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A new study investigates the mechanical stress in thermally grown SiO2 films on Si during 4 Me V Xe ion irradiation.

Depth-resolved measurements of the photoluminescence of Si implanted and annealed SiO2 films on Si were conducted to obtain the depth distribution of luminescent Si nanocrystals. It was observed that the defect luminescence centered around lambda = 600 nm mostly comes from a approximately 15 m-thick near-surface region. Large Si nanocrystals emitting at lambda = 900 nm were mostly found in the center of the oxide film, where the Si concentration was highest.

The concept of a nanowire solar cell with photon-harvesting shells is described and the organic molecules that absorb strongly in the near infrared where silicon absorbs weakly are coupled to silicon nanowires (SiNWs). The organic molecules have absorbed the low-energy photons and have subsequently transferred the energy to the SiNWs via Forster resonant energy transfer, creating free electrons and holes within the SiNWs.

Determines the mechanical stress in thermally grown silica films on silicon during 4 millielectron volt xenon ion irradiation. Observation of the radiation induced viscous flow; Determination of the radiation induced viscosity; Explanation of the magnetic and temperature dependence by phenomenological model.

Silicon nanocrystals were formed in SiO[sub 2] using Si ion implantation followed by thermal annealing. The nanocrystal-doped SiO[sub 2] layer was implanted with Er to a peak concentration of 1.8 at. %. Upon 458 nm excitation the sample shows a broad nanocrystal-related luminescence spectrum centered around 750 nm and two sharp Er luminescence lines at 982 and 1536 nm. By measuring the excitation spectra of these features as well as the temperature-dependent intensities and luminescence dynamics we conclude that (a) the Er is excited by excitons recombining within Si nanocrystals through a strong coupling mechanism, (b) the Er excitation process at room temperature occurs at a submicrosecond time scale, (c) excitons excite Er with an efficiency >55%, and (d) each nanocrystal can have at most ∼1 excited Er ion in its vicinity. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]