Optical waveguide lightmode spectroscopy (OWLS) as a sensor for thin film and quantum dot corrosion

Area of Science:

• Materials Science
• Nanotechnology
• Spectroscopy

Background:

• Optical waveguide lightmode spectroscopy (OWLS) is typically used for biosensing protein interactions.
• Monitoring thin film quality in situ, particularly in liquid environments, presents significant challenges.

Purpose of the Study:

• To demonstrate the application of OWLS for evaluating oxide thin films and cadmium selenide (CdSe) quantum dot (QD) coatings.
• To assess the stability and mass changes of synthesized thin films and QD coatings under varying conditions.

Main Methods:

• Synthesis of zinc stannate (Zn(2)SnO(4)) coated (Si,Ti)O(2) waveguide sensors.
• Deposition of CdSe QDs on waveguides using Pulsed Laser Deposition (PLD).
• In situ monitoring of film mass changes using OWLS in liquid environments (pH 2 and pH 10).
• Confirmation of results using atomic force microscopy (AFM).

Main Results:

• Zn(2)SnO(4) coated waveguides showed mass loss over time, influenced by fluid flow.
• CdSe QD coated waveguides exhibited mass loss at pH 2, while remaining stable at pH 10.
• OWLS effectively monitored real-time mass variations in the thin films.

Conclusions:

• OWLS is a viable technique for in situ monitoring of oxide and QD thin film quality for solar energy applications.
• The method provides insights into film stability and degradation mechanisms in liquid media.
• Limitations include annealing temperature and film thickness constraints, but the technique offers advantages over traditional methods.