Evidence for fast decay dynamics of the photoluminescence from Ge nanocrystals embedded in SiO2

Giri, P. K.; Kesavamoorthy, R.; Panigrahi, B. K.; Nair, K. G. M.

doi:10.1016/j.ssc.2004.11.007

Cited by 38 publications

(38 citation statements)

References 32 publications

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“…This value is close to the onset absorption of 1.0 eV at 1.5 at.% Ge (Figure 5). Ge nanocrystals embedded in silica matrix also exhibits similar optical absorption spectrum, with the mean size of 6.0 nm estimated from direct observation using high-resolution transmission microscopy [22]. Consequently, the shift of the optical absorption edge (Figure 5) is reasonably due to the presence of Ge nanocrystals embedded in the Nb 2 O 5 matrix.…”

Section: Resultssupporting

confidence: 53%

Formation of Nb2O5 matrix and Vis-NIR absorption in Nb-Ge-O thin film

Abe

2012

Nanoscale Res Lett

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This paper investigates the crystal structure and optical absorption of Ge-doped Nb-oxide (Nb-Ge-O) thin films prepared by RF sputtering. A wide-gap material, Nb2O5, is selectively produced as a matrix to disperse Ge nanocrystals through compositional optimization with Ge chip numbers and oxygen ratio in argon. The optical-absorption spectra are obviously shifted to visible (vis) and near-infrared (NIR) regions, suggesting that a composite thin film with Ge nanocrystals dispersed in Nb2O5 matrix exhibits quantum-size effects. Accordingly, the two valuable characteristics of the Nb2O5 matrix and the vis-NIR absorption are found to be retained simultaneously in Nb-Ge-O thin films.

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Section: Resultssupporting

confidence: 53%

Formation of Nb2O5 matrix and Vis-NIR absorption in Nb-Ge-O thin film

Abe

2012

Nanoscale Res Lett

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“…Similar fast PL decay dynamics was observed for visible PL from Ge NCs prepared by ion-implantation. 20 A fast (∼4 ns) decay dynamics was observed for the UV PL from defects in porous silica. 21 Zacharias and Fauchet observed a nanosecond PL dynamics for the ∼400 nm band in sputter deposited Ge NCs and the fast response was attributed to defects at the nanocrystal/matrix interface.…”

Section: Pl Excitation Spectroscopymentioning

confidence: 93%

Intense Ultraviolet-Blue Photoluminescence from SiO₂ Embedded Ge Nanocrystals Prepared by Different Techniques

Giri¹,

Bhattacharyya²,

Kesavamoorthy³

et al. 2009

j nanosci nanotechnol

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We have made systematic studies on the ultraviolet-blue photoluminescence (PL) from Ge nanocrystals (NCs) grown embedded in SiO 2 matrix. Embedded Ge NCs are grown by two different methods, namely, radio-frequency magnetron sputtering (SPT) and ion implantation (IMP). For comparison, Ar implanted SiO 2 layer was processed similarly and studied to isolate the contribution of Ge atoms in the observed PL. X-ray diffraction, optical Raman and low frequency Raman scattering studies confirm the presence of Ge NCs in samples prepared by SPT and IMP methods and Si nanoclusters in Ar implanted sample. Room temperature PL studies with 325 nm excitation show very strong UV-blue emission bands in the range 342-420 nm, and PL studies with 246 nm excitation show two strong UV emission bands at ∼285 nm and ∼393 nm in implanted samples. Deconvolution of UV-blue bands show that most of the emission peaks are not unique to the presence of Ge in the samples. Time resolved PL studies in the blue wavelength region show a fast decay dynamics (time constant of ∼1.0 ns), irrespective of the NC size. PL excitation spectroscopy measurements show a large Stoke's shift for the UV emission bands. Our results indicate that contrary to the literature reports, the ∼400 nm PL emission is band is not unique to the presence of Ge in the SiO 2 matrix and it is likely to originate from a defective NC/SiO 2 interface, irrespective of the species of NCs. Origin of various UV emission bands is discussed in the light of the experimental findings and literature reports.

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“…In our previous work, we demonstrated that the PL peak is sensitive to the size of nanocrystals. From the observed size dependence, we attribute the peak to the recombination of electrons and holes confined in the nc-Ge [18][19][20]. Moreover, in low-energy side of PL, nc-Ge shows a weak peak at 780 nm, which does not shift as the size of nc-Ge decreases.…”

Section: Methodsmentioning

confidence: 80%

Effect of As doping on the photoluminescence of nanocrystalline 74Ge embedded in SiO2 matrix

Dun

et al. 2008

Journal of Luminescence

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Evidence for fast decay dynamics of the photoluminescence from Ge nanocrystals embedded in SiO2

Cited by 38 publications

References 32 publications

Formation of Nb2O5 matrix and Vis-NIR absorption in Nb-Ge-O thin film

Formation of Nb2O5 matrix and Vis-NIR absorption in Nb-Ge-O thin film

Intense Ultraviolet-Blue Photoluminescence from SiO₂ Embedded Ge Nanocrystals Prepared by Different Techniques

Effect of As doping on the photoluminescence of nanocrystalline 74Ge embedded in SiO2 matrix

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Evidence for fast decay dynamics of the photoluminescence from Ge nanocrystals embedded in SiO2

Cited by 38 publications

References 32 publications

Formation of Nb2O5 matrix and Vis-NIR absorption in Nb-Ge-O thin film

Formation of Nb2O5 matrix and Vis-NIR absorption in Nb-Ge-O thin film

Intense Ultraviolet-Blue Photoluminescence from SiO2 Embedded Ge Nanocrystals Prepared by Different Techniques

Effect of As doping on the photoluminescence of nanocrystalline 74Ge embedded in SiO2 matrix

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Intense Ultraviolet-Blue Photoluminescence from SiO₂ Embedded Ge Nanocrystals Prepared by Different Techniques