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Ellipsometric characterization of tungsten oxide thin films, before and after He plasma exposure

M. I. RUSU1,* , Y. ADDAB2, C. MARTIN2, C. PARDANAUD2, V. SAVU1,* , I. I. LANCRANJAN1, D. TENCIU1

Affiliation

  1. National Institute of R&D for Optoelectronics INOE 2000, 409 Atomistilor, Magurele, PO Box MG-5, 77125, Ilfov, Romania
  2. Aix-Marseille Université, CNRS, PIIM UMR 7345, 13397, Marseille, France

Abstract

Thin films of WO3 were grown by thermal oxidation on tungsten substrates at 400 °C, under 590 Torr oxygen pressure. Two of the WO3 films were exposed to helium plasma, one at room temperature, and the other one at 400 °C. In order to determine and confirm the tungsten oxides thicknesses between 25 and 75 nm as previously estimated from Scanning Electron Microscopy (the cross-section of samples was prepared by Focused Ion Beam), ellipsometry measurements and modelling were performed. The specular reflectance spectra of the WO3 thin films were acquired in the range 190-2100 nm, showing that the reflectivity of the films decreases with WO3 layer thickness, especially at low wavelengths. It was observed that He exposed samples present lower values of refractive index and extinction coefficient compared to the unexposed sample.

Keywords

Tungsten oxide, Thermal oxidation, Thin films, Ellipsometry characterization, Reflectance.

Citation

M. I. RUSU, Y. ADDAB, C. MARTIN, C. PARDANAUD, V. SAVU, I. I. LANCRANJAN, D. TENCIU, Ellipsometric characterization of tungsten oxide thin films, before and after He plasma exposure, Optoelectronics and Advanced Materials - Rapid Communications, 17, 3-4, March-April 2023, pp.159-164 (2023).

Submitted at: Feb. 24, 2023

Accepted at: April 7, 2023