Structural Anisotropy of Amorphous Silicon Films Modified by Femtosecond Laser Pulses

Shuleiko, D. V.; Kashaev, F. V.; Potemkin, F. V.; Zabotnov, S. V.; Zoteev, A. V.; Presnov, D. E.; Пархоменко, И. Н.; Romanov, I. A.

doi:10.1134/s0030400x18060218

Cited by 4 publications

(9 citation statements)

References 35 publications

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“…In addition, it should be noted that the periods of both normal and anomalous surface lattices formed by femtosecond laser pulses at the a-Si:H surface in the present work are smaller than those obtained by our group in the previous experiments using a lower laser fluence [ 12 , 21 ]. According to modeling within Sipe theory such decrease of the LIPSS period is attributed to a lower nonequilibrium electrons density achieved during laser processing.…”

Section: Resultscontrasting

confidence: 78%

“…The formation of a periodic relief on metal, dielectric, and semiconductor surfaces irradiated by femtosecond laser pulses is often associated with the surface electromagnetic waves (SEW) generation [ 21 ]. For the normal LIPSS formation, the conditions for a certain SEW mode excitation—a surface plasmon-polariton—must be satisfied at the interface between two media [ 13 ]:

where ε 1 = 1 is the dielectric permittivity corresponding to air, and ε 2 corresponds to the irradiated material.…”

Section: Theoretical Modeling Of the Lipss Formationmentioning

confidence: 99%

“…For the normal LIPSS formation, the conditions for a certain SEW mode excitation—a surface plasmon-polariton—must be satisfied at the interface between two media [ 13 ]:

where ε 1 = 1 is the dielectric permittivity corresponding to air, and ε 2 corresponds to the irradiated material. Therefore, in the case of semiconductors and dielectrics, including a-Si:H, it is necessary to achieve the negative sign of Re ε 2 for surface plasmon-polariton excitation [ 12 , 13 , 21 ]. The conditions (1) can arise in a-Si:H under irradiation with high-power femtosecond laser pulses.…”

Section: Theoretical Modeling Of the Lipss Formationmentioning

confidence: 99%

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Fabricating Femtosecond Laser-Induced Periodic Surface Structures with Electrophysical Anisotropy on Amorphous Silicon

et al. 2020

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One-dimensional periodic surface structures were formed by femtosecond laser irradiation of amorphous hydrogenated silicon (a-Si:H) films. The a-Si:H laser processing conditions influence on the periodic relief formation as well as correlation of irradiated surfaces structural properties with their electrophysical properties were investigated. The surface structures with the period of 0.88 and 1.12 μm were fabricated at the laser wavelength of 1.25 μm and laser pulse number of 30 and 750, respectively. The orientation of the surface structure is defined by the laser polarization and depends on the concentration of nonequilibrium carriers excited by the femtosecond laser pulses in the near-surface region of the film, which affects a mode of the excited surface electromagnetic wave which is responsible for the periodic relief formation. Femtosecond laser irradiation increases the a-Si:H films conductivity by 3 to 4 orders of magnitude, up to 1.2 × 10−5 S∙cm, due to formation of Si nanocrystalline phase with the volume fraction from 17 to 28%. Dark conductivity and photoconductivity anisotropy, observed in the irradiated a-Si:H films is explained by a depolarizing effect inside periodic microscale relief, nonuniform crystalline Si phase distribution, as well as different carrier mobility and lifetime in plane of the studied samples along and perpendicular to the laser-induced periodic surface structures orientation, that was confirmed by the measured photoconductivity and absorption coefficient spectra.

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Section: Resultscontrasting

confidence: 78%

where ε 1 = 1 is the dielectric permittivity corresponding to air, and ε 2 corresponds to the irradiated material.…”

Section: Theoretical Modeling Of the Lipss Formationmentioning

confidence: 99%

“…For the normal LIPSS formation, the conditions for a certain SEW mode excitation—a surface plasmon-polariton—must be satisfied at the interface between two media [ 13 ]:

Section: Theoretical Modeling Of the Lipss Formationmentioning

confidence: 99%

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Fabricating Femtosecond Laser-Induced Periodic Surface Structures with Electrophysical Anisotropy on Amorphous Silicon

et al. 2020

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“…Creation of the crystal layers of silicon from the amorphous by the heat treatement methods is an important process task [1][2][3]. In particular, the pulse laser annealing technologies for the amorphous silicon can be applied to create crystal layers of silicon [1] and complex heterostructures with crystal inclusions of silicon with the crystal inclusions of silicon with sizes of several nanometers [2]. After the ion implantation, the thermal annealing of the defects and the amorphization of the crystal layer is a standard procedure of the microelectronics technology [4].…”

Section: Introductionmentioning

confidence: 99%

“…The application of the light Raman scattering spectroscopy (RS) allows determining conditions of occurrence of the crystalline phase on the amorphous layer, the sizes of separate crystallites, the volume portion of the newly-formed phase [1,2] and the portions of the oriented crystallites [3]. The study of the angular dependences of the intensity of the RS polarized components in these layers shows a significant portion of the ordered crystallites [1,3].…”

Section: Introductionmentioning

confidence: 99%

The degree of polarization of Raman scattering of light in silicon nanocrystals

A.V.

2022

Semiconductors

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Raman scattering of light (RS) on an array of oriented silicon nanocrystals was studied experimentally. The angular dependence of the intensity of the polarized components of the RS was measured and the parameter of the degree of polarization of scattered light was determined. It was found that the degree of polarization of the RS is related to the size of the nanocrystals in the samples. An array of nanocrystals with the same crystallographic orientation was obtained by thermal annealing of a silicon single crystal damaged by ion implantation. During thermal annealing of the sample, the crystallinity of the layer is restored not simultaneously in the entire damaged volume, but in the form of nanocrystals separated by amorphous area. All the clusters formed have the same crystallographic orientation of the original single crystal. The features of the degree of polarization of the RS in nanocrystals are associated with the quantum-mechanical uncertainty of the phonon wave vector and the uncertainty of the phonon direction in a limited volume of the nanocrystal. The relations linking the degree of polarization of the RS with the size of nanocrystals are obtained. A technique for determining the size of nanocrystals by measuring the degree of polarization of the RS is discussed. Keywords: Raman scattering of light, silicon, nanocrystals, ion implantation, annealing, amorphous phase.

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Evolution of femtosecond laser-induced periodic structures formed on amorphous silicon surface

Shuleiko

Martyshov

Presnov

et al. 2020

J. Phys.: Conf. Ser.

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The laser-induced periodic surface structures (LIPSS) with period close to the femtosecond laser radiation wavelength (1.25 μm) were formed on amorphous hydrogenated silicon films (a-Si:H). The ripple ridges direction relative to laser radiation polarization was changed from perpendicular to parallel with increasing number of pulses from 50 to 1000. The experimentally observed LIPSS evolution is in a good agreement with the model proposed by J.E. Sipe where so-called efficacy factor depends on the real and imaginary parts of the dielectric constant and defines the LIPSS wave vector on the irradiated surface. In turn, the dielectric constant complex value is varied due to concentration change for the nonequilibrium electrons excited by different number of high-power femtosecond laser pulses. According to the theoretical modelling, the excited nonequilibrium electron concentration required for turning the LIPSS direction is equal to 8.2·1021 cm−3.

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Structural Anisotropy of Amorphous Silicon Films Modified by Femtosecond Laser Pulses

Cited by 4 publications

References 35 publications

Fabricating Femtosecond Laser-Induced Periodic Surface Structures with Electrophysical Anisotropy on Amorphous Silicon

Fabricating Femtosecond Laser-Induced Periodic Surface Structures with Electrophysical Anisotropy on Amorphous Silicon

The degree of polarization of Raman scattering of light in silicon nanocrystals

Evolution of femtosecond laser-induced periodic structures formed on amorphous silicon surface

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