Effective optimization of surface passivation on porous silicon carbide using atomic layer deposited Al<sub>2</sub>O<sub>3</sub>

Lu, Weifang; Iwasa, Yoshimi; Ou, Yiyu; Jinno, Daiki; Kamiyama, Satoshi; Petersen, Paul Michael; Ou, Haiyan

doi:10.1039/c6ra27281a

Cited by 59 publications

(54 citation statements)

References 26 publications

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“…To achieve ohmic contacts on the backside of SiC samples, layered nickel (100 nm)/titanium (10 nm)/gold (200 nm) films were prepared by sputtering or e-beam evaporation processes. An anodic etching process was executed to form the porous layers on the SiC substrate as described in our previous publication 26 . The samples were immersed in a 5% HF solution and exposed under the UV irradiation of 365 nm by using mercury lamp.…”

Section: Resultsmentioning

confidence: 99%

“…Herein, we proposed an innovative method to achieve white light emission by converting NUV light in a hybrid structure composed of N-B co-doped 6H-SiC and porous layer formed on top of it. The porous SiC layer can emit broadband blue-green light which is attributed to the surface defects related emission 22 – 24 and the luminescence intensity is rather stable after passivation by atomic layer deposited (ALD) dielectric films 25 , 26 . By combining the blue-green emission from the porous layer and the yellow emission from the fluorescent SiC substrate, the emitting spectrum can cover the whole visible range.…”

Section: Introductionmentioning

confidence: 99%

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White Light Emission from Fluorescent SiC with Porous Surface

Fiordaliso

et al. 2017

Sci Rep

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AbstarctWe report for the first time a NUV light to white light conversion in a N-B co-doped 6H-SiC (fluorescent SiC) layer containing a hybrid structure. The surface of fluorescent SiC sample contains porous structures fabricated by anodic oxidation method. After passivation by 20 nm thick Al2O3, the photoluminescence intensity from the porous layer was significant enhanced by a factor of more than 12. Using a porous layer of moderate thickness (~10 µm), high-quality white light emission was realized by combining the independent emissions of blue-green emission from the porous layer and yellow emission from the bulk fluorescent SiC layer. A high color rendering index of 81.1 has been achieved. Photoluminescence spectra in porous layers fabricated in both commercial n-type and lab grown N-B co-doped 6H-SiC show two emission peaks centered approximately at 460 nm and 530 nm. Such blue-green emission phenomenon can be attributed to neutral oxygen vacancies and interface C-related surface defects generated dring anodic oxidation process. Porous fluorescent SiC can offer a great flexibility in color rendering by changing the thickness of porous layer and bulk fluorescent layer. Such a novel approach opens a new perspective for the development of high performance and rare-earth element free white light emitting materials.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

White Light Emission from Fluorescent SiC with Porous Surface

Fiordaliso

et al. 2017

Sci Rep

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“…Broad emission is typical of Cu-poor CIGS polycrystalline solar cells, [59][60][61] however, for the case of the reference solar cell, the luminescence is significantly broader than that of the passivated cell. [64][65][66][67][68] However, a direct comparison of PL intensity from different samples should be done with caution due to the necessarily different optical alignments despite nominally equivalent experimental conditions and as in this work we do not have those capabilities and we do not perform that comparison here. [62,63] Regarding the passivated solar cell, the full width at half maximum (FWHM) is significantly lower (≈61 meV) than that of the reference solar cell (≈96 meV).…”

Section: Photoluminescencementioning

confidence: 99%

Passivation of Interfaces in Thin Film Solar Cells: Understanding the Effects of a Nanostructured Rear Point Contact Layer

Salomé

Vermang

Ribeiro‐Andrade

et al. 2017

Adv Materials Inter

110

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Thin film solar cells based in Cu(In,Ga)Se2 (CIGS) are among the most efficient polycrystalline solar cells, surpassing CdTe and even polycrystalline silicon solar cells. For further developments, the CIGS technology has to start incorporating different solar cell architectures and strategies that allow for very low interface recombination. In this work, ultrathin 350 nm CIGS solar cells with a rear interface passivation strategy are studied and characterized. The rear passivation is achieved using an Al2O3 nanopatterned point structure. Using the cell results, photoluminescence measurements, and detailed optical simulations based on the experimental results, it is shown that by including the nanopatterned point contact structure, the interface defect concentration lowers, which ultimately leads to an increase of solar cell electrical performance mostly by increase of the open circuit voltage. Gains to the short circuit current are distributed between an increased rear optical reflection and also due to electrical effects. The approach of mixing several techniques allows us to make a discussion considering the different passivation gains, which has not been done in detail in previous works. A solar cell with a nanopatterned rear contact and a 350 nm thick CIGS absorber provides an average power conversion efficiency close to 10%.

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“…This phenomenon was more significant in the catalysts containing Ce. The Al 2p spectrum of the catalysts before PSR contains peaks corresponding to Al-O and Al-O-H at 74.2 and 76.8 eV, respectively [44]. After the reaction, the only Al peak in the lattice was observed at 74.1 eV.…”

Section: Propane Steam Reforming Reaction Over 30co X Ce Y /70γ-al 2 mentioning

confidence: 98%

“…However, the migration was not significant for 30Co 0.85 Ce 0.15 /70γ-Al 2 O 3 . This is because Co can continue to be supplied with oxygen by the cerium oxide [44], and it would not have been perfectly reduced into Co metal after the PSR reaction. Eventually, the oxygen supply of Ce prevents sintering between the reduced Co metal particles, which slows the deterioration of the catalyst.…”

Section: Propane Steam Reforming Reaction Over 30co X Ce Y /70γ-al 2 mentioning

confidence: 99%

Effect of Ce Doping of a Co/Al2O3 Catalyst on Hydrogen Production via Propane Steam Reforming

et al. 2018

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We synthesized cerium-doped cobalt-alumina (CoxCey/Al2O3) catalysts for the propane steam reforming (PSR) reaction. Adding cerium introduces oxygen vacancies, and the oxygen transfer capacity of the Ce promoter favors CO to CO2 conversion during PSR, inhibiting coke deposition and promoting hydrogen production. The best PSR activity was achieved at 700 °C using the Co0.85Ce0.15/Al2O3 catalyst, which showed 100% propane (C3H8) conversion and about 75% H2 selectivity, and 6% CO, 5% CO2, and 4% CH4 were obtained. In contrast, the H2 selectivity of the base catalyst, Co/Al2O3, is 64%. The origin of the difference in activity was the lower C3H8 gas desorption temperature of the Co0.85Ce0.15/Al2O3 catalyst compared to that of the Co/Al2O3 catalyst; thus, the PSR occurred at low temperatures. Furthermore, more CO was adsorbed on the Co0.85Ce0.15/Al2O3 catalyst, and subsequently, desorbed as CO2. The activation energy for water desorption from the Co0.85Ce0.15/Al2O3 catalyst was 266.96 kJ/mol, higher than that from Co/Al2O3. Furthermore, the water introduced during the reaction probably reacted with CO on the Co0.85Ce0.15/Al2O3 catalyst, increasing CO2 generation. Finally, we propose a mechanism involving the Co0.85Ce0.15/Al2O3 catalyst, wherein propane is reformed on CoxCey sites, forming H2, and CO, followed by the conversion of CO to CO2 by water on CeO2 sites.

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Effective optimization of surface passivation on porous silicon carbide using atomic layer deposited Al₂O₃

Abstract: Significant enhancement of photoluminescence in ALD Al2O3 passivated porous 6H-SiC.

Cited by 59 publications

References 26 publications

White Light Emission from Fluorescent SiC with Porous Surface

White Light Emission from Fluorescent SiC with Porous Surface

Passivation of Interfaces in Thin Film Solar Cells: Understanding the Effects of a Nanostructured Rear Point Contact Layer

Effect of Ce Doping of a Co/Al2O3 Catalyst on Hydrogen Production via Propane Steam Reforming

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Effective optimization of surface passivation on porous silicon carbide using atomic layer deposited Al2O3

Abstract: Significant enhancement of photoluminescence in ALD Al2O3 passivated porous 6H-SiC.

Cited by 59 publications

References 26 publications

White Light Emission from Fluorescent SiC with Porous Surface

White Light Emission from Fluorescent SiC with Porous Surface

Passivation of Interfaces in Thin Film Solar Cells: Understanding the Effects of a Nanostructured Rear Point Contact Layer

Effect of Ce Doping of a Co/Al2O3 Catalyst on Hydrogen Production via Propane Steam Reforming

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Effective optimization of surface passivation on porous silicon carbide using atomic layer deposited Al₂O₃