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Thickness-dependent optimization of Er3+ light emission from silicon-rich silicon oxide thin films.

Cueff S, Labbé C, Jambois O, Garrido B, Portier X, Rizk R - Nanoscale Res Lett (2011)

Bottom Line: The Er3+ photoluminescence at 1.5 μm, normalized to the film thickness, was found five times larger for films 1 μm-thick than that from 50-nm-thick films intended for electrically driven devices.More Si excess has significantly increased the emission from "thin" films, up to ten times.This paves the way to the realization of highly efficient electrically excited devices.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centre de Recherche sur les Ions, les Matériaux et la Photonique (CIMAP), ENSICAEN, CNRS, CEA/IRAMIS, Université de Caen, 14050 CAEN cedex, France. richard.rizk@ensicaen.fr.

ABSTRACT
This study investigates the influence of the film thickness on the silicon-excess-mediated sensitization of Erbium ions in Si-rich silica. The Er3+ photoluminescence at 1.5 μm, normalized to the film thickness, was found five times larger for films 1 μm-thick than that from 50-nm-thick films intended for electrically driven devices. The origin of this difference is shared by changes in the local density of optical states and depth-dependent interferences, and by limited formation of Si-based sensitizers in "thin" films, probably because of the prevailing high stress. More Si excess has significantly increased the emission from "thin" films, up to ten times. This paves the way to the realization of highly efficient electrically excited devices.

No MeSH data available.


Related in: MedlinePlus

Typical XPS spectra obtained on the sample deposited at 500°C and about 150 nm thick. In (a) is displayed the O 1s spectrum and (b) corresponds to Si 2p spectrum. The inset of (b) depicts the profile of %Si excess versus depth.
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Figure 1: Typical XPS spectra obtained on the sample deposited at 500°C and about 150 nm thick. In (a) is displayed the O 1s spectrum and (b) corresponds to Si 2p spectrum. The inset of (b) depicts the profile of %Si excess versus depth.

Mentions: Typical Si 2p and O 1s XPS spectra of the sample deposited at 500°C for 1 h are displayed in Figure 1. The values of Si excess were determined by measurement of the ratios of the atomic concentration of Si and O (x = [O]/[Si]), that were deduced from the area of the Si 2p and O 1s spectra and compared to a stoichiometric SiO2 sample. The XPS measurements are performed while etching the sample with Ar in the same time, allowing the determination of the Si excess depth profile. The reported values correspond to the value read in the flat region (see inset Figure 1b). For the thinner layer, the thickness is still large enough to be able to obtain a good depth resolution. The flatness of the profiles along almost the whole thickness demonstrates that the thickness of the material has no influence on the stoichiometry of the deposited SiOx. However, the x parameter was found to increase from x = 1.555 ± 0.004 for RT-deposited samples to x = 1.616 ± 0.009 for Td = 500°C. This reflects a lowering of Si excess due to the increasing desorption of SiO with Td, as observed in our recent work [12]. For the FTIR approach, which is based on the shift of the TO3 peak towards that of stoichiometric SiO2 [13], the detection of Si excess is limited to the Si atoms bonded to O, and does not take into account the agglomerated Si atoms [13]. However, this limitation can be used to advantage by comparing values of Si excess measured by FTIR to those determined by XPS, enabling evaluation of the fraction of agglomerated Si. Since the phase separation between Si and SiO2 is incomplete for the as-deposited samples, the following relation holds:(1)


Thickness-dependent optimization of Er3+ light emission from silicon-rich silicon oxide thin films.

Cueff S, Labbé C, Jambois O, Garrido B, Portier X, Rizk R - Nanoscale Res Lett (2011)

Typical XPS spectra obtained on the sample deposited at 500°C and about 150 nm thick. In (a) is displayed the O 1s spectrum and (b) corresponds to Si 2p spectrum. The inset of (b) depicts the profile of %Si excess versus depth.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211489&req=5

Figure 1: Typical XPS spectra obtained on the sample deposited at 500°C and about 150 nm thick. In (a) is displayed the O 1s spectrum and (b) corresponds to Si 2p spectrum. The inset of (b) depicts the profile of %Si excess versus depth.
Mentions: Typical Si 2p and O 1s XPS spectra of the sample deposited at 500°C for 1 h are displayed in Figure 1. The values of Si excess were determined by measurement of the ratios of the atomic concentration of Si and O (x = [O]/[Si]), that were deduced from the area of the Si 2p and O 1s spectra and compared to a stoichiometric SiO2 sample. The XPS measurements are performed while etching the sample with Ar in the same time, allowing the determination of the Si excess depth profile. The reported values correspond to the value read in the flat region (see inset Figure 1b). For the thinner layer, the thickness is still large enough to be able to obtain a good depth resolution. The flatness of the profiles along almost the whole thickness demonstrates that the thickness of the material has no influence on the stoichiometry of the deposited SiOx. However, the x parameter was found to increase from x = 1.555 ± 0.004 for RT-deposited samples to x = 1.616 ± 0.009 for Td = 500°C. This reflects a lowering of Si excess due to the increasing desorption of SiO with Td, as observed in our recent work [12]. For the FTIR approach, which is based on the shift of the TO3 peak towards that of stoichiometric SiO2 [13], the detection of Si excess is limited to the Si atoms bonded to O, and does not take into account the agglomerated Si atoms [13]. However, this limitation can be used to advantage by comparing values of Si excess measured by FTIR to those determined by XPS, enabling evaluation of the fraction of agglomerated Si. Since the phase separation between Si and SiO2 is incomplete for the as-deposited samples, the following relation holds:(1)

Bottom Line: The Er3+ photoluminescence at 1.5 μm, normalized to the film thickness, was found five times larger for films 1 μm-thick than that from 50-nm-thick films intended for electrically driven devices.More Si excess has significantly increased the emission from "thin" films, up to ten times.This paves the way to the realization of highly efficient electrically excited devices.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centre de Recherche sur les Ions, les Matériaux et la Photonique (CIMAP), ENSICAEN, CNRS, CEA/IRAMIS, Université de Caen, 14050 CAEN cedex, France. richard.rizk@ensicaen.fr.

ABSTRACT
This study investigates the influence of the film thickness on the silicon-excess-mediated sensitization of Erbium ions in Si-rich silica. The Er3+ photoluminescence at 1.5 μm, normalized to the film thickness, was found five times larger for films 1 μm-thick than that from 50-nm-thick films intended for electrically driven devices. The origin of this difference is shared by changes in the local density of optical states and depth-dependent interferences, and by limited formation of Si-based sensitizers in "thin" films, probably because of the prevailing high stress. More Si excess has significantly increased the emission from "thin" films, up to ten times. This paves the way to the realization of highly efficient electrically excited devices.

No MeSH data available.


Related in: MedlinePlus