Enhancing Hydrogen Diffusion in Silica Matrix by Using Metal Ion Implantation to Improve the Emission Properties of Silicon Nanocrystals

Efficient silicon-based light emitters continue to be a challenge. A great effort has been made in photonics to modify silicon in order to enhance its light emission properties. In this aspect silicon nanocrystals (Si-NCs) have become the main building block of silicon photonic (modulators, waveguide, source, and detectors). In this work, we present an approach based on implantation of Ag (or Au) ions and a proper thermal annealing in order to improve the photoluminescence (PL) emission of Si-NCs embedded in SiO2. The Si-NCs are obtained by ion implantation at MeV energy and nucleated at high depth into the silica matrix (1-2 μm under surface). Once Si-NCs are formed inside the SiO2we implant metal ions at energies that do not damage the Si-NCs. We have observed by, PL and time-resolved PL, that ion metal implantation and a subsequent thermal annealing in a hydrogen-containing atmosphere could significantly increase the emission properties of Si-NCs. Elastic Recoil Detection measurements show that the samples with an enhanced luminescence emission present a higher hydrogen concentration. This suggests that ion metal implantation enhances the hydrogen diffusion into silica matrix allowing a better passivation of surface defects on Si NCs.

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Characterization and light emission properties of β-FeSi2 precipitates in Si synthesized by metal vapor vacuum arc ion implantation

Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms ◽

10.1016/s0168-583x(03)00753-5 ◽

2003 ◽

Vol 206 ◽

pp. 317-320 ◽

Cited By ~ 10

Author(s):

Y. Gao ◽

S.P. Wong ◽

W.Y. Cheung ◽

G. Shao ◽

K.P. Homewood

Keyword(s):

Ion Implantation ◽

Light Emission ◽

Metal Vapor ◽

Vacuum Arc ◽

Emission Properties

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Hydrogen Passivation of Si Nanocrystals in Silica

MRS Proceedings ◽

10.1557/proc-650-r3.38 ◽

2000 ◽

Vol 650 ◽

Author(s):

Stephanie Cheylan ◽

Robert G. Elliman

Keyword(s):

Ion Implantation ◽

Thermal Annealing ◽

Silicon Nanocrystals ◽

Emission Spectra ◽

Red Shift ◽

High Dose ◽

Hydrogen Passivation ◽

High Fluence ◽

Si Nanocrystals ◽

Pl Emission

ABSTRACTThis paper explores the effect of hydrogen on the luminescence properties of silicon nanocrystals formed in silica by high-dose ion-implantation and thermal annealing. For samples implanted to low fluence (small nanocrystals), passivation is shown to result in a uniform enhancement of the PL emission for all wavelengths. However, for samples implanted to high fluence, preferential enhancement of the emission from larger nanocrystals is evident, resulting in a red-shift of emission spectra. Both the intensity enhancement and the red-shift are shown to be reversible, with spectra returning to their pre-passivation form when H is removed from the samples by annealing. The luminescence lifetime is also shown to increase after passivation, confirming that defect-containing nanocrystals luminesce.

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Luminescence of Silicon Nanocrystals in SiO2: Effects of Excitation Spectrum

MRS Proceedings ◽

10.1557/proc-777-t7.4 ◽

2003 ◽

Vol 777 ◽

Author(s):

A. Hryciw ◽

C.W. White ◽

K.H. Chow ◽

A. Meldrum

Keyword(s):

Ion Implantation ◽

Silicon Nanocrystals ◽

Light Emission ◽

Emission Spectra ◽

Excitation Power ◽

Fused Silica ◽

Peak Emission Wavelength ◽

Si Nanocrystals ◽

Recombination Processes ◽

High Pump

AbstractSilicon nanocrystals formed by ion implantation and annealing of fused silica wafers show a strong, broad photoluminescence (PL) peak centered at a wavelength between 750 and 900 nm, depending on the processing conditions. This luminescence has been extensively investigated and trial device structures based on these materials have been built. However, relatively few studies also report the optical absorption spectra. In fact, the absorbance of these specimens is quite low (usually < 10%) at wavelengths greater than 450 nm (i.e., at the pump wavelengths typically used for PL studies). This suggests that in numerous studies of Si nanocrystals produced by ion implantation, only a small fraction of the nanocrystals is responsible for the observed PL at the typical pump wavelengths. In this study, we investigated how the PL spectrum and intensity depend on the power and wavelength of the pump laser. We find that the PL intensity approaches saturation at high pump fluences, and that the peak emission wavelength is sensitive to the excitation power. These observations can be attributed to the dynamics of the excitation/recombination processes at different energies, and indicate that considerable care must be taken when comparing the emission spectra of different specimens. Our data are uniformly consistent with a mechanism of light emission involving subgap states (i.e., radiative trap sites) and are not supportive of a “pure” quantum confinement model.

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