Phase transformation on CdSe thin films under annealing in Ar+Se 2 atmosphere

Portillo-Moreno, O.; Lozada‐Morales, R.; Rubín‐Falfán, M.; Pérez‐Álvarez, J.; Zelaya-Ángel, O.; Baños‐López, L.

doi:10.1016/s0022-3697(00)00051-2

Cited by 29 publications

(22 citation statements)

References 20 publications

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“…It is known that the stable structure of CdSe is hexagonal wurzite, but CdSe prepared by CBD usually has the cubic zincblende structure. According to Portillo-Moreno et al, the phase transformation to the hexagonal structure occurs around 355 C [11], and this is consistent with the present result that the 300 C annealed film is still in the zincblende structure. The average crystal size (particle diameter) obtained from the Debye-Scherrer formula is in a range 17-22 nm for the 300 C annealed films.…”

Section: Chemical Reactions and Experimental Proceduressupporting

confidence: 93%

Properties of Photochemically Deposited CdSe Films

Ichimura

Sato

Nakamura

et al. 2002

phys. stat. sol. (a)

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Section: Chemical Reactions and Experimental Proceduressupporting

confidence: 93%

Properties of Photochemically Deposited CdSe Films

Ichimura

Sato

Nakamura

et al. 2002

phys. stat. sol. (a)

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“…The peak around 680 nm is obtained for all the stoichiometric samples with only a variation of its intensity while the broad emission band at high wavelength is characteristic of the samples with an excess of Se. For the stoichiometric NWs, the peak position and the narrow shape are coherent with the experimental and calculated bandgap of cubic CdSe films slightly superior to the bandgap of hexagonal CdSe [31][32][33] and the PL band could be assigned to excitonic emission. Let us remark that due to the large NW diameters (around 100 nm), no confinement effect can occur.…”

Section: Resultssupporting

confidence: 75%

Temperature and pH influences on the structural and the emission properties of electrodeposited CdSe nanowires

Mallet

Kante

Fricoteaux³

et al. 2011

J Solid State Electrochem

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Cadmium selenite (CdSe) nanowires have been electrodeposited by potentiostatic method using polycarbonate membranes as template. For the same potential value, the pH modification of the solution or the temperature variation of the substrate leads to drastic differences of the CdSe composition. A meticulous study of the influence of both temperature and pH value on the stoichiometry of electrodeposited CdSe nanowires has been done and several combinations of temperature/pH leading to the 50-50 CdSe composition have been found. The as-electrodeposited CdSe nanowires under these specific conditions reveal a good crystallinity with a <111> preferred growth orientation exhibiting a luminescence band in the visible range corresponding to the CdSe gap.

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“…Cadmium selenide is characterized by rich and complex crystalline chemistry as well [33,34]. At conditions close to the ambiental ones, it exists in two polymorph modifications: cubic (sphalerite structural type) and hexagonal (wurtzite structural type).…”

Section: Introductionmentioning

confidence: 99%

Sonochemically assisted colloidal route to CdSe quantum dot assemblies: an alternative way to further fine-tune the size-dependent properties

Pejova

Bineva

2016

J Mater Sci: Mater Electron

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Continuous-wave heterogeneous sonochemical method was developed to synthesize 3D assemblies composed by QDs of metastable (cubic) modification of CdSe with sphalerite structural type. 3D QD assemblies were deposited in thin film form and as bulk precipitates. Structure, surface morphology, optical absorption as well as charge carriers' and phonon confinement effects were studied in details. The average nanocrystal radius, calculated by the Scherrer and Williamson-Hall methods, diminishes from 2.7 nm for samples synthesized by conventional colloidal chemical route to 2.0 nm for samples synthesized by sonochemical route. Upon post-deposition thermal annealing this value increases to 12.0 nm. QD size decrease is followed by increase of the uni-directional lattice strain and dislocation density (as defined by Hirsch), as well as by decrease of the lattice constant value. Previous findings were justified by analysis of X-ray diffraction peaks shape, which were found to be dominated by the particle size-distribution, instead of non-uniform strain. The energy of the fundamental direct C v 8 ! C c 6 interband electronic transition, computed from optical absorption data within parabolic approximation for the dispersion relation, shifts from 2.67 eV for sonochemically deposited samples and 2.08 eV for chemically deposited ones, to 1.77 eV upon post-deposition thermal treatment (close to the bulk value of 1.74 eV). The type of ''interband'' transitions does not change upon dimensionality reduce. Enhanced band gap energy blue shift upon average QD size decrease is followed by oscillator strength increase. Such trends were rationalized in terms of 3D confinement effects on charge carriers' motion. Experimentally observed band gap energies agree very well with the predictions of the effective mass model of Brus. The next direct interband electronic transition, from the spin-orbit split component of the valence band to the conduction band, has been detected and analyzed. The 1LO bands in the Raman spectra of chemically and sonochemically deposited samples appear at 206 and 204 cm -1 , as compared to the bulk value of 210 cm -1 . The extent of homogeneous broadening of the corresponding band is larger in sonochemically deposited samples, indicating enhanced frequency of phonon-phonon collisions in smaller QDs. The observed frequency shifts are dominated by phonon-dispersion terms, instead of lattice contraction.

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Phase transformation on CdSe thin films under annealing in Ar+Se 2 atmosphere

Cited by 29 publications

References 20 publications

Properties of Photochemically Deposited CdSe Films

Properties of Photochemically Deposited CdSe Films

Temperature and pH influences on the structural and the emission properties of electrodeposited CdSe nanowires

Sonochemically assisted colloidal route to CdSe quantum dot assemblies: an alternative way to further fine-tune the size-dependent properties

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