The properties of free carriers in amorphous silicon

Fauchet, P. M.; Hulín, D.; Vanderhaghen, R.; Mourchid, A.; Nighan, W. L.

doi:10.1016/s0022-3093(05)80521-6

Cited by 80 publications

(46 citation statements)

References 25 publications

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“…The values of bimolecular recombination coefficient, evaluated from the photoSCLC measurements are in good agreement with the same values obtained by optical pump-and-probe experiments [6,7]. In comparison with the latter technique, photoSCLC method provides some advantages: the measurements are carried out in the nanosecond time scale although the recombination occurs in the picosecond time scale; also there is a possibility to measure B separately for the electrons and holes, and to distinguish between carrier trapping and recombination processes.…”

supporting

confidence: 83%

Peculiarities of Space-Charge-Limited Photocurrent

et al. 1997

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We demonstrate new advantages of the space-charge-limited photocurrent technique for the investigations of charge carrier recombination. Bimolecular recombination coefficient in a-Si:H estimated according to suggested method for both electrons and holes is presented.PACS numbers: 73.50. Fq, 73.50.Gr, 73.61.JcIn a time-of-flight (TOF) experiment, nonequilibrium carriers are generated by short electrical or optical pulse in thin semi-insulating sample, sandwiched between two electrodes with applied external dc electric field. As a result, transient current occurs, and from its dynamics peculiarities of carrier transport can be studied.The TOF technique can be used in the socalled "small-signal" regime, for which the charge of nonequilibrium carriers is smaller than the charge on the external electrodes (Q K CU0, where C is the sample capacity and U0 is the applied voltage). If Q > CU0 , space-charge-limited current (SCLC) results. Standard SCLC theory, describing injection current peculiarities is presented in [1]. Also, the SCLC regime is achievable for optical carrier generation by powerful laser pulses (photoSCLC regime), and can be used, with some limitations [2], to study the density-of-states [3] and bimolecular recombination [4] in disordered materials. However, it must be mentioned that comprehensive interpretation of the photoSCLC regime has not been worked out so far. In this contribution we continue our previous studies [4,5] and present detailed theoretical analysis of the photoSCLC regime. The results of our analysis are compared with data, obtained from photoSCLC measurements in amorphous hydrogenized silicon a-Si:H.In analyzing the photoSCLC regime, we use the following assumptions of the standard SCLC theory: the one-dimensional description of the sandwich-like sample geometry, uniform initial distribution of the electric field, and negligible influence of thermal carrier generation. Carrier trapping, monomolecular recombination and diffusion are neglected. The carriers are generated by instantaneous light pulse. The bimolecular recombination as well as different resistivities of the detection resistor are taken into account. We solve the total current equation

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confidence: 83%

Peculiarities of Space-Charge-Limited Photocurrent

et al. 1997

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“…The recombination dynamics of photoexcited carriers in a-Si:H have been extensively investigated [9][10][11][12] by a variety of techniques of time-resolved laser spectroscopy. From a number of results of pump and probe measurements, a general picture emerged [10 -12]: The carrier recombination dynamics are insensitive to the pump intensities (monomolecular recombination) for injected carrier densities 5 10 17 cm − 3 per pump pulse, and they can be described well in terms of a multiple trapping model.…”

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confidence: 99%

Ultrafast carrier dynamics in undoped microcrystalline silicon

Kudrna

Malý

Trojánek

et al. 2000

Materials Science and Engineering: B

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We have studied ultrafast dynamics of photoexcited carriers in mc-Si:H by pump and probe laser spectroscopy. We have found that the dynamics of photoexcited carriers in mc-Si:H depend on the crystallinity of the material: in the samples with low crystalline fraction, the dynamics have a fast decay and resemble those in a-Si:H, while in the samples with high crystallinity the dynamics are slower and similar to those in c-Si. We have identified an intensity dependent bimolecular recombination in the samples with lower crystalline fraction (coefficient B = 2× 10 − 10 cm 3 s − 1 for deposition with silane dilution ratio :5% at a fixed power of 6 W), and no bimolecular recombination in the samples with high crystallinity.

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“…We investigate the transient optical response of the a-Si:H metasurface, by broadband polarization-resolved pump-probe spectroscopy. Importantly, the hydrogenated amorphous silicon (a-Si:H) offers much faster relaxation of free carriers in comparison to crystalline semiconductors, 31,32 hence the possibility for faster optical modulation. Our experimental setup is based on an amplified Ti:sapphire laser (Coherent, Libra) producing 100 fs pulses at 800 nm wavelength.…”

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confidence: 99%

“…33,34 In order to conserve the energy, each relaxation event occurs alongside phonon generation, which contributes to lattice heating with an energy equal to that of the electron-hole pair. 32 This causes an increase of the lattice temperature Θ with respect to the ambient temperature Θ a . The dynamical properties of the a-Si:H metasurface are thus governed by three variables, the pump pulse incident intensity I(t), the free-carrier density N (t), and the lattice temperature Θ(t).…”

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Nonlinear Anisotropic Dielectric Metasurfaces for Ultrafast Nanophotonics

et al. 2017

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We report on the broadband transient optical response of anisotropic, amorphous silicon nanobricks that exhibit Mie-type resonances. A quantitative model is developed to identify and disentangle the three physical processes that govern the ultrafast changes of the nanobrick optical properties, namely, two-photon absorption, free-carrier relaxation, and lattice heating. We reveal a set of operating windows where ultrafast all-optical modulation of transmission is achieved with full return to zero in 20 ps. This is made possible because of the distinct dispersive features exhibited by the competing nonlinear processes in transmission and despite the slow (nanosecond) internal lattice dynamics. The observed ultrafast switching behavior can be independently engineered for both orthogonal polarizations using the large anisotropy of nanobricks, thus allowing ultrafast anisotropy control. Our results categorically ascertain the potential of all-dielectric resonant nanophotonics as a platform for ultrafast optical devices and reveal the possibility for ultrafast polarization-multiplexed displays and polarization rotators

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The properties of free carriers in amorphous silicon

Cited by 80 publications

References 25 publications

Peculiarities of Space-Charge-Limited Photocurrent

Peculiarities of Space-Charge-Limited Photocurrent

Ultrafast carrier dynamics in undoped microcrystalline silicon

Nonlinear Anisotropic Dielectric Metasurfaces for Ultrafast Nanophotonics

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