Nanocrystal and interface defects related photoluminescence in silicon-rich Al2O3 films

Bi, Lei; Feng, Jian

doi:10.1016/j.jlumin.2005.10.007

Cited by 33 publications

(17 citation statements)

References 29 publications

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“…The obtained spectra were converted by the Kubelka-Munk function F(R) into absorption spectra, using BaSO 4 as a white standard. Optical band gaps (E g ) were obtained via the Tauc-plot method [15][16][17][18][19] using the calculation α = A(hν − E g ) n /hν, where α is the absorption coefficient, A is a constant, hν is the energy of light, and n = 2 or 0.5 for materials with indirect or direct transition, respectively. Assuming the absorption coefficient α being proportional to the KubelkaMunk function F(R), the E g can be obtained from the plot of [F(R)hν] 1/n versus hν, by extrapolation of the linear part near the onset of the absorption edge to intersect the energy axis.…”

Section: Synthesis Of Materialsmentioning

confidence: 99%

Enhanced photocatalytic hydrogen generation from barium tantalate composites

Marschall

Soldat

Wark

2013

Photochem Photobiol Sci

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(111)-layered Ba5Ta4O15 photocatalysts were synthesised by a solid state reaction route and a citrate synthesis route, and their structural and electronic properties were investigated. After citrate route preparation, the presence of a second phase, namely Ba3Ta5O15, was determined by X-ray powder diffraction and absorption spectroscopy. The existence of this phase had a profound effect on the photocatalytic activity of this Ba5Ta4O15/Ba3Ta5O15 composite in comparison to the pure Ba5Ta4O15 materials. The photocatalytic performance of the barium tantalates was evaluated by investigating the capability in ˙OH radical formation and hydrogen generation. Strongly increased hydrogen evolution rates for the Ba5Ta4O15/Ba3Ta5O15 composite, up to 160% higher than for the pure Ba5Ta4O15, were determined, and only very small amounts of Rh co-catalyst, deposited on the photocatalysts by stepwise reductive photo-deposition, were needed to achieve these results.

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Section: Synthesis Of Materialsmentioning

confidence: 99%

Enhanced photocatalytic hydrogen generation from barium tantalate composites

Marschall

Soldat

Wark

2013

Photochem Photobiol Sci

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“…[16]. The broad PL spectrum can be considered as overlapping of several PL bands (similar to the case of CA treatment).…”

Section: Resultsmentioning

confidence: 99%

“…For these systems, the successful Si-nc formation was already demonstrated. However, in spite of the relative simplicity of magnetron sputtering technique and its wide application for the fabrication of Si-rich SiO 2 materials [5,8], only few groups applied this method for deposition of Si-rich alumina [16]. …”

Section: Introductionmentioning

confidence: 99%

Si-rich Al2O3 films grown by RF magnetron sputtering: structural and photoluminescence properties versus annealing treatment

et al. 2013

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Silicon-rich Al2O3 films (Six(Al2O3)1−x) were co-sputtered from two separate silicon and alumina targets onto a long silicon oxide substrate. The effects of different annealing treatments on the structure and light emission of the films versus x were investigated by means of spectroscopic ellipsometry, X-ray diffraction, micro-Raman scattering, and micro-photoluminescence (PL) methods. The formation of amorphous Si clusters upon the deposition process was found for the films with x ≥ 0.38. The annealing treatment of the films at 1,050°C to 1,150°C results in formation of Si nanocrystallites (Si-ncs). It was observed that their size depends on the type of this treatment. The conventional annealing at 1,150°C for 30 min of the samples with x = 0.5 to 0.68 leads to the formation of Si-ncs with the mean size of about 14 nm, whereas rapid thermal annealing of similar samples at 1,050°C for 1 min showed the presence of Si-ncs with sizes of about 5 nm. Two main broad PL bands were observed in the 500- to 900-nm spectral range with peak positions at 575 to 600 nm and 700 to 750 nm accompanied by near-infrared tail. The low-temperature measurement revealed that the intensity of the main PL band did not change with cooling contrary to the behavior expected for quantum confined Si-ncs. Based on the analysis of PL spectrum, it is supposed that the near-infrared PL component originates from the exciton recombination in the Si-ncs. However, the most intense emission in the visible spectral range is due to either defects in matrix or electron states at the Si-nc/matrix interface.

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“…The stresses, which bring about the breaking of chem ical bonds and the generation of nonradiative recom bination centers, can be responsible for the absence of typical photoluminescence (in the wavelength range 650-900 nm) of Si nanocrystals formed in the crystal line Al 2 O 3 (sapphire) matrix [10,11]. At the same time, the film variant of the Al 2 O 3 : NC Si system exhibits a characteristic photoluminescence in the near infrared (IR) spectral region, which is associ ated, in particular, with the possibility of oxidizing the surface of Si nanocrystals [12]. In our previous work [11], we have suggested that it is the formation of SiO x shells around nanocrystals that provides relaxation of stresses and photoluminescence in the Si nanocrystals ion synthesized in the initially amorphous Al 2 O 3 films.…”

Section: Introductionmentioning

confidence: 99%

Peculiarities of the formation and properties of light-emitting structures based on ion-synthesized silicon nanocrystals in SiO2 and Al2O3 matrices

et al. 2012

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A comprehensive comparative study of SiO 2 and Al 2 O 3 oxide layers with Si nanocrystals formed by Si + ion implantation and high temperature annealing has been performed. Information on morphology, phase composition, structure, and luminescent properties of ensembles of ion synthesized silicon nanocrys tals has been obtained using confocal Raman microscopy, X ray diffraction, Fourier transform infrared spec troscopy, electron paramagnetic resonance, and photoluminescence. It has been found that the peculiarities of the formation of nanocrystals, the distribution of nanocrystals over the depth of the implanted layer, the structure, and the character of chemical bonds are similar for both types of oxide matrices; however, the pho toluminescence in the wavelength range 600-1000 nm, which is caused by the nanocrystals in the Al 2 O 3 matrix, has been observed only in the case of the formation of SiO 2 shells around the Si nanocrystals. The surface oxidation of the Si nanocrystals, which is necessary for the formation of SiO 2 shells, is possible due to the presence of excess oxygen in the Al 2 O 3 matrix (the case of Si implantation into the deposited Al 2 O 3 film), as well as due to the inflow of oxygen from the annealing atmosphere (the case of Si implantation into sap phire). In order to verify the quantum confinement mechanism of luminescence, available data on the tem perature dependence of the photoluminescence intensity have been analyzed. An analysis of the mechanisms of charge transfer and electroluminescence excitation in diode structures based on thin ion synthesized layers with silicon nanocrystals has also been performed.

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Nanocrystal and interface defects related photoluminescence in silicon-rich Al2O3 films

Cited by 33 publications

References 29 publications

Enhanced photocatalytic hydrogen generation from barium tantalate composites

Enhanced photocatalytic hydrogen generation from barium tantalate composites

Si-rich Al2O3 films grown by RF magnetron sputtering: structural and photoluminescence properties versus annealing treatment

Peculiarities of the formation and properties of light-emitting structures based on ion-synthesized silicon nanocrystals in SiO2 and Al2O3 matrices

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