Article

Si-rich Al2O3 films grown by RF magnetron sputtering: structural and photoluminescence properties versus annealing treatment

V, Lashkaryov Institute of Semiconductor Physics, 45 Pr, Nauky, 03028, Kyiv, Ukraine. .
Nanoscale Research Letters (Impact Factor: 2.52). 06/2013; 8(1):273. DOI: 10.1186/1556-276X-8-273
Source: PubMed

ABSTRACT Silicon-rich Al2O3 films (Six(Al2O3)1-x) were co-sputtered from two separate silicon and alumina targets onto a long silicon oxide substrate. The effects of different annealing treatments on the structure and light emission of the films versus x were investigated by means of spectroscopic ellipsometry, X-ray diffraction, micro-Raman scattering, and micro-photoluminescence (PL) methods. The formation of amorphous Si clusters upon the deposition process was found for the films with x ≥ 0.38. The annealing treatment of the films at 1,050°C to 1,150°C results in formation of Si nanocrystallites (Si-ncs). It was observed that their size depends on the type of this treatment. The conventional annealing at 1,150°C for 30 min of the samples with x = 0.5 to 0.68 leads to the formation of Si-ncs with the mean size of about 14 nm, whereas rapid thermal annealing of similar samples at 1,050°C for 1 min showed the presence of Si-ncs with sizes of about 5 nm. Two main broad PL bands were observed in the 500- to 900-nm spectral range with peak positions at 575 to 600 nm and 700 to 750 nm accompanied by near-infrared tail. The low-temperature measurement revealed that the intensity of the main PL band did not change with cooling contrary to the behavior expected for quantum confined Si-ncs. Based on the analysis of PL spectrum, it is supposed that the near-infrared PL component originates from the exciton recombination in the Si-ncs. However, the most intense emission in the visible spectral range is due to either defects in matrix or electron states at the Si-nc/matrix interface.

Full-text

Available from: Vasyl Peter Kladko, Jun 03, 2015
0 Followers
 · 
401 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Present work deals with the study of luminescence and structural properties of Y-doped ZrO2 nanopowders sintered by co-precipitation of Zr and Y nitrates. The structural and light emitting properties were controlled by X-ray diffraction, transmission electron microscopy, Raman scattering, photo- (PL) and cathodoluminescence (CL) methods. Generally, room temperature PL spectra showed several bands in UV-orange range, whose shapes depend on the excitation light wavelength. Along with this, CL spectra demonstrate additional “red” emission, which intensity exceeds that of other CL bands. At lower temperatures, preferable enhancement of “red” CL band, its narrowing and peak position shift to the longer wavelengths were found. This behavior testifies to the non-elementary nature of “red” CL band. Its nature and mechanism of its excitation are discussed. It is supposed that some impurities (such as Fe and/or Zn) or complex defects, containing oxygen vacancies and these impurities, are responsible for “red” emission appeared under electron beam excitation only. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
    physica status solidi (c) 09/2014; 11(9-10):1417-1422. DOI:10.1002/pssc.201300597
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Composite nanofibers consisting of Al2O3-SiO2 were prepared by electrospinning in combination with post-calcination in air. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy were used to investigate the crystalline phase and microstructure of the composite nanofibers. Photoluminescence experiments indicated that the resulting white light emission can be tuned by the relative intensity of the individual spectral components, which are related to the individual defects such as: violet-blue emission from O defects, green emission from ≡Si(Al)-O-C∙=O, and red emission from intersystem radiative crossing. White light emission was realized at a Al/(Al-Si) ratio of 40 and 60 mol %. This research may offer a deeper understanding of the preparation of efficient and environmentally friendly, white luminescence materials.
    Beilstein Journal of Nanotechnology 01/2015; 6:313–320. DOI:10.3762/bjnano.6.29 · 2.33 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This work presents the comparative investigation of Six(Al2O3)1-x and Six(SiO2)1-x films with different excess Si content, x, grown by RF magnetron sputtering. Their properties were investigated by means of Raman scattering, X-ray diffraction, Electron paramagnetic resonance and photoluminescence methods. As-deposited films with the x⩾0.3 were found to be two-phase systems that contained an amorphous Si phase. Contrary to Six(SiO2)1-x films, tensile stresses were observed for Six(Al2O3)1-x samples due to lattice mismatch between the film and quartz substrate. The Si nanocrystals (Si-ncs) were formed upon annealing at 1150°C for 30 min in nitrogen flow in both types of samples. Along with this, for the films with the x>0.3, amorphous Si phase was also detected, but its contribution was smaller in the Six(Al2O3)1-x films. Besides, the Si-ncs embedded in Al2O3 host remained under tensile stresses after annealing. For the films with the same x values, the Si-ncs in Al2O3 were found to be larger than those embedded in SiO2. Photoluminescence spectra showed that the main radiative channel in Six(SiO2)1-x films is exciton recombination in Si-ncs, while in Six(Al2O3)1-x films the defect related emission prevails due to higher amount of interface defects in the Six(Al2O3)1-x. The nature of these defects is discussed.
    Microelectronic Engineering 02/2014; 125(8):62-67. DOI:10.1016/j.mee.2013.12.001 · 1.34 Impact Factor