Determination of gap-state distributions in amorphous semiconductors from transient photocurrents using a fourier transform technique

Main, C.; Brüggemann, R.; Webb, D.P.; Reynolds, S.

doi:10.1016/0038-1098(92)90076-l

Cited by 70 publications

(27 citation statements)

References 10 publications

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“…This is a quite reasonable assertion, as we will demonstrate. We have shown in earlier work [15,16] that it is possible, using a Fourier transform technique, to deconvolute TPC data in a model-independent way, to compute the DOS profile. Figure 8 shows the DOS obtained in this way for the silicon carbide film under investigation.…”

Section: Resultsmentioning

confidence: 99%

Decay from steady‐state photocurrent in amorphous semiconductors

Main

Reynolds

Brüggemann

2004

phys. stat. sol. (c)

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This paper presents analysis, computer modeling and experimental measurements of the photoconductive decay which occurs on cessation of illumination, in amorphous semiconductors. We explore the processes of relaxation of the excess carrier distributions using a capture-rate analysis, and examine the relative roles of re-trapping and recombination in exemplar cases of exponential trapping state profiles, with monomolecular and bimolecular recombination. We classify decay under strong or weak retrapping conditions which can be selected for by the prior steady generation rate, and this results in a rich variety of possible decay behavior. We examine several plausible intuitive explanations of the decay process, and show in detail that these explanations fail to predict accurately the speed and generation rate dependence of the decay. Results of experimental measurements of the decay from steady state and the impulse response in films of a-Si 1-x C x :H are presented.

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Section: Resultsmentioning

confidence: 99%

Decay from steady‐state photocurrent in amorphous semiconductors

Main

Reynolds

Brüggemann

2004

phys. stat. sol. (c)

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“…Floating bonds, or overcoordinated Si atoms, showed the second largest correlation in our ensembles, while DBs contributed little to the band-tail trap states. Additional works have experimentally measured hole mobilities in deposited films over ranges of deposition conditions [14][15][16], and modeled the densities of band-tail states implied from these measurements [17][18][19][20][21]. Studies have also sought to measure densities of coordination defects experimentally, namely through electron paramagnetic resonance (EPR), although recent work has shown that such results are challenging to interpret because of the importance of the surrounding geometry on the measurement of the coordination defect [22].…”

Section: Introductionmentioning

confidence: 99%

Hole-mobility-limiting atomic structures in hydrogenated amorphous silicon

et al. 2014

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Low hole mobility currently limits the efficiency of amorphous silicon photovoltaic devices. We explore three possible phenomena contributing to this low mobility: coordination defects, self-trapping ionization displacement defects, and lattice expansion allowing for hole wave-function delocalization. Through a confluence of experimental and first-principles investigations, we demonstrate the fluidity of the relative prevalence of these defects as film stress and hydrogen content are modified, and that the mobility of a film is governed by an interplay between various defect types.

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“…Simplified analytical expressions could be derived, which allow to reconstruct the DOS from frequency, temperature or optical bias spectroscopies [16,[33][34][35][36][37][38], and introduce the concept of frequency dependent trap-limited mobility [33,[39][40][41]. It has also been shown that modulated and transient photocurrents are intimately related, the latter being a signature in the time domain, while the former works in the frequency domain [42][43][44]. In the present paper, we give a short overview of the MPC technique, where the different regimes and different ways of analysing the data are described.…”

Section: Introductionmentioning

confidence: 99%

The modulated photocurrent technique: a powerful tool to investigate band gap states in silicon based thin films

Kleider

Longeaud

Gueunier

2004

phys. stat. sol. (c)

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The Modulated PhotoCurrent (MPC) technique is a very simple experiment that provides insight into localized gap states in semiconductors. It is particularly well suited to disordered silicon based thin films. We here give a review of the technique, emphasizing the effect of experimental parameters (frequency, temperature, dc generation rate) and the reconstruction of the density of states (DOS) in the two regimes: the widely used high frequency regime and the recently developed low frequency regime. We discuss the effect of different trap species and propose a new way to determine capture cross sections from the matching of the reconstructed DOS in both regimes. Illustrations are given theoretically with the help of a numerical modelling, and experimentally from data obtained on polymorphous silicon-germanium alloys.

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Determination of gap-state distributions in amorphous semiconductors from transient photocurrents using a fourier transform technique

Cited by 70 publications

References 10 publications

Decay from steady‐state photocurrent in amorphous semiconductors

Decay from steady‐state photocurrent in amorphous semiconductors

Hole-mobility-limiting atomic structures in hydrogenated amorphous silicon

The modulated photocurrent technique: a powerful tool to investigate band gap states in silicon based thin films

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