Optical spectroscopy of the density of gap states in ETP-deposited a-Si:H

Willekens, J; Brinza, Monica; Güngör, Tayyar; Adriaenssens, G.J.; Nesládek, Miloš; Kessels, Wmm Erwin; Smets, Ahm Arno; Sanden, van de Mcm Richard

doi:10.1016/j.jnoncrysol.2004.02.078

Cited by 9 publications

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References 6 publications

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“…A realistic value of the CBT characteristic energy kT c =30 meV is chosen. Concerning the characteristic energy of the VBT kT v , it is taken in the range 45-75 meV [29][30][31][32][33]. The capture cross-sections of states at the centres of the band tails are taken to be constant, independent of energy: s = The respective capture coefficients are given by the product σν th where ν th =10 7 cm s −1 is the thermal velocity [36].…”

Section: Simulation Parametersmentioning

confidence: 99%

Numerical simulation and validity of the surface photovoltage method in amorphous silicon with a Schottky contact

Hammoudi¹,

Tata

Laidoudi

et al. 2018

Semicond. Sci. Technol.

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The steady-state surface photovoltage technique (SPV) is widely used to evaluate minority photocarriers diffusion length for the characterization of photovoltaic device performance. This contact technique shows the difficulty to evaluate the true minority photocarriers diffusion length (L p ) of hydrogenated amorphous silicon (a-Si:H) even though the space charge region is reduced. In this work, we propose a formula to predict more accurately minority diffusion length L p depending on apparent diffusion length (L app ) and space charge width (W). This formula is deduced by Moore's analytical solution in relation to other forms. All transport phenomena taken into account, a complete one-dimensional numerical simulation of the SPV on an Au/a-Si:H Schottky structure is developed. The apparent diffusion length L app and the space charge width W are determined using SPV simulation. The standard density of states (DOS) of the a-Si:H is used. Poisson's equation and the two continuity equations for charge carriers are numerically solved. The SPV assumptions involving W are explored for a set of parameters of the a-Si:H DOS. This numerical simulation shows a linear dependence of L app up on the valence band tail energy, which agrees well with the experimental results. The L p values obtained by the new formula are compared to L app and discussed for a typical DOS parameters of a-Si:H.

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Section: Simulation Parametersmentioning

confidence: 99%

Numerical simulation and validity of the surface photovoltage method in amorphous silicon with a Schottky contact

Hammoudi¹,

Tata

Laidoudi

et al. 2018

Semicond. Sci. Technol.

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Determination of free-carrier and phonon-assisted absorptions for Si-doped GaSb thin layers

et al. 2013

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International audiencePhotothermal deflection spectroscopy is used in order to investigate near- and sub-band gap absorption of Si-doped GaSb epilayers deposited by MBE on a semi-insulating GaAs substrate. The optical absorption spectra show an extra absorption on the transparency region below the bandgap due to free-carrier absorption. However, for energies above the gap, we notice a linear behavior of the square root of the absorption coefficient versus the heating beam energy, which is attributed to phonon-assisted absorption. From interpolation of the phonon absorption to low energies we have determined the free-carrier absorption that is found to follow the Drude law

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