The optoelectronic properties of titania–germanium nanocomposites

Chatterjee, Sourav

doi:10.1088/0022-3727/41/5/055301

Cited by 12 publications

(12 citation statements)

References 40 publications

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“…A similar E opt g has been reported in the literature only for one sample containing Ge QDs in a TiO 2 matrix [23], without variation of annealing temperature or structural phase. In order to account for the E opt g of QDs, quantum confinement effect can be invoked since the size is well below the excitonic Bohr radius.…”

Section: Resultssupporting

confidence: 83%

The role of the surfaces in the photon absorption in Ge nanoclusters embedded in silica

et al. 2011

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The usage of semiconductor nanostructures is highly promising for boosting the energy conversion efficiency in photovoltaics technology, but still some of the underlying mechanisms are not well understood at the nanoscale length. Ge quantum dots (QDs) should have a larger absorption and a more efficient quantum confinement effect than Si ones, thus they are good candidate for third-generation solar cells. In this work, Ge QDs embedded in silica matrix have been synthesized through magnetron sputtering deposition and annealing up to 800°C. The thermal evolution of the QD size (2 to 10 nm) has been followed by transmission electron microscopy and X-ray diffraction techniques, evidencing an Ostwald ripening mechanism with a concomitant amorphous-crystalline transition. The optical absorption of Ge nanoclusters has been measured by spectrophotometry analyses, evidencing an optical bandgap of 1.6 eV, unexpectedly independent of the QDs size or of the solid phase (amorphous or crystalline). A simple modeling, based on the Tauc law, shows that the photon absorption has a much larger extent in smaller Ge QDs, being related to the surface extent rather than to the volume. These data are presented and discussed also considering the outcomes for application of Ge nanostructures in photovoltaics.PACS: 81.07.Ta; 78.67.Hc; 68.65.-k

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Section: Resultssupporting

confidence: 83%

The role of the surfaces in the photon absorption in Ge nanoclusters embedded in silica

et al. 2011

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“…1a-d), is consistent with the formation of a more isolated Ge nanocrystal phase, modifying the geometry of the carrier confinement region. This effect has been observed previously in other host matrices [11,15,16]. The consistency of this effect in an embedding material anticipated to provide little energetic confinement of electrons based on bulk electron affinity values (E a (ITO)= 4.1 À 4.5 eV; E a (Ge)= 4.0 eV) [17], suggests the presence of a low E a interfacial phase.…”

Section: Discussionsupporting

confidence: 79%

RF-sputtered Ge–ITO nanocomposite thin films for photovoltaic applications

Shih

Allen

Potter

2010

Solar Energy Materials and Solar Cells

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“…Electronegativity of Ti is smaller (1.54 Pauling) than that of Ge (2.01 Pauling), and the enthalpy of formation of TiO 2 is lower (ΔH f = −944KJ·mol -1 ) than that of GeO 2 (ΔH f = −580KJ·mol -1 ). Hence, in the presence of oxygen, Ti is preferentially oxidized, leaving Ge in elemental form [11].…”

Section: Characterizationmentioning

confidence: 99%

Influence of the deposition conditions on the properties of TiO<inf>2</inf> -Ge nanocomposite films synthesized by magnetron co-sputtering

Slav

Stan

Gâlcă

2010

CAS 2010 Proceedings (International Semiconductor Conference)

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A growing need for eco-friendly energy sources have led recently to a frantic search of new compositional systems for photovoltaic applications. The nanocomposite titania-germanium (TiO 2 -Ge) systems represent a new viable family of optoelectronic materials. Their structural, optical and electronic properties can be easily tailored by customizing the density and size of Ge dots in the TiO 2 matrix. Early studies on TiO 2 -Ge nanocomposites have shown promises for their use as an alternative in photovoltaic applications. In this study we report the TiO 2 -Ge films synthesis by reactive magnetron co-sputtering. Their properties were evaluated by compositional (EDS), structural (XRD, FTIR) and optical (UV-Vis) characterizations.

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The optoelectronic properties of titania–germanium nanocomposites

Cited by 12 publications

References 40 publications

The role of the surfaces in the photon absorption in Ge nanoclusters embedded in silica

The role of the surfaces in the photon absorption in Ge nanoclusters embedded in silica

RF-sputtered Ge–ITO nanocomposite thin films for photovoltaic applications

Influence of the deposition conditions on the properties of TiO<inf>2</inf> -Ge nanocomposite films synthesized by magnetron co-sputtering

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