Optical Waveguide Lightmode Spectroscopy (OWLS) as a Sensor for Thin Film and Quantum Dot Corrosion

Sensors

Hao Yu³  Carrick M. Eggleston²  Jiajun Chen¹  Wenyong Wang¹  Qilin Dai¹ 

[1]Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071, USA

[2] E-Mails:

[3]Department of Geology and Geophysics, University of Wyoming, Laramie, WY 82071, USA

[4]Department of Chemical and Petroleum Engineering, University of Wyoming, Laramie, WY 82071, USA

[5] E-Mail:

关键词: OWLS;    AFM;    waveguide sensors;    thin films;    quantum dots;    ZTO;    CdSe;   

DOI  :  10.3390/s121217330

来源: mdpi

【 摘 要 】

Optical waveguide lightmode spectroscopy (OWLS) is usually applied as a biosensor system to the sorption-desorption of proteins to waveguide surfaces. Here, we show that OWLS can be used to monitor the quality of oxide thin film materials and of coatings of pulsed laser deposition synthesized CdSe quantum dots (QDs) intended for solar energy applications. In addition to changes in data treatment and experimental procedure, oxide- or QD-coated waveguide sensors must be synthesized. We synthesized zinc stannate (Zn₂SnO₄) coated (Si,Ti)O₂ waveguide sensors, and used OWLS to monitor the relative mass of the film over time. Films lost mass over time, though at different rates due to variation in fluid flow and its physical effect on removal of film material. The Pulsed Laser Deposition (PLD) technique was used to deposit CdSe QD coatings on waveguides. Sensors exposed to pH 2 solution lost mass over time in an expected, roughly exponential manner. Sensors at pH 10, in contrast, were stable over time. Results were confirmed with atomic force microscopy imaging. Limiting factors in the use of OWLS in this manner include limitations on the annealing temperature that maybe used to synthesize the oxide film, and limitations on the thickness of the film to be studied. Nevertheless, the technique overcomes a number of difficulties in monitoring the quality of thin films in-situ in liquid environments.

【 授权许可】

CC BY   
© 2012 by the authors; licensee MDPI, Basel, Switzerland