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In this work, we present results on the synthesis and characterization of InP and InP@ZnS quantum dots (QDs), grown using a single-step chemical synthesis method without injection of hot precursors, varying the concentration of indium myristate in both cases. It was found a color variation of the QDs in solution due to the quantum confinement effects when the nanoparticle sizes are smaller than the exciton Bohr radius. The band-gap energy of the samples was determined from the absorption spectra. From the photoluminescence (PL) spectra, emission peaks located in the range from 2.1 to 3.0 eV were observed. Furthermore, an enhanced PL emission due to a passivation effect in the ZnS-covered InP QDs was obtained. From X-ray diffraction (XRD), it was shown the presence of crystalline phases of the InP, ZnS, and In2O3 nanoparticles, with sizes ranging from 8 to 10 nm as determined by high resolution transmission electron microscopy (HR-TEM). From X-ray photoelectron spectroscopy (XPS) analysis, it was confirmed the formation of InP, ZnS, and In2O3; moreover, by means of a valence band analysis, the electronic structure of the samples was further investigated. The effect of the indium myristate precursor concentration on the optical, structural, surface chemical, and electronic properties of InP and InP@ZnS QDs will be discussed. [ABSTRACT FROM AUTHOR]

A set of GaxIn1-xAsySb1-y quaternary layers were grown on (100) GaSb substrates using the liquid phase epitaxy technique (LPE). These layers were doped with tellurium and were characterized by Raman, Photoluminescence (PL) spectroscopy, and Secondary Ion Mass Spectroscopy (SIMS). Several optical modes were identified by performing Raman spectroscopy characterization at room temperature and observing the effect of the impurity concentration on the Raman mode frequencies. From secondary ion mass spectrometry the concentrations of Te in the liquid solutions and the electron densities present in the layers were obtained. Finally, these last results were compared with those obtained from low temperature photoluminescence spectroscopy measurements at low temperatures on this set of samples. [ABSTRACT FROM AUTHOR]

Abstract: CdS nanoparticles were synthesized by precipitation in aqueous solution using starch as the capping molecule, and the effect of the pH of the solution on the optical absorption, photoluminescence, and size of the nanoparticles was studied. Absorption spectra, obtained by photoacoustic spectroscopy, indicated that the band gap energy of the crystalline nanoparticles decreased from 2.68eV down to 2.48eV by increasing the pH of the solution from 9 up to 14. The X-ray diffraction analysis revealed that the CdS nanoparticles were of zinc blende structure, and that the particle size increased from 1.35nm up to 2.45nm with increasing pH. In addition, temperature-dependent photoluminescence (PL) measurements of the capped material showed a blue-shift of the emission peak for temperatures higher than 150K, indicating the influence of starch on the formation of defect levels on the surface of the CdS nanoparticles. [Copyright &y& Elsevier]

Abstract: By means of the sol–gel growth technique undoped (CdO)1−x –(InO3/2) x thin films were prepared in the entire 0≤x≤1 range. The values of x studied were 0.0, 0.16, 0.33, 0.50, 0.67, 0.84 and 1. X-ray diffraction measurements showed that the films were mainly composed of CdO, In2O3, and CdIn2O4. CdO and In2O3 were obtained for x=0 and 1, respectively, and for x=0.67, which is the stoichiometric composition of the CdIn2O4 compound, only this oxide was formed. CdO and CdIn2O4 crystals were obtained in the Cd-rich region, whereas In2O3 and CdIn2O4 crystals were formed in the In-rich region. X-ray diffraction, atomic force microscopy, UV–vis spectroscopy and photoluminescence (PL) measurements were carried out at room temperature for the material characterization. At x=0, i.e. for CdO, PL showed the presence of three main emission bands centered at energies 2.0, and 2.3 and 2.9eV. Even with the fact that films do not form a continuous solid solution of CdO and In2O3 in all the 0≤x≤1 range studied, the material seems to have a graded evolution of these three bands observed in CdO as x moves from 0 to 1, that is from CdO to In2O3. The band at 2.0eV has a red shift when x increases; on the contrary, a blue-shift of the bands at 2.3 and 2.9eV takes place for increasing In concentration, which is related to the increase in the band-gap energy of the mixed system. Actually, this work is a continuation of a previous report of PL at low temperatures. [Copyright &y& Elsevier]

• InP-In 2 O 3 QDs are synthesized by a single-step chemical method without injection of hot precursors. • HR-TEM images show the synthesis of InP and In 2 O 3 QDs. • The InP and In 2 O 3 QDs size increases with the P(TMS) 3 concentration. • PL spectra reveal emission bands attributed to InP and In 2 O 3 QDs. • XPS confirms the formation of InP, In 2 O 3 and amorphous InPO x. InP-In 2 O 3 colloidal quantum dots (QDs) synthesized by a single-step chemical method without injection of hot precursors (one-pot) were investigated. Specifically, the effect of the tris(trimethylsilyl)phosphine, P(TMS) 3 , precursor concentration on the QDs properties was studied to effectively control the size and shape of the samples with a minimum size dispersion. The effect of the P(TMS) 3 precursor concentration on the optical, structural, chemical surface, and electronic properties of InP-In 2 O 3 QDs is discussed. The absorption spectra of InP-In 2 O 3 colloids, obtained by both UV–Vis spectrophotometry and photoacoustic spectroscopy, showed a red-shift in the high-energy regime as the concentration of the P(TMS) 3 increased. In addition, these results were used to determine the band-gap energy of the InP-In 2 O 3 nanoparticles, which changed between 2.0 and 2.9 eV. This was confirmed by Photoluminescence spectroscopy, where a broad-band emission displayed from 2.0 to 2.9 eV is associated with the excitonic transition of the InP and In 2 O 3 QDs. In 2 O 3 and InP QDs with diameters ranging approximately from 8 to 10 nm and 6 to 9 nm were respectively found by HR-TEM. The formation of the InP and In 2 O 3 phases was confirmed by X-ray Photoelectron Spectroscopy. [ABSTRACT FROM AUTHOR]