Er3+ and Si luminescence of atomic layer deposited Er-doped Al2O3 thin films on Si(100)

Dingemans, G Gijs; Clark, Andrew; Delft, van Ja; Sanden, van de Mcm Richard; Kessels, Wmm Erwin

doi:10.1063/1.3595691

Cited by 25 publications

(11 citation statements)

References 52 publications

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“…The quantitative Fe concentration within the surface region, from SIMS measurements, corresponds to a bulk Fe concentration of 1.5 × 10 14 cm −3 for a 180‐μm thick silicon wafer. This agrees reasonably well with the implanted Fe concentration of 10 14 cm −3 , considering that the Al 2 O 3 used in SIMS calibration standards may exhibit a different ion yield, and the 900 °C anneals could also potentially change the crystal structure of the Al 2 O 3 films . The Fe peaks at the Al 2 O 3 /Si interfaces, for the two 900 °C 15‐min annealed samples with and without a prior activation step, therefore clearly come from the relocation of Fe from the silicon wafer bulk to the Al 2 O 3 /Si interfaces, as was previously found for Al 2 O 3 gettering at 425 °C .…”

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confidence: 88%

Impurity Gettering by Atomic‐Layer‐Deposited Aluminium Oxide Films on Silicon at Contact Firing Temperatures

Liu

Macdonald

2017

Physica Rapid Research Ltrs

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Aluminium oxide (Al 2 O 3 ) thin films deposited on silicon surfaces, synthesised by plasma-assisted atomic layer deposition, are recently reported to possess impurity gettering effects for the silicon wafer bulk during annealing at 425 C, a typical temperature used for activating the surface passivation quality of the Al 2 O 3 films. This paper investigates the gettering effects of Al 2 O 3 films at higher temperatures of 700-900 C, which are commonly used for contact firing in silicon solar cell fabrication. Iron is used as a marker impurity in silicon to study the gettering effectiveness. Results show that Al 2 O 3 films also generate strong impurity gettering effects at 700-900 C, through a segregation gettering mechanism. The as-deposited Al 2 O 3 films are found to be more effective at gettering than the 425 C-activated Al 2 O 3 films, demonstrating gettering processes that are largely limited by the impurity diffusivity in silicon. For both as-deposited and activated Al 2 O 3 films, gettering during high temperature annealing occurs by impurity accumulation at the Al 2 O 3 /Si interfaces, similar to the gettering action at 425 C. However, some iron is found to redistribute into the bulk of the Al 2 O 3 films after long annealing at a high temperature.

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confidence: 88%

Impurity Gettering by Atomic‐Layer‐Deposited Aluminium Oxide Films on Silicon at Contact Firing Temperatures

Liu

Macdonald

2017

Physica Rapid Research Ltrs

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“…Thus, effective passivation layers are essential for high effi ciency solar cells especially if nanostructured surfaces shall be incorporated. [ 93 ] In the experimental part of the this study, we use ALD-deposited AL 2 O 3 as benchmark (see Experimental Section). [ 68 ] Since 2006 passivation by ALD deposited Al 2 O 3 [ 85,86 ] has been studied extensively for its outstanding performance on (highly doped p-type) [ 87 ] Si.…”

Section: Surface Passivation Technologies Of Black Siliconmentioning

confidence: 99%

Black Silicon Photovoltaics

Otto

Algasinger

Branz

et al. 2014

Advanced Optical Materials

185

117

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LT) can be achieved for weakly absorbed photons with energies close to the absorption edge of silicon. [ 15 ] These properties of b-Si are particularly useful for photovoltaic applications.The limiting effi ciency of a solar cell is given by the detailed balance of absorption and radiative recombination [ 16 ] and by nonradiative processes like Auger-and impurity recombination. [17][18][19] b-Si can help to approach those limits in two ways. On the one hand b-Si improves the coupling of light into the solar cell and the absorption of near band edge photons. This in turn increases the short circuit current and on a logarithmic scale also the open circuit voltage. On the other hand, due to excellent light-trapping properties b-Si might also allow reducing the solar cell thickness substantially below 100 µm while sustaining a high light absorption. This reduces nonradiative bulk recombination losses that scale linearly with the solar cell thickness [ 17,18 ] and hence, increases the open-circuit voltage. Of course, reducing the solar cell thickness also increases the cost effi ciency. Decreasing the amount of required silicon feedstock is a major industry concern as can be seen by the growing interest in kerf-free crystalline silicon solar cell technologies. [20][21][22] Unfortunately, besides bulk effects, surface recombination imposes a very critical limit to the solar This article presents an overview of the fabrication methods of black silicon, their resulting morphologies, and a quantitative comparison of their optoelectronic properties. To perform this quantitative comparison, different groups working on black silicon solar cells have cooperated for this study. The optical absorption and the minority carrier lifetime are used as benchmark parameters. The differences in the fabrication processes plasma etching, chemical etching, or laser processing are discussed and compared with numerical models. Guidelines to optimize the relevant physical parameters, such as the correlation length, optimal height of the nanostructures, and the surface defect densities for optoelectronic applications are given.

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“…7). X-ray diffraction measurements revealed that the Al 2 O 3 films crystallize at temperatures between 850 and 900 C, 46 which is in the range of maximum CO 2 effusion. It is likely that the effusion of carbon impurities coincided with the crystallization of the film.…”

Section: Effect Of Al 2 O 3 Microstructure On Gas Effusionmentioning

confidence: 99%

Influence of annealing and Al2O3 properties on the hydrogen-induced passivation of the Si/SiO2 interface

Dingemans¹,

Einsele²,

Beyer³

et al. 2012

Journal of Applied Physics

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144

131

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Annealing at moderate temperatures is required to activate the silicon surface passivation by Al2O3 thin films while also the thermal stability at higher temperatures is important when Al2O3 is implemented in solar cells with screenprinted metallization. In this paper, the relationship between the microstructure of the Al2O3 film, hydrogen diffusion, and defect passivation is explored in detail for a wide range of annealing temperatures. The chemical passivation was studied using stacks of thermally-grown SiO2 and Al2O3 synthesized by atomic layer deposition. Thermal effusion measurements of hydrogen and implanted He and Ne atoms were used to elucidate the role of hydrogen during annealing. We show that the passivation properties were strongly dependent on the annealing temperature and time and were significantly influenced by the Al2O3 microstructure. The latter was tailored by variation of the deposition temperature (Tdep = 50 °C–400 °C) with hydrogen concentration [H] between 1 and 13 at.% and mass density ρmass between 2.7 and 3.2 g/cm3. In contrast to films with intermediate material properties, the passivation by low- and high density films showed a reduced thermal stability at relatively high annealing temperatures (∼600 °C). These observations proved to be in good agreement with thermal effusion results of hydrogen and inert gas atoms that were also strongly dependent on film microstructure. We demonstrate that the temperature of maximum effusion decreased for films with progressively lower density (i.e., with increasing [H]). Therefore, the reduced thermal stability of the passivation for low-density hydrogen-rich ([H] >∼5 at. %) films can be attributed to a loss of hydrogen at relatively low annealing temperatures. In contrast, the lower initial [H] for dense Al2O3 films can likely explain the lower thermal stability associated with these films. The effusion measurements also allowed us to discuss the role of molecular- and atomic hydrogen during annealing.

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Er3+ and Si luminescence of atomic layer deposited Er-doped Al2O3 thin films on Si(100)

Cited by 25 publications

References 52 publications

Impurity Gettering by Atomic‐Layer‐Deposited Aluminium Oxide Films on Silicon at Contact Firing Temperatures

Impurity Gettering by Atomic‐Layer‐Deposited Aluminium Oxide Films on Silicon at Contact Firing Temperatures

Black Silicon Photovoltaics

Influence of annealing and Al2O3 properties on the hydrogen-induced passivation of the Si/SiO2 interface

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