of samples with quaternary CdS1−x−ySexTey nanocrystals with cations of three types distributed over nanocrystal lattice sites were grown in a borosilicate glass matrix by the diffusion-limited growth technique. Their Raman spectra confirm the three-mode compositional behaviour of CdS1−x−ySexTey phonon spectra. The compositional dependence of the LO phonon frequencies is analysed experimentally for a series of samples containing nanocrystals with x≈y.

The effect of X-ray irradiation on the optical absorption spectra of CdSe 1− x Te x nanocrystals embedded in a borosilicate matrix is studied. The observed blue shift of the absorption edge and bleaching of the confinement-related features in the spectra are related to X-ray induced negative ionization of the nanocrystals with charge transfer across the nanocrystal/matrix interface. The radiation-induced changes are observed to recover after longer post-irradiation storage at room temperature.

Screening of active substances based on styryl and trimethine cyanine dyes was carried out to prepare tetrafluoroborate ion-selective electrodes. Correlations between the nature of the organic cation (pKa) and working pH ranges of the sensors were studied. New tetrafluoroborate-selective PVC membrane electrodes based on an active substance formed by the ion pair of 2-(n-ethylcarbazol-3)-ethenyl-1,3,3-trimethyl-3H-indolium and 2-[3-(5,6-dimethyl-3-nonyl1,3-benzothiazol-2(3H)-ylidene)propenyl]-5,6-dimethyl-3-nonyl-1,3-benzothiazolium with tetrafluoroborate ion were developed. The electrodes are non-sensitive to pH in the range of 2–8 and can be used for boron determination in acidic media of 6–7 mol L � 1 H2SO4. The developed sensor was successfully applied for the determination of B2O3 in CdS(Se) nanocrystal-doped glasses.

Self-implanted silicon, exposed to thermal processing at high pressures, is studied by microRaman scattering. Implantation-induced amorphization as well as high-temperature and high-pressure treatment-induced solid-phase epitaxial regrowth of the amorphized layer are observed. Based on Raman-based strain profiles, the existence of layers with tensile and compressive strain at the depths within the projected range of the implanted ions is revealed. A retarding effect of high pressure on the epitaxial recrystallization process is confirmed.

Variation of the chemical composition of ternary CdS 1 -x Se x nanocrystals grown in borosilicate glass depending on the thermal treatment is studied by resonant Raman spectroscopy. It is shown that only for the nanocrystals with roughly equal content of substitutive S and Se chalcogen atoms (0.4 < x < 0.6) the nanocrystal composition is independent of the thermal treatment parameters. In other cases an increase of the thermal treatment temperature (625-700°C) and duration (2-12 h) results in a considerable increase of the predominant chalcogen content in the nanocrystals.

Phonon spectra of CdSe1–xTex nanocrystals grown in a borosilicate glass matrix, are studied by Raman spectroscopy. The experimental data are compared to those obtained by other authors for bulk and nanoscale CdSe1–xTex. With the account of the factors specific for glass-embedded nanocrystals, Raman spectroscopy is shown to be a reliable and non-destructive method to evaluate the ternary nanocrystal composition. Raman measurements performed at different excitation wavelengths enabled the compositional dispersion of the nanocrystals to be estimated. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Raman scattering by surface phonons in CdS1–xSex nanocrystals grown in a borosilicate glass matrix, is studied. CdSe-like and CdS-like surface phonon frequencies are shown to increase with the relevant component content in the nanocrystal composition. No clear size dependence of the surface phonon frequencies has been observed. On the other hand, surface phonons in CdS1–xSex nanocrystals exhibit resonant dependence on the Raman excitation wavelength. It is emphasized that measurements of Raman scattering by surface phonons in CdS1–xSex nanocrystals give no reason to judge upon the nanocrystal shape. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

While studying the effect of thermal treatment at 625–700°C on the formation of borosilicate glass-embedded CdSe or CdSe1−xSx nanocrystals, pronounced bands at 323 and 646 cm−1 were observed in the Raman spectra. They are assigned to Se2 clusters on the base of their frequency positions, widths, intensities, and resonance behavior. The precipitation of Se2 molecular clusters in borosilicate glass is shown to occur when the heat treatment temperature and/or duration are beyond the range, most suitable for the formation of CdSe or CdSe-rich CdSe1−xSx nanocrystals.

Photoluminescence spectra of electron-irradiated CdS 1− x Se x single crystals (0⩽ x ⩽0.6) are studied. The changes of the photoluminescence band intensities in the visible spectral range versus the irradiation dose appear to be different for the sulphur-rich and selenium-rich mixed crystals. The models for the corresponding recombination centres are discussed. High-energy irradiation is shown to result in the formation of isolated defects, not their clusters in CdS 1− x Se x .

Based on optical absorption and photoluminescence studies of CdS 1− x Se x nanocrystals embedded in borosilicate glass matrix under X-ray and electron irradiation a conclusion is made on the radiation-induced ionization of the nanocrystals. Alternative mechanisms which could explain the observed smearing and vanishing of confinement-related maxima in the absorption spectra and the absorption edge blue shift, are shown to be insignificant.

Optical absorption spectra of x-ray irradiated CdS1−xSex nanocrystals embedded in a borosilicate glass matrix are studied. The observed transformation of the confinement-related features in the spectra is related to the x-ray-induced negative ionization of the nanocrystals with charge transfer across the nanocrystal/matrix interface. The radiation-induced changes and their relaxation upon postirradiation storage as a function of nanocrystal size and composition are discussed.

Presentation des spectres a 80 et 300 K pour des cristaux soumis a un faisceau electronique de 7,3 MeV, la fluence variant entre 3•10 15 et 3•10 18 cm −2