Spectroscopic ellipsometry and ultraviolet-visible (UV-VIS) spectrometry were utilized to study the optical properties of ferroelectric lead lanthanum zirconate titanate (PLZT) films. These films were deposited on platinized silicon [Si(100)/ SiO2/TiO2/Pt(111)] substrates using the chemical solution deposition method. Films were annealed at two different temperatures (650 and 750 °C) using rapid thermal annealing. Shimadzu UV-1800 UV-VIS spectrophotometer with a resolution of 1 nm was used to measure the reflectance data in the spectral range of 300–1000 nm with a step size of 1 nm. The bandgap values were determined from the reflectance spectra using appropriate equations. A J.A. Woollam RC2 small spot spectroscopic ellipsometer was used to obtain the change in amplitude (Ψ) and phase (Δ) of polarized light upon reflection from the film surface. The spectra were recorded in the wavelength range of 210–1500 nm at an incident angle of 65°. Refractive index (n) and extinction coefficient (k) were obtained by fitting the spectra (Ψ, Δ) with the appropriate models. No significant changes were observed in the optical constants of PLZT films annealed at 650 and 750 °C. The optical transparency and the strong absorption in the ultraviolet (UV) region of PLZT films make them an attractive material for optoelectronic and UV sensing applications.
Nanostructured noble metals such as gold exhibit unique size‐dependent plasmonic and optical properties which is an enabling factor for designing nanophotonic devices. However, for its deployment in high temperature applications such as solar thermal energy harvesting and optothermal conversion, it requires understanding of its temperature dependent optical properties. This paper investigates the in situ specular reflectance of nanoporous gold (NPG) thin films in the wavelength range between 400 and 1000 nm at temperatures ranging from 25 to 500 °C via a home‐built fiber‐based optical spectrometer. During heating, the NPG's ligaments coalesce from an initial size of 39 ± 12 nm to a final size of up to 299 ± 114 nm, and its ligament scales with temperature closely matching an Arrhenius dependence. The surface roughness of NPG is empirically correlated to ligament size and temperature to allow for the theoretical prediction of the relative specular reflectance using scattering coefficients and effective medium theory which closely matches the experimental results. These results represent a step forward in using in situ optical spectroscopic methods to monitor the ligament size evolution of NPG thin‐films and to understand its stability and optical properties for applications at elevated temperatures.
more » « less- NSF-PAR ID:
- 10367447
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Optical Materials
- Volume:
- 10
- Issue:
- 10
- ISSN:
- 2195-1071
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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