Alkali-resistant low-temperature atomic-layer-deposited oxides for optical fiber sensor overlays
PBN-AR
Instytucja
Instytut Transportu Samochodowego
Informacje podstawowe
Główny język publikacji
en
Czasopismo
Nanotechnology (35pkt w roku publikacji)
ISSN
0957-4484
EISSN
1361-6528
Wydawca
IOP PUBLISHING LTD
DOI
URL
Rok publikacji
2018
Numer zeszytu
13
Strony od-do
135602-135602
Numer tomu
29
Identyfikator DOI
Liczba arkuszy
Słowa kluczowe
en
optical fiber sensors; thin film overlays; atomic layer deposition; alkali-resistant materials; long-period gratings
Streszczenia
Język
en
Treść
This paper presents an investigation of properties of selected metallic oxides deposited at a low temperature (100 degrees C) by atomic layer deposition (ALD) technique, relating to their applicability as thin overlays for optical fiber sensors resistant in alkaline environments. Hafnium oxide (HfxOy with y/x approx. 2.70), tantalum oxide (TaxOy with y/x approx. 2.75) and zirconium oxide (ZrxOy 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 HfxOy (0.145 +/- 0.001 nm/cycle) and the poorest for TaxOy (0.133 +/- 0.003 nm/cycle). Refractive indices n of the layers were 2.00-2.10 (at the wavelength lambda = 632 nm), with negligible k value (at lambda for 240-930 nm). The oxides examined by x-ray diffractometry proved to be amorphous, with only small addition of crystalline phases for the ZrxOy. The surfaces of the oxides had grainy but smooth topographies with root-mean square roughness similar to 0.5 nm (at 10 x 10 mu m(2) area) according to atomic force microscopy. Ellipsometric measurements, by contrast, suggest rougher surfaces for the ZrxOy 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 HfxOy and the TaxOy than for the ZrxOy. The surfaces were hydrophilic, with wetting angles of 52.5 degrees-62.9 degrees. The planar oxides on Si, being resistive even to concentrated alkali (pH 14), proved to be significantly more alkali-resistive than Al2O3. The TaxOy 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.
Cechy publikacji
ORIGINAL_ARTICLE
Inne
System-identifier
858394
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