Effect of annealing in a various oxygen atmosphere on structural, optical, electrical and gas sensing properties of MoxOy thin films

• DOI: 10.1016/j.optmat.2015.03.017
• Publication Date: 2015-04-06T04:16:29Z
• Authors: A. Arfaoui; B. Ouni; S. Touihri; A. Mhamdi; A. Labidi; T. Manoubi
• Keywords: 02 engineering and technology; 0210 nano-technology

Abstract Molybdenum oxide thin films were thermally evaporated on a glass substrate and monitored by an annealing process in a variable oxygen atmosphere. The effects of post annealing condition on the microstructural, morphological, optical and electrical properties were investigated using X-ray diffraction, Raman spectroscopy, atomic force microscope, spectroscopic ellipsometry and impedance spectroscopy. As-deposited amorphous films crystallized into tetragonal metastable phase of Mo 5 O 14 on annealing at 500 °C in vacuum and air. This structure transformed to stable orthorhombic of MoO 3 with annealing in oxygen environment. The optical parameters such as the refractive index, extinction coefficient, optical band gap energy and the Urbach energy were calculated from Cauchy formalism. Ellipsometric measurements reveal that the samples present optical gap located between 3.24 and 3.90 eV when the atmosphere becomes rich on oxygen. The variation of the conductivity in terms of the temperature shows an electrical behavior with oxygen environment. Finally, it has been found that MoO 3 thin films had high sensitivity to ethanol, which made them as a good candidate for the ethanol sensor.