A study of optical absorption in amorphous hydrogenated silicon thin films of varied thickness

Müllerová, Jarmila; Prušáková, Lucie; Netrvalová, Marie; Vavruňková, Veronika; Šutta, P.

doi:10.1016/j.apsusc.2010.03.022

Cited by 40 publications

(22 citation statements)

References 20 publications

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“…Since thè polymers reside on thè surfaces of voids [2,[10][11][12], which are usually present in a-Si [2][3][4], thè increased density of thè polymers after annealing (Figs. 2 and 3) would thus suggest that thè size of thè nanovoids has increased to accommodate more polymers with respect to thè non-annealed state.…”

Section: Resultsmentioning

confidence: 99%

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From Nanovoids to Blisters in Hydrogenated Amorphous Silicon

Frigeri¹,

Nasi²,

Serényi

et al. 2013

Physics, Chemistry and Applications of Nanostructures

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Section: Resultsmentioning

confidence: 99%

“…Like in other amorphous materials, nanovoids are usually present in a-Si [2][3][4]. Since they are empty spaces they bring about density reduction, which can change thè refractive index, electronic defect states [1] and inhomogeneous stress distribution if filled with H [5] or if they forni Si-H platelets [6].…”

Section: Introductionmentioning

confidence: 99%

From Nanovoids to Blisters in Hydrogenated Amorphous Silicon

Frigeri¹,

Nasi²,

Serényi

et al. 2013

Physics, Chemistry and Applications of Nanostructures

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“…These structure features can be considered responsible for the sample inhomogeneities. Similarly according to our former knowledge [8], for the samples PECVD deposited at the substrate temperature of 250°C and the dilutions R = 0; 20, the presence of ordered domains of tetragonal silicon hydride was proved with the domain size of ∼ 10 nm. Correspondingly, no evidences of cubic diamond silicon crystallites were detected.…”

Section: Structure By Xrd Measurementsmentioning

confidence: 99%

“…The B factor includes information on the disorder-induced correlation of optical transition between the valence and conduction bands [15]. The decreasing B is the indicator of the phase transition from amorphous to the microcrystalline silicon [8]. The scale factor B depends on the product of the oscillator strength of the optical transition, the deformation potential and the mean deviation of the atomic coordinates; particularly the mean bond angle distribution in amorphous semiconductors [16].…”

Section: Optical Propertiesmentioning

confidence: 99%

“…There is still a discussion on the origin of the LSM and HSM absorption. Nevertheless it is widely agreed [8,20] that isolated hydrogen in the monohydride configuration in small volumes of vacancies contributes to the LSM. Clustered hydrogen in polyhydrides at the internal surfaces of voids or at the boundaries between the crystalline grains on the void surfaces contributes to the HSM.…”

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confidence: 99%

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Influence of deposition temperature on amorphous structure of PECVD deposited a-Si:H thin films

Müllerová¹,

Fischer²,

Netrvalová³

et al. 2011

Open Physics

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Abstract:The effect of deposition temperature on the structural and optical properties of amorphous hydrogenated silicon (a-Si:H) thin films deposited by plasma-enhanced chemical vapour deposition (PECVD) from silane diluted with hydrogen was under study. The series of thin films deposited at the deposition temperatures of 50 − 200°C were inspected by XRD, Raman spectroscopy and UV Vis spectrophotometry. All samples were found to be amorphous with no presence of the crystalline phase. Ordered silicon hydride regions were proved by XRD. Raman measurement analysis substantiated the results received from XRD showing that with increasing deposition temperature silicon-silicon bond-angle fluctuation decreases. The optical characterization based on transmittance spectra in the visible region presented that the refractive index exhibits upward trend with increasing deposition temperature, which can be caused by the densification of the amorphous network. We found out that the scale factor of the Tauc plot increases with the deposition temperature. This behaviour can be attributed to the increasing ordering of silicon hydride regions. The Tauc band gap energy, the iso-absorption value their difference were not particularly influenced by the deposition temperature. Improvements of the microstructure of the Si amorphous network have been deduced from the analysis.

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Revealing Structural Disorder in Hydrogenated Amorphous Silicon for a Low‐Loss Photonic Platform at Visible Frequencies

et al. 2021

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The high refractive index of hydrogenated amorphous silicon (a‐Si:H) at optical frequencies is an essential property for the efficient modulation of the phase and amplitude of light. However, substantial optical loss represented by its high extinction coefficient prevents it from being utilized widely. Here, the bonding configurations of a‐Si:H are investigated, in order to manipulate the extinction coefficient and produce a material that is competitive with conventional transparent materials, such as titanium dioxide and gallium nitride. This is achieved by controlling the hydrogenation and silicon disorder by adjusting the chemical deposition conditions. The extinction coefficient of the low‐loss a‐Si:H reaches a minimum of 0.082 at the wavelength of 450 nm, which is lower than that of crystalline silicon (0.13). Beam‐steering metasurfaces are demonstrated to validate the low‐loss optical properties, reaching measured efficiencies of 42%, 62%, and 75% at the wavelengths of 450, 532, and 635 nm, respectively. Considering its compatibility with mature complementary metal–oxide–semiconductor processes, the low‐loss a‐Si:H will provide a platform for efficient photonic operating in the full visible regime.

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A study of optical absorption in amorphous hydrogenated silicon thin films of varied thickness

Cited by 40 publications

References 20 publications

From Nanovoids to Blisters in Hydrogenated Amorphous Silicon

From Nanovoids to Blisters in Hydrogenated Amorphous Silicon

Influence of deposition temperature on amorphous structure of PECVD deposited a-Si:H thin films

Revealing Structural Disorder in Hydrogenated Amorphous Silicon for a Low‐Loss Photonic Platform at Visible Frequencies

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