Internal friction of amorphous and nanocrystalline silicon at low temperatures

Liu, Xiao; Spiel, C.L; Merithew, R. D.; Pohl, Robert Wichard; Nelson, B. P.; Wang, Qi; Crandall, Richard S.

doi:10.1016/j.msea.2006.01.146

Cited by 13 publications

(11 citation statements)

References 23 publications

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“…Recent work by Liu et al [42] reported that further improvements to the loss of e-beam films can be made at low temperatures by depositing the coatings with an elevated substrate temperature. Furthermore, a-Si films grown using hot-wire chemical vapour deposition (HWCVD) to produce hydrogenated a-Si-H were observed to have losses as low as ∼ 4 × 10 −7 at 10 K [40,41,43,44]. This is over three orders of magnitude lower than observed on tantala films at a similar temperature.…”

Section: Introductionmentioning

confidence: 91%

“…Liu et al [40,41,43,44] conducted investigations on the ∼ 5.5 kHz anti-symmetric mode of a double paddle silicon oscillator created using several different deposition techniques. As summarised in table I, the losses of both magnetron sputtered and e-beam a-Si films are higher at 10 K and 100 K, but similar improvement in the losses were observed after heat treatment.…”

Section: B Comparison With Other Deposited Amorphous Silicon Filmsmentioning

confidence: 99%

“…They also have a level of loss similar to a series of low-pressure hot-wire chemical vapor deposited (HWCVD) and plasma-enhanced chemical-vapour deposition (PECVD) amorphous silicon films grown in H 2 diluted silane (a-Si H 2 :SiH 4 ) at differing deposition and flow rates in order to vary the hydrogen content. HWCVD hydrogenated amorphous silicon [44] 0.005 − 0.9 0.035 − 5 -HWCVD a-Si H2:SiH4 [44] 0.25 − 0.4 0.8 − 1.5 -PECVD [44] 0.035 − 0.4 0.045 − 8 -(a-Si H) films grown at differing deposition rates to vary the hydrogen content show a large range in the loss, with a-Si H films produced with one atomic percentage of hydrogen (1 at.% H) observed to have levels of loss more than two orders of magnitude smaller than coatings produced by all other deposition techniques.…”

Section: B Comparison With Other Deposited Amorphous Silicon Filmsmentioning

confidence: 99%

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Ion-beam sputtered amorphous silicon films for cryogenic precision measurement systems

et al. 2015

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Thermal noise resulting from the mechanical loss of multi-layer dielectric coatings is expected to impose a limit to the sensitivities of precision measurement systems used in fundamental and applied science. In the case of gravitational wave astronomy, future interferometric gravitational wave detectors are likely to operate at cryogenic temperatures to reduce such thermal noise and ameliorate thermal loading effects, with the desirable thermo-mechanical properties of silicon making it an attractive mirror substrate choice for this purpose. For use in such a configuration of precision instrument, appropriate coatings of low thermal noise are essential. Amorphous silicon (a-Si) deposited by e-beam and other techniques has been shown to have low mechanical loss. However, to date, the levels of mechanical and optical loss for a-Si when deposited by ion-beam-sputtering (the technique required to produce amorphous mirrors of the specification for gravitational wave detector mirrors) are unknown. In this paper results from measurements of the mechanical loss of a series of IBS a-Si films are presented which show that reductions are possible in coating thermal noise of a factor of 1.5 at 120 K and 2.1 at 20 K over the current best IBS coatings (alternating stacks of silica and titania-doped tantala), with further reductions feasible under appropriate heat treatments.

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Section: Introductionmentioning

confidence: 91%

Section: B Comparison With Other Deposited Amorphous Silicon Filmsmentioning

confidence: 99%

Section: B Comparison With Other Deposited Amorphous Silicon Filmsmentioning

confidence: 99%

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Ion-beam sputtered amorphous silicon films for cryogenic precision measurement systems

et al. 2015

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“…Thus to minimize coating thermal noise a material of high refractive index and low mechanical loss is desirable. In comparison to tantala, amorphous silicon (aSi) shows low mechanical loss at low temperatures [15] and has a high index of refraction which would both result in a significant thermal noise reduction, if aSi was used for the high-index layers of a mirror coating.…”

Section: Introductionmentioning

confidence: 99%

Optical absorption of ion-beam sputtered amorphous silicon coatings

et al. 2016

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Low mechanical loss at low temperatures and a high index of refraction should make silicon optimally suited for thermal noise reduction in highly-reflective mirror coatings for gravitational wave detectors. However, due to high optical absorption, amorphous silicon (aSi) is unsuitable for being used as a direct high-index coating material to replace tantala. A possible solution is a multimaterial design, which enables exploitation of the excellent mechanical properties of aSi in the lower coating layers. The possible number of aSi layers increases with absorption reduction. In this work, the optimum heat treatment temperature of aSi deposited via ion-beam sputtering was investigated and found to be 450 • C. For this temperature, the absorption after deposition of a single layer of aSi at 1064 nm and 1550 nm was reduced by more than 80 %.

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“…A promising coating material with low mechanical loss is amorphous silicon (aSi) [6,7], but the optical absorption at the planned laser wavelength of 1550 nm is far too high (1000 ppm for a HR coating [8]), while it is only 1.7 ppm [9] for a SiO 2 and Ta 2 O 5 coating. Research on absorption reduction in aSi is ongoing [10].…”

Section: Introductionmentioning

confidence: 99%

High index top layer for multimaterial coatings

Steinlechner

Martin

2016

Phys. Rev. D

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For application in future cryogenically cooled gravitational wave detectors, the thermal noise of low absorbing mirror coatings has to be reduced. The development of low mechanical and optical loss materials is challenging, but thermal noise reduction can be significantly supported by using a multi-material coating design. We analyze the possible improvement of the total (optical and mechanical) loss of a three-material based coating obtained by optimizing the properties of the top layer of the coating stack. A top-layer material with sufficiently high refractive index could have significantly higher optical and mechanical loss than currently used tantala, while still enabling reduction of the total coating loss. Restrictions on possible top-layer material properties are made, and the option of a crystalline top layer is discussed.

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Internal friction of amorphous and nanocrystalline silicon at low temperatures

Cited by 13 publications

References 23 publications

Ion-beam sputtered amorphous silicon films for cryogenic precision measurement systems

Ion-beam sputtered amorphous silicon films for cryogenic precision measurement systems

Optical absorption of ion-beam sputtered amorphous silicon coatings

High index top layer for multimaterial coatings

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