Generalized theory for analytical simulation of the steady-state photocarrier grating technique

Abel, C.-D.; Bauer, G.H.; Bloss, W. H.

doi:10.1080/13642819508239105

Cited by 15 publications

(16 citation statements)

References 13 publications

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“…In order to fit the field dependence experimental data of/?, using Abel et al approach [4], the value of (fit) p extracted from the low field fit and (fit)" taken from the experimental data are employed as input data, in a FORTRAN computer program [8]. Thus, only one adjustable parameter is used to fit the experimental data, here, namely, faT® and y is given a value 0.61.…”

Section: Results Due To Application Of Abel Et Al Approachmentioning

confidence: 99%

“…The change in the external field from low values to high values results consequently in a change from diffusion-dominated to drift-dominated transport process. Several theoretical studies based on small signal approximations were used to show the effect of varying electric field on p [4][5][6][7][8][9]. This paper concentrates on the investigation of the field dependence of the coefficient /?…”

Section: Introductionmentioning

confidence: 99%

“…The detection of photocarrier grating amplitude, in a steady-state photocarrier grating technique (SSPG), is a good probe for determining the diffusion length [1][2][3][4][5][6][7][8][9]. The measurement of small signal conductivity in SSPG depends on the grating period A which, in turn, varies as the angle of incidence of two laser beams of different intensities.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Estimations of Carrier Mobility and Trapped-Carrier Density of States for Microcrystalline Silicon Semiconductors from Analysis of Field Dependent Steady-State Photocarrier Grating Measurements

Badran¹

2007

AIP Conference Proceedings

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Section: Results Due To Application Of Abel Et Al Approachmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Estimations of Carrier Mobility and Trapped-Carrier Density of States for Microcrystalline Silicon Semiconductors from Analysis of Field Dependent Steady-State Photocarrier Grating Measurements

Badran¹

2007

AIP Conference Proceedings

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“…A novel aspect was introduced by Abel and Bauer [15] who numerically solved the transport and Poisson equations and compared the solutions with a generalized theory which enables to study the SSPG results by the variation of L and/or electric field E. These authors derive their expressions in terms of the mobility-lifetime product ðmtÞ min of the minority carriers, which can be determined from the SSPG method and related to L.…”

Section: Introductionmentioning

confidence: 99%

Steady‐State Photocarrier Grating Method

Brüggemann

2011

Advanced Characterization Techniques for Thin Film Solar Cells

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The excess-carrier properties of a photoexcited semiconductor are important indicators of its quality with respect to applications in optoelectronic devices or for studying the recombination physics. In contrast to the majority-carrier properties, which can be determined rather straightforwardly by stationary photocurrent measurements, the minority-carrier properties can only be revealed by more sophisticated methods. In this respect the steady-state photocarrier grating (SSPG) method has had an enormous impact since it was suggested by Ritter, Zeldov, and Weiser, named RZW hereafter, in 1986 [1].The SSPG method is based on the carrier diffusion under the presence of a spatial sinusoidal modulation in the photogeneration rate G, which induces a so-called photocarrier grating. From photocurrent measurements at different grating periods L, the ambipolar diffusion lengthL can be determined by an analysis that assumes ambipolar transport and charge neutrality.The proposal by RZW, following papers on the analysis [2, 3] and the simple setup triggered a rapid widespread application [4][5][6][7][8]. In parallel, critical and more in-depth accounts on the underlying theory were given to put the technique on a firm ground or to describe its limits when applied to semiconductors with traps. Ritter et al. [9], Balberg et al. [10, 11], Li [12], and Shah et al. [13] analyzed the transport equations, also with respect to the lifetime or relaxation time regimes. In the lifetime regime, the carrier lifetimes are longer than the dielectric relaxation time. The previous publications were later criticized by Hattori et al. [14] who performed a second-order perturbation approach and pointed out deficiencies of other earlier analyses. Nevertheless, Hattori et al. showed that under the conditions in the lifetime regime the analysis and evaluation of the SSPG method are correct. These authors also suggested a correction method to avoid incorrect values of L.A novel aspect was introduced by Abel and Bauer [15] who numerically solved the transport and Poisson equations and compared the solutions with a generalized theory which enables to study the SSPG results by the variation of L and/or electric j177 field E. These authors derive their expressions in terms of the mobility-lifetime product ðmtÞ min of the minority carriers, which can be determined from the SSPG method and related to L.More recently, Schmidt and Longeaud [16] developed a generalized derivation of the solution of the SSPG equations at low E. They identified the shortcomings in the previous derivations which differ from the numerical solution. Their approach also allows the SSPG experiment to be used for the density-of-states (DOS) determination.An important aspect is the above-mentioned association of L with the ðmtÞ min product of the minority carriers. Together with the majority-carrier mobility-lifetime product ðmtÞ maj at the same G from the photoconductivity s ph via s ph ¼ eGðmtÞ maj , where e equals 1.6 Â 10 À19 C, the excess-carrier properties can be related to e...

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“…Several authors addressed the subject of analyzing theoretical aspects of SSPG, 3-6 but a controversy about whether ambipolar transport occurred in amorphous semiconductors remained. In 1995, Abel et al 7 presented a generalized treatment of SSPG, including bipolar transport and the effects of the external electric field. These authors obtained an analytical expression which could be used as a fitting function for experiments where the grating period ⌳ and the electric field were varied.…”

mentioning

confidence: 99%

Density of states determination from steady-state photocarrier grating measurements

Schmidt

Longeaud

2004

Applied Physics Letters

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We present a method to obtain the density of states (DOS) of photoconductive insulators based on steady-state photocarrier grating (SSPG) measurements. A simple expression—relating the DOS at the electron quasi-Fermi level to measurable quantities—is deduced by performing suitable approximations from the analytical solution of the generalized equations that describe the SSPG experiment. The validity of the approximations and the applicability of the final expression are verified from numerical simulations of the process. The usefulness of the method is demonstrated by performing measurements on a standard hydrogenated amorphous silicon sample.

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Generalized theory for analytical simulation of the steady-state photocarrier grating technique

Cited by 15 publications

References 13 publications

Estimations of Carrier Mobility and Trapped-Carrier Density of States for Microcrystalline Silicon Semiconductors from Analysis of Field Dependent Steady-State Photocarrier Grating Measurements

Estimations of Carrier Mobility and Trapped-Carrier Density of States for Microcrystalline Silicon Semiconductors from Analysis of Field Dependent Steady-State Photocarrier Grating Measurements

Steady‐State Photocarrier Grating Method

Density of states determination from steady-state photocarrier grating measurements

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