03 March 2014


A. R. GoñiL. R. MunizJ. S. ReparazM. I. AlonsoM. GarrigaA. F. LopeandiaJ. Rodríguez-ViejoJ. Arbiol, and R. Rurali

Phys. Rev. B 89, 045428 – Published 28 January 2014


Regarding light absorption/emission efficiency, silicon presents the fundamental drawback of its indirect band gap. It is long known, though, that optical properties are greatly enhanced in materials which comprise different kinds of nanocrystalline Si covered by or embedded in Si oxide layers. Conversely, their amorphous counterparts have received far less attention, such that no general consensus about the emission mechanism prevails. We report here on an efficiently luminescent material based on amorphous Si nanoparticles (a-Si NPs) embedded in a nonstoichiometric Si oxide matrix, which exhibits intense, broadband emission from the a-Si NPs, spectrally separable from the defect luminescence of the suboxide matrix. Apart from the brightness of the emitted light, the nanometer-size a-Si inclusions present the technological advantage of needing very moderate annealing temperatures (450C–700C) for their production. The combined use of high pressure, experimentally as well as theoretically, allowed us to trace back the microscopic origin of the photoluminescence to radiative recombination processes between confined states of the a-Si NPs. The signature of quantum confinement is found in the magnitude and sign of the pressure coefficient of different optical transition energies. The pressure derivatives exhibit a universal dependence on particle size, determined solely by the confinement energy of the discrete electron state involved in the radiative recombination process.

Hits: 5742
Oxides for new-generation electronics

Using high pressure to unravel the mechanism of visible emission in amorphous Si/SiOx nanoparticles

Also at ICMAB

  • Epitaxial Ferroelectric HfO2 Films: Growth, Properties, and Devices

    25 May 2021 207 hit(s) Oxides
    About ten years after ferroelectricity was first reported in doped HfO2 polycrystalline films, there is tremendous interest in this material and ferroelectric oxides are once again in the spotlight of the memories industry. Great efforts are being made to understand and control ferroelectric properties. Epitaxial films, which have fewer defects and a more controlled microstructure than polycrystalline films, can be very useful for this purpose. Epitaxial films of ferroelectric HfO2 have been much less investigated, but after the first report in 2015 significant progress has been achieved.
  • Structure and phase transitions in A-site ordered RBaMn2O6(R=Pr,Nd) -perovskites with a polar ground state

    14 May 2021 225 hit(s) Oxides
    We report here a structural study of RBaMn2O6 (R=La, Pr, and Nd) compounds by means of synchrotron radiation x-ray powder diffraction and Raman spectroscopy. The three compounds are A-site ordered perovskites adopting the prototypical tetragonal structure at high temperature. A ferromagnetic transition is observed in the LaBaMn2O6 sample and the lattice parameters undergo anisotropic changes at TC related to the orientation of the magnetic moments.
  • Tuning the tilting of the spiral plane by Mn doping in YBaCuFeO5 multiferroic

    23 April 2021 304 hit(s) Oxides
    The layered perovskite YBaCuFeO5 (YBCFO) is considered one of the best candidates to high-temperature chiral multiferroics with strong magnetoelectric coupling. In RBaCuFeO5 perovskites (R: rare-earth or Y) A-site cations are fully ordered whereas their magnetic properties strongly depend on the preparation process. They exhibit partial cationic disorder at the B-site that generates a magnetic spiral stabilized through directionally assisted long range coupling between canted locally frustrated spins.
  • New Sensitive and Selective Chemical Sensors for Ni2+ and Cu2+ Ions: Insights into the Sensing Mechanism through DFT Methods

    09 April 2021 346 hit(s) Oxides
    We report the synthesis and theoretical study of two new colorimetric chemosensors with special selectivity and sensitivity to Ni2+ and Cu2+ ions over other metal cations in the CH3CN/H2O solution. Compounds (E)-4-((2-nitrophenyl)diazenyl)-N,N-bis(pyridin-2-ylmethyl)aniline (A) and (E)-4-((3-nitrophenyl)diazenyl)-N,N-bis(pyridin-2-ylmethyl)aniline (B) exhibited a drastic color change from yellow to colorless, which allows the detection of the mentioned metal cations through different techniques.
  • Silicon nanowires as acetone-adsorptive media for diabetes diagnosis

    06 April 2021 456 hit(s) Oxides
    Early detection of diabetes, a worldwide health issue, is key for its successful treatment. Acetone is a marker of diabetes, and efficient, non-invasive detection can be achieved with the use of nanotechnology. In this paper we investigate the effect of acetone adsorption on the electronic properties of silicon nanowires (SiNWs) by means of density functional theory.

INSTITUT DE CIÈNCIA DE MATERIALS DE BARCELONA, Copyright © 2020 ICMAB-CSIC | Privacy Policy | This email address is being protected from spambots. You need JavaScript enabled to view it.