Comparison of structure and properties of femtosecond and nanosecond laser-structured silicon

Crouch, Catherine H.; Carey, James E.; Warrender, Jeffrey M.; Aziz, Michael J.; Mazur, Eric; Génin, François Y.

doi:10.1063/1.1667004

Cited by 349 publications

(201 citation statements)

References 10 publications

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“…As a result, the mean electronic energy increases and, according to (1), the EEG increases. Thus, for very high electron densities 3 , the EEG will deviate, demonstrating the limits of the validity of (2).…”

Section: Dependence Of Eeg On Fluencementioning

confidence: 99%

Transient dynamics of the electronic subsystem of semiconductors irradiated with an ultrashort vacuum ultraviolet laser pulse

Medvedev¹,

Rethfeld²

2010

New J. Phys.

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Abstract. The irradiation of semiconductors with ultrashort laser pulses causes excitation of electrons from bound states (the valence band and deep atomic shells) to the conduction band, which produces non-equilibrium highly energetic free electrons. We apply a Monte-Carlo simulation technique to study the ionization and excitation of the electronic subsystem of a solid silicon target irradiated with a femtosecond laser pulse, obtaining the transient distribution of electrons within the conduction band. We take into account the electronic band structure and Pauli's principle for excited electrons. Secondary excitation and ionization processes induced by electrons in the conduction band and holes in the valence band were also included and simulated event by event. The temporal distributions of the density and the energy of excited electrons are calculated and discussed. We demonstrate that, due to the energy used to overcome the ionization potential, the final kinetic energy of the free electrons is significantly less than the total energy provided by the laser pulse. We extend the concept of an 'effective energy gap' for multiple electronic excitations, which can be applied to estimate the free-electron density after high-intensity vacuum ultraviolet (VUV) laser pulse irradiation. The effective energy gap depends on both the properties of the material and the laser pulse parameters. The concept provides a fundamental understanding of the experimentally accessible pair creation energy measured in the limit of long times.

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Section: Dependence Of Eeg On Fluencementioning

confidence: 99%

Transient dynamics of the electronic subsystem of semiconductors irradiated with an ultrashort vacuum ultraviolet laser pulse

Medvedev¹,

Rethfeld²

2010

New J. Phys.

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“…The IB permits photons with a low energy below the band gap of the semiconductor to be absorbed, yielding a high optical absorbance in the low energy part of the solar spectrum [2][3][4][5]. For deep impurities, like S and Se in Si with a binding energy of around 300 meV [6,7], the insulator-to-metal transition is a direct evidence for the formation of an IB in host semiconductors [8,9].…”

Section: Introductionmentioning

confidence: 99%

Realizing the insulator-to-metal transition in Se-hyperdoped Si via non-equilibrium material processing

Liu¹,

Prucnal²,

Berencén³

et al. 2017

J. Phys. D: Appl. Phys.

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“…5 Various methods exist for fabricating hyperdoped black silicon, in addition to methods for fabricating silicon that is hyperdoped but optically flat and methods for fabricating black silicon that is not hyperdoped. Hyperdoped black silicon can be fabricated by irradiating silicon with femtosecond 6 or nanosecond 7 laser pulses in the presence of dopants, which are typically in the form of a gas 6 or a thin film. 8 9 10 Laser irradiation parameters are used that both 1) hyperdope the silicon through a process of silicon melting, dopant diffusion into the melt, and solute trapping during rapid resolidification of the silicon, and 2) produce self-organized surface structures on the nanometer and micrometer scales that have light-trapping properties.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous high crystallinity and sub-bandgap optical absorptance in hyperdoped black silicon using nanosecond laser annealing

Franta

Pastor

Gandhi

et al. 2015

Journal of Applied Physics

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Hyperdoped black silicon fabricated with femtosecond laser irradiation has attracted interest for applications in infrared photodetectors and intermediate band photovoltaics due to its sub-bandgap optical absorptance and light-trapping surface. However, hyperdoped black silicon typically has an amorphous and polyphasic polycrystalline surface that can interfere with carrier transport, electrical rectification, and intermediate band formation. Past studies have used thermal annealing to obtain high crystallinity in hyperdoped black silicon, but thermal annealing causes a deactivation of the sub-bandgap optical absorptance. In this study, nanosecond laser annealing is used to obtain high crystallinity and remove pressure-induced phases in hyperdoped black silicon while maintaining high sub-bandgap optical absorptance and a light-trapping surface morphology. Furthermore, it is shown that nanosecond laser annealing reactivates the sub-bandgap optical absorptance of hyperdoped black silicon after deactivation by thermal annealing. Thermal annealing and nanosecond laser annealing can be combined in sequence to fabricate hyperdoped black silicon that simultaneously shows high crystallinity, high above-bandgap and sub-bandgap absorptance, and a rectifying electrical homojunction. Such nanosecond laser annealing could potentially be applied to non-equilibrium material systems beyond hyperdoped black silicon.

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Comparison of structure and properties of femtosecond and nanosecond laser-structured silicon

Abstract: . 2004. Comparison of structure and properties of femtosecond and nanosecond laser-structured silicon.

Cited by 349 publications

References 10 publications

Transient dynamics of the electronic subsystem of semiconductors irradiated with an ultrashort vacuum ultraviolet laser pulse

Transient dynamics of the electronic subsystem of semiconductors irradiated with an ultrashort vacuum ultraviolet laser pulse

Realizing the insulator-to-metal transition in Se-hyperdoped Si via non-equilibrium material processing

Simultaneous high crystallinity and sub-bandgap optical absorptance in hyperdoped black silicon using nanosecond laser annealing

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