Generation and Quenching of Luminescence in n-Type Porous Silicon/Solution Diodes:  Role of Adsorbed Hydrogen

Kelly, J. J.; Kooij, Ernst S.; Vanmaekelbergh, Daniël

doi:10.1021/la981435r

Cited by 12 publications

(7 citation statements)

References 41 publications

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“…The quenching of por-Si PL by various solvents and adsorbates is well known. [58][59][60][61][62][63][64][65][66][67][68] When the pores are filled with a higher dielectric constant medium ͑such as ethanol vs air͒, a blue shift in the PL is expected. 37,69 We observed evidence for both of these phenomena for stain-etched por-Si exposed to ethanol.…”

Section: Solutionmentioning

confidence: 99%

Effects of Stain Etchant Composition on the Photoluminescence and Morphology of Porous Silicon

Nahidi

Kołasiński

2006

J. Electrochem. Soc.

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Stain etching of silicon provides a spontaneous, self-limiting chemical method to produce nanocrystalline silicon films ͑porous Si͒. Whereas the existence of etchants capable of producing porous Si has been known for some time, little has been known concerning how solution composition influences the efficacy of porous Si production and the properties of the resulting films. We demonstrate that the fluoride species may be derived from either HF or acidified NH 4 HF 2 . A range of oxidants may be used as long as their counterions do not lead to precipitation. However, a large positive electrochemical potential is not a sufficient condition for efficient porous Si production. Bubble production, which is deleterious to film homogeneity and long thought to be inherent to the process, can be avoided by the use of transition metal-containing oxidants. Properties of the film, such as morphology, growth rate, porosity, and the wavelength of the photoluminescence maximum, respond to the etchant composition. We observe a blue shift in photoluminescence, which correlates with an increasingly positive electrochemical potential ͑E 0 ͒ of the oxidant. It is argued that E 0 plays a role much like wavelength in photoelectrochemical etching and that smaller nanocrystals are produced with more positive values of E 0 .

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Section: Solutionmentioning

confidence: 99%

Effects of Stain Etchant Composition on the Photoluminescence and Morphology of Porous Silicon

Nahidi

Kołasiński

2006

J. Electrochem. Soc.

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“…45 The possible reactions are given below: This is attributable to generation of hydroxyl radicals owing to thermodynamically favoured reduction of H 2 O 2 by the conduction band electrons as the E CB of CuO is less than the E H of H 2 O 2 /cOH (which is given as 0.87 eV in the NHE).…”

Section: Mechanism Of Photocatalytic Degradationmentioning

confidence: 99%

“…In the case of spiking with potassium persuphate, the highly reactive SO 4 c À species are formed due to reduction of S 45 Overall, the sulphate radical (SO 4 c À ) interacts with water in the reaction medium to produce highly oxidative hydroxyl radical as shown below: 47…”

Section: Photocatalytic Dye Degradationmentioning

confidence: 99%

Studies on the drastic improvement of photocatalytic degradation of acid orange-74 dye by TPPO capped CuO nanoparticles in tandem with suitable electron capturing agents

Sharma

Dutta

2015

RSC Adv.

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Highly stable copper oxide (CuO) nanoparticles are synthesized by a precipitation method and stabilized by in situ capping with triphenylphosphine oxide (TPPO). The as-synthesized CuO nanoparticles were characterized for average particle size (8 nm) by transmission electron micrography (TEM); an optical band gap of 2.29 eV by diffused reflectance spectroscopy and a large BET surface area (105.82 m 2 g À1 ).The sunlight induced photocatalytic activity towards the degradation of acid orange 74 (an azo dye) by TPPO capped CuO nanoparticles was attributed to unfavorable electron capturing by molecular oxygen to produce reactive oxygen species. This is demonstrated from theoretical band structure calculations which revealed valence band edge (2.59 eV) and conduction band edge (0.29 eV) for TPPO capped CuO nanoparticles, which are unfavourable for electron transfer with respect to the redox potentials of O 2 / O 2 c À (À0.2 eV) and H 2 O/cOH (2.2 eV) in the NHE scale. Strikingly, TPPO capped CuO nanoparticles when mixed with 5 mM K 2 S 2 O 8 exhibited 99% degradation of acid orange-74 in 180 min under sunlight exposure. A similar dye degradation efficiency was observed when CuO nanoparticles were mixed with H 2 O 2 in the reaction medium. The mechanism for the drastic improvement in the dye degradation due to the addition of K 2 S 2 O 8 or H 2 O 2 has been explained on the basis of favorable redox couples of S 2 O 8 2À /SO 4 c À (2.01 eV) and H 2 O 2 /cOH (0.87 eV) which could accept photoexcited electrons from the conduction band of CuO to produce reactive hydroxyl radical species. Using selective scavenger for reactive oxygen species, the generation of O 2 c À was ruled out and hydroxyl radicals were confirmed as the major reactive oxygen species for the degradation of acid orange-74 dye. Ion chromatography studies of the aliquot left after sunlight induced photocatalytic dye degradation revealed anions, viz.nitrate, sulphate, oxalate and formate, which are released due to mineralization of the dye solution by a photocatalytic process. The performance of the photocatalytic dye degradation was unchanged for 5 repetitive catalytic cycles and hence it was concluded that TPPO capped CuO nanoparticles offer excellent photocatalytic dye degradation ability when suitable electron capturing agents like potassium persulphate are used in tandem.

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“…Она предложена из на-блюдения значительного уменьшения интен-сивности ФЛ р-Si после термической десорб-ции Н 2 от ПК и возможности восстановления ФЛ путем кратковременной обработки с по-мощью HF, восстанавливающей слой Н 2 на поверхности [30]. При объяснении выдвинуто-го предположения исходят из того, что при де-сорбции Н 2 получаются оборванные связи Si, которые могут выступать как безлучеиспуска-тельные центры [62,83,84].…”

Section: фл в красной области спектраunclassified

Biosensors Based on the Photoluminescence of Porous Silicon. Overall Characteristics and Application

Стародуб¹,

Starodub²

2014

SEMST

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Generation and Quenching of Luminescence in n-Type Porous Silicon/Solution Diodes: Role of Adsorbed Hydrogen

Cited by 12 publications

References 41 publications

Effects of Stain Etchant Composition on the Photoluminescence and Morphology of Porous Silicon

Effects of Stain Etchant Composition on the Photoluminescence and Morphology of Porous Silicon

Studies on the drastic improvement of photocatalytic degradation of acid orange-74 dye by TPPO capped CuO nanoparticles in tandem with suitable electron capturing agents

Biosensors Based on the Photoluminescence of Porous Silicon. Overall Characteristics and Application

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