Recombination in semiconductor electrodes: Investigation by the electrical and optoelectrical impedance method

Vanmaekelbergh, D.; Wit, A.R. de; Cardon, F.

doi:10.1063/1.353776

Cited by 28 publications

(18 citation statements)

References 32 publications

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“…This value was confirmed by intensity modulated photocurrent spectroscopy [21]. We note that k n is about four orders of magnitude smaller than the value reported for n-GaAs, illustrating that recombination is much slower at silicon surfaces [22].…”

Section: In Situ Measurements Of Interface States At Silicon Surfacessupporting

confidence: 73%

In SituMeasurements of Interface States at Silicon Surfaces in Fluoride Solutions

1996

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The energetics and kinetics of processes involving interface states at silicon (111) surfaces in aqueous fluoride solutions were determined using in situ impedance spectroscopy. In the dark, we observe electrically active surface states with densities in the range 2 3 10 10 to 1 3 10 12 cm 22 dependent on the surface chemistry. The surface states are physically the same, independent of pH, with a capture cross section of 1 3 10 216 cm 2 . Measurements under illumination show that recombination occurs at different interface states than those observed in the dark.

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Section: In Situ Measurements Of Interface States At Silicon Surfacessupporting

confidence: 73%

In SituMeasurements of Interface States at Silicon Surfaces in Fluoride Solutions

1996

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“…This shows that light modulated techniques can provide only as much information as IS. This conclusion was previously remarked by Vanmaekelbergh et al for recombination in semiconductor electrodes . One should however notice that each process will be detected at different frequencies, depending on the nature of the technique.…”

supporting

confidence: 68%

“…The state of the system will then be represented by a more general function Λ ω that reduces to eq when ω = 0 (the steady-state limit of operation). From the standpoint of modeling, Λ ω is obtained by a set of drift–diffusion equations involving small perturbation of carrier densities that can be solved in terms of ( ĵ e , V̂ , ĵ Φ ) . The use of a small perturbation ensures a linear response so that, in contrast to eq , the modulated variables (denoted by a circumflex) obey a linear relationship …”

mentioning

confidence: 99%

Investigating the Consistency of Models for Water Splitting Systems by Light and Voltage Modulated Techniques

Bertoluzzi

Bisquert

2016

J. Phys. Chem. Lett.

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The large diffusion lengths recurrently measured in perovskite single crystals and films signals small bulk nonradiative recombination flux and locate the dominant carrier recombination processes at the outer interfaces. Surface recombination largely determines the photovoltaic performance, governing reductions in short circuit current and open circuit voltage. Quantification of recombination losses is necessary to reach full understanding of the solar cell operating principles. Complete impedance model is given which connects capacitive and resistive processes to the electronic kinetics at the interfaces. Carrier collection losses affecting the photocurrent have been determined to equal 1%. Photovoltage loss is linked to the decrease in surface hole density, producing 0.3 V-reduction with respect to the ideal radiative limit. Our approach enables a comparison among different structures, morphologies and processing strategies of passivation and buffer layers. TOC figure

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“…Since the modelling already assumes that no holes are captured outside the SCR, we conclude that electron-hole recombination is likely to be occurring inside the SCR, even under conditions where holes are consumed rapidly by a hole scavenger like H 2 O 2 when they arrive at the interface. The theory of IMPS for recombination in the SCR has been discussed by Vanmaekelbergh and deWit [36], but since it appears that surface recombination is normally dominant in semiconductor electrodes, the theory appears never to have been used to interpret IMPS data. These authors performed numerical calculations for a typical parameter values and found that the relaxation time constant was around 50 microseconds.…”

Section: Comparison Of the Eqe Model With Experiments In The Case Of Hmentioning

confidence: 99%

Understanding the role of nanostructuring in photoelectrode performance for light-driven water splitting

Peter

Gurudayal

Wong

et al. 2018

Journal of Electroanalytical Chemistry

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The analysis of capacitance data for regular nanostructured photoelectrodes is revisited using a hematite nanorod array as an example. The effects of the cylindrical nanorod geometry on the capacitance-voltage behaviour are outlined, and the limiting case of complete depletion is discussed in terms of the residual geometric capacity at the base of the nanorods. Since nanorod arrays generally leave areas of the substrate exposed, it is necessary to consider the parallel capacitance associated with the fraction of uncovered surface. The sensitivity of the capacitance fitting to parameter variation is explored. The enhancement of external quantum efficiency (EQE) by nanostructuring is also discussed using hematite nanorod arrays as experimental examples. It is shown that, although very substantial EQE enhancement should be achieved by simple geometric effects, the performance of nanostructured hematite electrodes in the visible region of the spectrum is considerably lower than predicted if all charge carriers generated in the space charge region (SCR) were collected. Further analysis reveals that the internal quantum efficiency increases with photon energy, suggesting that the probability of generating free, rather than bound, electron-hole pairs in hematite depends on the excess energy h-E gap .

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Recombination in semiconductor electrodes: Investigation by the electrical and optoelectrical impedance method

Cited by 28 publications

References 32 publications

In SituMeasurements of Interface States at Silicon Surfaces in Fluoride Solutions

In SituMeasurements of Interface States at Silicon Surfaces in Fluoride Solutions

Investigating the Consistency of Models for Water Splitting Systems by Light and Voltage Modulated Techniques

Understanding the role of nanostructuring in photoelectrode performance for light-driven water splitting

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