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Title: Effect of Film Morphology and Thickness on Charge Transport in Ta 3 N 5 /Ta Photoanodes for Solar Water Splitting
Award ID(s):
0802907
NSF-PAR ID:
10041138
Author(s) / Creator(s):
; ;
Date Published:
Journal Name:
The Journal of Physical Chemistry C
Volume:
116
Issue:
30
ISSN:
1932-7447
Page Range / eLocation ID:
15918 to 15924
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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  3. Optical coatings formed from amorphous oxide thin films have many applications in precision measurements. The Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) and Advanced Virgo use coatings ofSiO2(silica) andTiO2:Ta2O5(titania-doped tantala) and post-deposition annealing to 500°C to achieve low thermal noise and low optical absorption. Optical scattering by these coatings is a key limit to the sensitivity of the detectors. This paper describes optical scattering measurements for single-layer, ion-beam-sputtered thin films on fused silica substrates: two samples ofTa2O5and two ofTiO2:Ta2O5. Using an imaging scatterometer at a fixed scattering angle of 12.8°, in-situ changes in the optical scatter of each sample were assessed during post-deposition annealing to 500°C in vacuum. The scatter of three of the four coated optics was observed to decrease during the annealing process, by 25–30% for tantala and up to 74% for titania-doped tantala, while the scatter from the fourth sample held constant. Angle-resolved scatter measurements performed before and after vacuum annealing suggest some improvement in three of the four samples. These results demonstrate that post-deposition, high-temperature annealing of single-layer tantala and titania-doped tantala thin films in vacuum does not lead to an increase in scatter, and may actually improve their scatter.

     
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