Amorphous Se/CdSe and SiO x /CdSe multilayers

Popescu, M.; Sava, F.; Lőrinczi, Á.; Vateva, E.; Nesheva, D.; Tchaushev, G.; Mihăilescu, I. N.; Koch, P.-J.; Obst, Stefan; Bradaczek, H.

doi:10.1117/12.312698

Cited by 2 publications

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“…The CdSe sublayer thickness in the multilayers here studied was varied between 2.5 and 10 nm as the thickness ratio of SiO x and CdSe sublayers was kept 1.3. The small-angle x-ray diffraction studies performed on the SiO x /CdSe multilayers [11] have revealed a good superlattice periodicity. The total thickness of all superlattices here studied was about 0.2 µm.…”

Section: Methodsmentioning

confidence: 99%

Experimental studies on the defect states at the interface between nanocrystalline CdSe and amorphous SiO_x

Nesheva

Levi

Aneva

et al. 2000

J. Phys.: Condens. Matter

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Superlattices of a-SiO x /nc-CdSe and thin composite films of SiO x doped with CdSe nanocrystals have been investigated. The CdSe nanocrystals size in both kinds of samples was determined by x-ray diffraction and HREM measurements. A significant difference has been found in the size values determined by both methods, which has been ascribed to appreciable nanocrystal lattice deformations. Subband absorption, room-temperature photoluminescence and thermally stimulated currents have been measured. It has been observed that in the superlattices the absorption in the tail region increases as sublayer thickness decreases. A new photoluminescence band has also appeared in the superlattices having thinnest (2.5 nm) CdSe sublayers. Two new maximums at about 220 K and 240 K, not existing in the CdSe single layers studied, have been found in thermally stimulated current spectra of the composite films. Both maximums are less expressed in the superlattices. The described results have been connected with a size-induced increase in the concentration of interface defect states in CdSe nanocrystals. It has been estimated that these defects are disposed at about 0.35 eV above the highest occupied molecular orbit in CdSe.

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Section: Methodsmentioning

confidence: 99%

Experimental studies on the defect states at the interface between nanocrystalline CdSe and amorphous SiO_x

Nesheva

Levi

Aneva

et al. 2000

J. Phys.: Condens. Matter

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“…Figs.1a and b show that at low substrate temperatures and a thickness ratio of d matrix =d CdSe ¼ 20 the surface roughness of the 'matrix' layers is sufficient to ensure the formation of quasi-isolated CdSe nanoparticles. However, multilayer structures fabricated as described above, but having a thickness ratio d matrix =d CdSe E1 (d ¼ 2210 nm) and a smooth surface of the 'matrix' layers behave as high quality amorphous/nanocrystalline multiple quantum wells [11,17,18]. These results prove the correctness of the suggested mechanism of selforganized nanocluster formation on a rough surface and indicate that the multilayer vapor deposition technique may be applied for fabrication of both II-VI nanoclusters in various matrices and multiple quantum well structures from various materials.…”

Section: Nanoparticle Formationmentioning

confidence: 99%

Nanoparticle layers of CdSe buried in oxide and chalcogenide thin film matrices

Nesheva

Hofmeister

Levi

et al. 2002

Vacuum

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Nanoparticles of CdSe embedded in amorphous SiO x , GeS 2 and polycrystalline ZnSe thin films have been produced by sequential physical vapour deposition of CdSe and one of the matrix materials. High-resolution electron microscopy has been used to prove the formation of CdSe nanoparticles. Particles with nearly spherical shape were observed whose spatial distribution follows the surface morphology of the 'matrix' films. The mechanism of nanoparticle formation on a rough surface has been discussed. It has been found that annealing of SiO x -CdSe films at 973 K leads to the formation of isolated CdSe nanoparticles homogeneously distributed in the matrix. Quantum-size increase in the optical band gap of CdSe nanoparticles has been observed in all matrices used. r

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Amorphous Se/CdSe and SiO x /CdSe multilayers

Cited by 2 publications

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Experimental studies on the defect states at the interface between nanocrystalline CdSe and amorphous SiO_x

Experimental studies on the defect states at the interface between nanocrystalline CdSe and amorphous SiO_x

Nanoparticle layers of CdSe buried in oxide and chalcogenide thin film matrices

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Amorphous Se/CdSe and SiO x /CdSe multilayers

Cited by 2 publications

References 0 publications

Experimental studies on the defect states at the interface between nanocrystalline CdSe and amorphous SiOx

Experimental studies on the defect states at the interface between nanocrystalline CdSe and amorphous SiOx

Nanoparticle layers of CdSe buried in oxide and chalcogenide thin film matrices

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Product

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Experimental studies on the defect states at the interface between nanocrystalline CdSe and amorphous SiO_x

Experimental studies on the defect states at the interface between nanocrystalline CdSe and amorphous SiO_x