The role of the recombination centers on the modulated photocurrent: Determination of the gap state parameters of semiconductors

Pomoni, Maria; Giannopoulou, A.; Kounavis, P.

doi:10.1080/14786435.2010.489031

Cited by 6 publications

(14 citation statements)

References 48 publications

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“…[26] and arises from the interaction of electrons with the probed gap states through the trapping-detrapping process, which is demonstrated schematically with the down and up arrows in Figure 1 and is expressed by…”

Section: The Basic Concepts Of the Mpc Analysismentioning

confidence: 99%

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Determination of trapping–detrapping events, recombination processes and gap-state parameters by modulated photocurrent measurements on amorphous silicon

Pomoni

Kounavis

2014

Philosophical Magazine

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Analysis of the out-of-phase modulated photocurrent (MPC) signal, the so-called Y signal, is proposed for determining the trapping-detrapping events, recombination processes and gap-state parameters in amorphous silicon. This is demonstrated by analysing experimental Y spectra obtained on this material from different laboratories including our own. Model simulations are also employed in which the amphoteric nature of the dangling bonds and their distribution according to the defect-pool model are taken into account. From the reconstruction of the Y signal, phase shift and MPC amplitude spectra, several contributions resolved from the frequency dependence of the experimental Y spectra are identified. Two electron trappingdetrapping processes are resolved. These are attributed to hydrogen-related positive defects and to transitions involving the D +/0 level of the normal dangling bonds from the defect-pool distribution. At lower frequencies a residual contribution is resolved that is attributed to a term related to recombination through the D +/0 and D 0/− levels. Between 300 and 150 K the above recombination contribution is essentially from the D 0/− and dominates the Y signal at lower frequencies. In this region a characteristic phase lead appears, which is attributed to the existence of safe hole traps in the valence band tail. Around 150 K, trapping-detrapping events in the conduction band tail dominate.

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Section: The Basic Concepts Of the Mpc Analysismentioning

confidence: 99%

“…The exact expression for Y n obtained in our previous analysis without any approximation, for samples with electrodes in the coplanar geometry [26] consists of an electron trapping term and an electron recombination term according to…”

Section: The Basic Concepts Of the Mpc Analysismentioning

confidence: 99%

Determination of trapping–detrapping events, recombination processes and gap-state parameters by modulated photocurrent measurements on amorphous silicon

Pomoni

Kounavis

2014

Philosophical Magazine

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“…(6). 23,39 Instead of this behavior, the Y/l ratio at low x of pentacene films surprisingly increases (see Fig. 3) from the initial Y o /l o value under the weakest bias-light level to systematically higher Y/l values (up arrow) with the successive increase of the bias-light level.…”

Section: B Changes In the Mobilitymentioning

confidence: 83%

“…(6) a decrease of Y by decreasing x and/or increasing x t . 23 According to the above described prediction, the Y/l ratio of Fig. 3 in the LF spectral region (x < x s ) is expected to decrease with increasing the bias-light level, provided that the mobility l is not affected by the bias-light level.…”

Section: B Changes In the Mobilitymentioning

confidence: 93%

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Density and mobility effects of the majority carriers in organic semiconductors under light excitation

Vagenas

Giannopoulou

Kounavis

2015

Journal of Applied Physics

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This study demonstrates that the effect of light excitation on the density and the mobility of the majority carriers can be explored in organic semiconductors by modulated photocurrent spectroscopy. The spectra of phase and amplitude of the modulated photocurrent of pentacene films indicate a significant increase in the density of the photogenerated mobile holes (majority carriers). This increase is accompanied by a comparatively much smaller increase of the steady state photocurrent response which can be reconciled with a decrease in the mobility (μ) of holes. The decrease of μ is supported from an unusual increase of the Y/μ ratio of the out-of-phase modulated photocurrent (Y) signal to the mobility under light excitation. It is proposed that the mobile holes, which are generated from the dissociation of the light-created excitons more likely near the pentacene-substrate interface by electron trapping, populate grain boundaries charging them and producing a downward band bending. As a result, potential energy barriers are build up which limit the transport of holes interacting through trapping-detrapping with deep partially occupied traps in the charged grain boundaries. On the other hand, the transport of holes interacting through trapping-detrapping with empty traps is found unaffected.

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Photoconductivity: Fundamental Concepts

Kasap

2022

Photoconductivity and Photoconductive Materials

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The role of the recombination centers on the modulated photocurrent: Determination of the gap state parameters of semiconductors

Cited by 6 publications

References 48 publications

Determination of trapping–detrapping events, recombination processes and gap-state parameters by modulated photocurrent measurements on amorphous silicon

Determination of trapping–detrapping events, recombination processes and gap-state parameters by modulated photocurrent measurements on amorphous silicon

Density and mobility effects of the majority carriers in organic semiconductors under light excitation

Photoconductivity: Fundamental Concepts

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