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Structural origin of light emission in germanium quantum dots.

Little W, Karatutlu A, Bolmatov D, Trachenko K, Sapelkin AV, Cibin G, Taylor R, Mosselmans F, Dent AJ, Mountjoy G - Sci Rep (2014)

Bottom Line: Two sets of nanoparticles were studied, with oxygen and hydrogen terminated surfaces.We found that in oxygen terminated nanoparticles its the oxide-rich regions that are responsible for the light emission.In hydrogen terminated nanoparticles we established that structurally disordered Ge regions contribute to the luminescence.

View Article: PubMed Central - PubMed

Affiliation: Center for Condensed Matter and Materials Physics, School of Physics and Astronomy, Queen Mary, University of London, Mile End Road, London E1 4NS, UK.

ABSTRACT
We used a combination of optically-detected x-ray absorption spectroscopy with molecular dynamics simulations to explore the origins of light emission in small (5 nm to 9 nm) Ge nanoparticles. Two sets of nanoparticles were studied, with oxygen and hydrogen terminated surfaces. We show that optically-detected x-ray absorption spectroscopy shows sufficient sensitivity to reveal the different origins of light emission in these two sets of samples. We found that in oxygen terminated nanoparticles its the oxide-rich regions that are responsible for the light emission. In hydrogen terminated nanoparticles we established that structurally disordered Ge regions contribute to the luminescence. Using a combination of molecular dynamics simulations and optically-detected x-ray absorption spectroscopy we show that these disordered regions correspond to the disordered layer a few Å thick at the surface of the simulated nanoparticle.

No MeSH data available.


A schematic diagram of the x-ray excitation-photoluminescence cycle in OD-XAS.An excitation from a 1 s state to continuum followed by radiative recombination (XEOL) that carries information about a XAS event.
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f1: A schematic diagram of the x-ray excitation-photoluminescence cycle in OD-XAS.An excitation from a 1 s state to continuum followed by radiative recombination (XEOL) that carries information about a XAS event.

Mentions: One technique that is capable of linking light emission directly with the structure is optically-detected XAS (OD-XAS). OD-XAS is a technique that enables structural data to be obtained directly from x-ray excited optical luminescence (XEOL) and has already been used to address the origins of PL in pSi61920. OD-XAS is based on sensitivity of the XEOL signal to photoelectron generation in the x-ray absorption process near and above the x-ray absorption edge of an element (see Fig. 1). The XEOL-related x-ray absorption signal is measured by recording the integral photoluminescence yield within a selected wavelength range. Thus, OD-XAS is sensitive to a subset of sites related to the light emission. Despite its capabilities, OD-XAS could not provide an unambiguous answer as to the origins of PL in pSi. One of the main reasons for that is the sensitivity of OD-XAS to the sample preparation methods2122 which precluded wider use of the technique. Another difficulty is in assessing the spatial sensitivity of this method on the scale of a few nm1920.


Structural origin of light emission in germanium quantum dots.

Little W, Karatutlu A, Bolmatov D, Trachenko K, Sapelkin AV, Cibin G, Taylor R, Mosselmans F, Dent AJ, Mountjoy G - Sci Rep (2014)

A schematic diagram of the x-ray excitation-photoluminescence cycle in OD-XAS.An excitation from a 1 s state to continuum followed by radiative recombination (XEOL) that carries information about a XAS event.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4260222&req=5

f1: A schematic diagram of the x-ray excitation-photoluminescence cycle in OD-XAS.An excitation from a 1 s state to continuum followed by radiative recombination (XEOL) that carries information about a XAS event.
Mentions: One technique that is capable of linking light emission directly with the structure is optically-detected XAS (OD-XAS). OD-XAS is a technique that enables structural data to be obtained directly from x-ray excited optical luminescence (XEOL) and has already been used to address the origins of PL in pSi61920. OD-XAS is based on sensitivity of the XEOL signal to photoelectron generation in the x-ray absorption process near and above the x-ray absorption edge of an element (see Fig. 1). The XEOL-related x-ray absorption signal is measured by recording the integral photoluminescence yield within a selected wavelength range. Thus, OD-XAS is sensitive to a subset of sites related to the light emission. Despite its capabilities, OD-XAS could not provide an unambiguous answer as to the origins of PL in pSi. One of the main reasons for that is the sensitivity of OD-XAS to the sample preparation methods2122 which precluded wider use of the technique. Another difficulty is in assessing the spatial sensitivity of this method on the scale of a few nm1920.

Bottom Line: Two sets of nanoparticles were studied, with oxygen and hydrogen terminated surfaces.We found that in oxygen terminated nanoparticles its the oxide-rich regions that are responsible for the light emission.In hydrogen terminated nanoparticles we established that structurally disordered Ge regions contribute to the luminescence.

View Article: PubMed Central - PubMed

Affiliation: Center for Condensed Matter and Materials Physics, School of Physics and Astronomy, Queen Mary, University of London, Mile End Road, London E1 4NS, UK.

ABSTRACT
We used a combination of optically-detected x-ray absorption spectroscopy with molecular dynamics simulations to explore the origins of light emission in small (5 nm to 9 nm) Ge nanoparticles. Two sets of nanoparticles were studied, with oxygen and hydrogen terminated surfaces. We show that optically-detected x-ray absorption spectroscopy shows sufficient sensitivity to reveal the different origins of light emission in these two sets of samples. We found that in oxygen terminated nanoparticles its the oxide-rich regions that are responsible for the light emission. In hydrogen terminated nanoparticles we established that structurally disordered Ge regions contribute to the luminescence. Using a combination of molecular dynamics simulations and optically-detected x-ray absorption spectroscopy we show that these disordered regions correspond to the disordered layer a few Å thick at the surface of the simulated nanoparticle.

No MeSH data available.