Photoluminescence and passivation of silicon nanostructures
ABSTRACT A new method was used to fabricate nanometer‐scale structures in Si for photoluminescence studies. Helium ions were implanted to form a dense subsurface layer of small cavities (1–16 nm diameter). Implanted specimens subjected to annealing in a variety of atmospheres yielded no detectable photoluminescence. However, implantation combined with electrochemical anodization produced a substantial blueshift relative to anodization alone. This blueshift is consistent with the quantum confinement model of photoluminescence in porous silicon.
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ABSTRACT: An approximate continuum method for computing the energy of interaction between cavities and strain fields in complex configurations is described and tested by comparison with results for simple, exactly solvable cases. The method is then used to examine semiquantitatively the effective forces between cavities and screw and edge dislocations, taking into account the effects of surface tension and pressurized gas within the cavity. The discussion encompasses not only local interactions involving individual cavities, but also the combined forces acting upon dislocations in the vicinity of multiple cavities and simultaneously within range of external-surface image forces. The results are used to interpret a range of observed microstructures in semiconductors and to assess the possible exploitation of cavity–dislocation binding for dislocation control in Si–Ge heteroepitaxial structures. © 1999 American Institute of Physics.Journal of Applied Physics 09/1999; 86(6):3048-3063. · 2.19 Impact Factor
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ABSTRACT: We report the observation of visible and stable room temperature photoluminescence (PL) from thin composite films deposited onto various substrates (Si, SiO2, Al and C) by means of an ion-beam sputtering system. Transmission electron microscopy (TEM) observations of the films deposited on carbon substrates reveal the presence of filamentary structures, with nanometric dimensions, of crystalline silicon embedded in an amorphous matrix. While changes of film composition do not influence the main features of the PL, we found that the PL shape and intensity is strongly dependent on the nature of the substrate. The necessary combination of Si and SiO2 for producing the light-emitting material and the TEM results suggest that quantum confinement of carriers in the silicon nanocrystals is a possible origin of the observed PL.Solid State Communications 11/1996; 100(6):403-406. · 1.70 Impact Factor
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ABSTRACT: Although porous silicon (pSi) was first obtained in the mid-20th century, considerable interest in this material arose much later, due to the discovery of its room-temperature photoluminescence (PL). In the 1990s, most studies on pSi were focused on the analysis and explanation of its photoluminescent and electroluminescent characteristics and their potential practical applications. The latest advances in pSi research are related to its biocompatibility and biomedical applications. The discovery of singlet oxygen generation by pSi through nonradiative transfer of photoexcitation energy has opened new prospects for photodynamic therapy in vivo, and the discovery of laser desorption/ionization on pSi has paved the way for advanced approaches in mass-spectrometry. In this study, the main photophysical properties of pSi are reviewed, and a wide range of photo-processes characteristic of pSi and their practical implications are analyzed in terms of the general principles of energy and charge transfer. Special attention is paid to the possible applications of pSi and pSi-based nanocomposites in photonics, biophysics, medicine, and analytical chemistry.Physical Chemistry Chemical Physics 09/2012; 14(40):13890-902. · 4.20 Impact Factor