Regeneration of titanium oxide nano-coated long-period grating biosensor

Dominik, Magdalena; Niedziółka‐Jönsson, Joanna; Roźniecka, Ewa; Wachnicki, Ł.; Godlewski, M.; Mikulic, Predrag; Bock, Wojtek J.; Śmietana, Mateusz

doi:10.1117/12.2236878

Cited by 2 publications

(3 citation statements)

References 10 publications

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“…Apart from the matter of measurements performed in alkali, also the process of biosensor regeneration that allows for its reusability, may require treatment in high-pH alkaline solutions. An example of this is a regeneration process of specific TiO 2 -overlaid optical fiber biosensors with silane-functionalized active surfaces, for which a solution with a pH 14 was applied [9,10]. Although such high pH value was not optimized and in further experiments it was confirmed that already the pH equal to 9 worked effectively for the sensor regeneration process [11], the alkali treatment still remains necessary.…”

Section: Introductionmentioning

confidence: 99%

“…For example Al 2 O 3 and SnO 2 are vulnerable to degradation in alkaline solutions because of their amphoteric chemical nature [24]. Probably for the same reason also TiO 2 layers are not totally safe during prolonged stay in alkali [9,10,25], and they may dissolve very slowly.…”

Section: Introductionmentioning

confidence: 99%

“…This is the reason why the ALD technique is a must in nowadays microelectronics [33,34], but at the same time it reaches more and more applications in other very divers branches [35,36]. It has also been used in optical sensors technology for a few years [9,10,[37][38][39][40]. It should be emphasized here that ALD allows for deposition at relatively low temperatures (LT), even much below 100 °C, that is an important advantage in comparison with the continuous-CVD method, especially when taking into account relatively low thermal stability of many optical sensor devices.…”

Section: Introductionmentioning

confidence: 99%

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Alkali-resistant low-temperature atomic-layer-deposited oxides for optical fiber sensor overlays

Kosiel¹,

Dominik²,

Ściślewska³

et al. 2018

Nanotechnology

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This paper presents an investigation of properties of selected metallic oxides deposited at a low temperature (100 °C) by atomic layer deposition (ALD) technique, relating to their applicability as thin overlays for optical fiber sensors resistant in alkaline environments. Hafnium oxide (Hf O with y/x approx. 2.70), tantalum oxide (Ta O with y/x approx. 2.75) and zirconium oxide (Zr O with y/x approx. 2.07), which deposition was based, respectively, on tetrakis(ethylmethyl)hafnium, tantalum pentachloride and tetrakis(ethylmethyl)zirconium with deionized water, were tested as thin layers on planar Si (100) and glass substrates. Growth per cycle (GPC) in the ALD processes was 0.133-0.150 nm/cycle. Run-to-run GPC reproducibility of the ALD processes was best for Hf O (0.145 ± 0.001 nm/cycle) and the poorest for Ta O (0.133 ± 0.003 nm/cycle). Refractive indices n of the layers were 2.00-2.10 (at the wavelength λ = 632 nm), with negligible k value (at λ for 240-930 nm). The oxides examined by x-ray diffractometry proved to be amorphous, with only small addition of crystalline phases for the Zr O . The surfaces of the oxides had grainy but smooth topographies with root-mean square roughness ∼0.5 nm (at 10 × 10 μm area) according to atomic force microscopy. Ellipsometric measurements, by contrast, suggest rougher surfaces for the Zr O layers. The surfaces were also slightly rougher on the glass-based samples than on the Si-based ones. Nanohardness and Young modules were 4.90-8.64 GPa and 83.7-104.4 GPa, respectively. The tests of scratch resistance revealed better tribological properties for the Hf O and the Ta O than for the Zr O . The surfaces were hydrophilic, with wetting angles of 52.5°-62.9°. The planar oxides on Si, being resistive even to concentrated alkali (pH 14), proved to be significantly more alkali-resistive than AlO. The Ta O overlay was deposited on long-period grating sensor induced in optical fiber. Thanks to such an overlay the sensor proved to be long-lasting resistant when exposed to alkaline environment with a pH 9. Thereby, it also proved that it has a potential to be repeatedly reused as a regenerable optical fiber biosensor.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Alkali-resistant low-temperature atomic-layer-deposited oxides for optical fiber sensor overlays

Kosiel¹,

Dominik²,

Ściślewska³

et al. 2018

Nanotechnology

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Compositional, structural, and optical properties of atomic layer deposited tantalum oxide for optical fiber sensor overlays

Kosiel

Pągowska

Kozubal

et al. 2018

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Although Ta2O5 is thermodynamically the most stable form of TaxOy, the chemical composition/stoichiometry of TaxOy films may generally be complex. On the other hand, to be robust in harsh chemical environments, the film material is required to be amorphous rather than crystalline. The amorphousness of atomic layer deposited (ALD) films is promoted by low process temperature generally. This paper presents the study on TaxOy films deposited by ALD at low temperature (100 °C) using TaCl5 and H2O as chemical precursors, bringing the compositional, structural, and optical properties of the films together. The films with the thickness in the range of 32–202.5 nm were deposited mostly on Si (100) wafers. For their characterization, secondary ion mass spectroscopy, Rutherford backscattering spectroscopy, x-ray photoelectron spectroscopy, x-ray diffractometry, and spectroscopic ellipsometry were performed. The films were overstoichiometric in relation to Ta2O5, with the O/Ta ratio in the range of 2.7–2.8. Additionally, some amount of surface O was bound within adsorbed -OH and -CO groups. The main contaminant of the films was Cl (5–5.5 at. %). The main contaminant of their surfaces and at the film/substrate interfaces was carbon (>50 at. %). All the films proved to be fully amorphous. Their real part of refractive index was very similar (n approximately 2) in the whole range of thicknesses, with differences of a few percent only. Optical attenuation was negligibly low.

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Regeneration of titanium oxide nano-coated long-period grating biosensor

Cited by 2 publications

References 10 publications

Alkali-resistant low-temperature atomic-layer-deposited oxides for optical fiber sensor overlays

Alkali-resistant low-temperature atomic-layer-deposited oxides for optical fiber sensor overlays

Compositional, structural, and optical properties of atomic layer deposited tantalum oxide for optical fiber sensor overlays

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